Focal knee arthroplasty is an attractive alternative to knee arthroplasty for young patients because it allows preservation of a large amount of bone for potential revisions. However, the mechanical behaviour of cartilage has not yet been investigated because it is challenging to evaluate in vivo contact areas, pressure, and deformations from metal implants. Therefore, this study aimed to determine the contact pressure in the tibiofemoral joint with a focal knee arthroplasty using a finite element model. The mechanical behaviour of the cartilage surrounding a metal implant was evaluated using finite element analysis. We modelled focal knee arthroplasty with placement flush, 0.5 mm deep, or protruding 0.5 mm with regard to the level of the surrounding cartilage. We compared contact stress and pressure for bone, implant, and cartilage under static loading conditions.Aims
Methods
Surgical debridement for medial epicondylitis (ME) is indicated for patients with refractory ME. The clinical efficacy of simple debridement has not been studied sufficiently. Moreover, authors experienced surgical outcome of ME was not as good as lateral epicondylitis. In this regard, authors have combined the atelocollagen injection in the debridement surgery of ME. The purpose of study was to compare clinical outcomes between simple debridement and debridement combined with atelocollagen injection in the ME. Twenty-five patients with refractory ME and underwent surgical debridement were included in the study. Group A (n=13) was treated with isolated debridement surgery, and group B (n=12) was treated with debridement combined with 1.0 mL of type I atelocollagen. Pain and functional improvements were assessed using visual analogue scale, Mayo Elbow Performance Score (MEPS) and quick Disabilities of the Arm, Shoulder and Hand (DASH) scale respectively before surgery, at 3, 6 months after surgery and at the final follow-up. Demographic data did not show significant difference between two groups before surgical procedures. Both groups showed improvement in pain and functional score postoperatively. However, at the 3 months after surgery, group B showed significantly better improvement as compared to group A(VAS 3.1 / 2.0, MEPS 71/82 qDASH 29/23). At the 6 months after surgery and final follow-up, both groups did not show any difference. Surgical debridement combined with atelocollagen is effective treatment option in refractory ME and showed better short-term outcomes compared to isolated surgery.
Olecranon plates used for the internal fixation of complex olecranon fractures are applied directly over the triceps tendon on the posterior aspect of the olecranon. The aim of the study is to describe the relationship of the plates and screws to the triceps tendon at the level of the olecranon. Eight cadaveric elbows were used. Dimensions of the triceps tendon at the insertion and 1cm proximal were measured. A long or a short olecranon plate was then applied over the olecranon and the most proximal screw applied. The length of the plate impinging on the tendon and the level of the screw tract on the tendon and bone were measured. The mean olecranon height was 24.3cm (22.4-26.9cm) with a tip-to-tendon distance of 14.5cm (11.9-16.2cm). The triceps tendon footprint averaged 13.3cm (11.7-14.9cm) and 8.8cm (7.6-10.2cm) in width and length, respectively. The mean width of the central tendon 1 cm proximal to the footprint was 6.8 cm. The long olecranon plate overlay over more movable tendon length than did the short plate and consequently the superior screw pierced the triceps tendon more proximally with the long plate. Using the Mann-Whitney U test, the differences were significant. The long olecranon plates encroach on more triceps tendon than short plates. This may be an important consideration for olecranon fractures with regards implant loosening or triceps tendon injury.
To test the hypothesis that reseeded anterior cruciate ligament (ACL)-derived cells have a better ability to survive and integrate into tendon extracellular matrix (ECM) and accelerate the ligamentization process, compared to adipose-derived mesenchymal stem cells (ADMSCs). Acellularized tibialis allograft tendons were used. Tendons were randomly reseeded with ACL-derived cells or ADMSCs. ACL-derived cells were harvested and isolated from remnants of ruptured ACLs during reconstruction surgery and cultured at passage three. Cell suspensions (200 µl) containing 2 × 106 ACL-derived cells or ADMSCs were prepared for the purpose of reseeding. At days 1, 3, and 7 post-reseeding, graft composites were assessed for repopulation with histological and immunohistochemical analysis. Matrix protein contents and gene expression levels were analyzed.Aims
Methods
The aim of this study was to assess and compare active rotation of the forearm in normal subjects after the application of a short-arm cast (SAC) in the semisupination position and a long-arm cast (LAC) in the neutral position. A clinical study was also conducted to compare the functional outcomes of using a SAC in the semisupination position with those of using a LAC in the neutral position in patients who underwent arthroscopic triangular fibrocartilage complex (TFCC) foveal repair. A total of 40 healthy right-handed volunteers were recruited. Active pronation and supination of the forearm were measured in each subject using a goniometer. In the retrospective clinical study, 40 patients who underwent arthroscopic foveal repair were included. The wrist was immobilized postoperatively using a SAC in the semisupination position (approximately 45°) in 16 patients and a LAC in 24. Clinical outcomes were assessed using grip strength and patient-reported outcomes. The degree of disability caused by cast immobilization was also evaluated when the cast was removed.Aims
Methods
There are concerns regarding initial stability and early periprosthetic fractures in cementless hip arthroplasty using short stems. This study aimed to investigate stress on the cortical bone around the stem and micromotions between the stem and cortical bone according to femoral stem length and positioning. In total, 12 femoral finite element models (FEMs) were constructed and tested in walking and stair-climbing. Femoral stems of three different lengths and two different positions were simulated, assuming press-fit fixation within each FEM. Stress on the cortical bone and micromotions between the stem and bone were measured in each condition.Aims
Methods
No randomized comparative study has compared the extensile lateral approach (ELA) and sinus tarsi approach (STA) for Sanders type 2 calcaneal fractures. This randomized comparative study was conducted to confirm whether the STA was prone to fewer wound complications than the ELA. Between August 2013 and August 2018, 64 patients with Sanders type 2 calcaneus fractures were randomly assigned to receive surgical treatment by the ELA (32 patients) and STA (32 patients). The primary outcome was development of wound complications. The secondary outcomes were postoperative complications, pain scored of a visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, 36-item Short Form health survey, operative duration, subtalar joint range of motion (ROM), Böhler’s angle and calcaneal width, and posterior facet reduction.Aims
Methods
This study aimed to evaluate the incidence and prognosis of patients with spinal metastasis as the initial manifestation of malignancy (SM-IMM). We retrospectively reviewed the electronic medical records of 338 patients who underwent surgical treatment for metastatic spinal disease. The enrolled patients were divided into two groups. The SM-IMM group included patients with no history of malignancy whose site of primary malignancy was diagnosed after the identification of spinal metastasis. The other group included patients with a history of treatment for primary malignancy who then developed spinal metastasis (SM-DTM). The incidence of SM-IMM by site of primary malignancy was calculated. The difference between prognoses after surgical treatment for SM-IMM and SM-DTM was established.Aims
Patients and Methods
Joint arthroplasties may be associated with a blood loss, which necessitates transfusion. Especially, hip arthroplasties are highly associate with transfusion to compensate perioperative bleeding. Orthopaedic surgeons and patients have increasing concerns regarding complications of blood transfusions. Although various methods to reduce transfusions have been attempted in TJA, a high percentage of patients require a transfusion during and after the procedures. The purposes of this study were to evaluate the trends of the transfusion(transfusion rates, transfusion amounts, economic burden) in hip arthroplasties, using nationwide data from the National Health Insurance Service (NHIS). We used data from nationwide claims database of Health Insurance Review Assessment Service (HIRA). The data managed by the NHIS were used to identify the 161,934 hip arthroplasties by 3 categories including bipolar hemiarthroplasty(BH), total hip arthroplasty(THA), and revision arthroplasty(RA) from 2007 to 2015. These 3 categories were classified using the operation code recorded in the requisition data of NHIS. The transfusion rates, transfusion amounts, proportion of transfusion, cost of each type of operation was investigated and stratified by age, gender, hospital type, and area in hip arthroplasties. The proportion of transfusion about whole blood, red blood cell, fresh frozen plasma, platelet, was also evaluated in hip arthroplasties.Aims
Patients and methods
Previous hemodynamics studies in shoulder arthroplasty only evaluated Western population and mainly focused on risk factors of transfusion. However, Asians are relatively small, and have higher bleeding risk due to prothrombin-clotting-factor polymorphisms. Therefore, it is not appropriate to apply the results of previously studies directly to Asians. Authors compare different hemodynamics depending on the types of shoulder arthroplasties, and evaluate predictors for transfusion in Asian population. Total 212 shoulder arthroplasties (26 fracture hemiarthroplasty (fHA), 49 anatomical total shoulder arthroplasty (aTSA), 132 reverse total shoulder arthroplasty (rTSA), and 5 revision surgery) from August 2004 to January 2016 were retrospectively reviewed. Demographics, surgical factors and perioperative hemodynamic factors were compared for each type of arthroplasty. Multivariate regression analysis was conducted to determine predictors for transfusion.Introduction
Methods
A stem sitting proud (SP) or that above the final rasp position remains in some patients who undergo hip replacement using proximally coated tapered wedge stems. Surgeons may face challenges providing the best fit due to unpredictable stem seating. Zimmer Inc. introduced a new rasp to solve this issue but the clinical results of this rasp have not yet been published. Therefore, we aimed to address the following: 1) What is SP incidence using a proximally coated cementless tapered wedge stem? 2) Does the new rasp system improve seating height? 3) What are the risk factors of SP? We performed a retrospective study with 338 hips, in which Tri-Lock Bone Preservation Stem (BPS) was used in 181 and M/L Taper stem was used in 157 hips (82 hips before and 75 hips after the new rasp). A positive stem SP was defined as a stem proud height of >2 mm. We analyzed and compared SP incidence in two stems and in M/L Taper stems before and after the new rasp use.Background
Methods
Clinical outcome after reverse total shoulder arthroplasty (RTSA) can be influenced by technical and implant-related factors, so the purpose of this study was to investigate whether individualizing humeral retroversion and subscapularis repair affect the clinical outcomes after RTSA. Authors retrospectively analyzed the prospectively collected data from 80 patients who underwent RTSA from January 2007 to January 2015 using same implant (Biomet Comprehensive® Reverse Shoulder System, Warsaw, Indiana). The mean follow up was 23.3 ± 1.7 (range, 12 ∼ 70) months. The retroversion of humeral component was decided according to native version estimated using shoulder CT in Group I (n=52), and fixed in 20° retroversion in Group II (n=28). Group I was subdivided into Group Ia (n=21, mean 19.3°), less than 20° of retroversion, and Group Ib (n=31, mean 31.9°), more than 20°. Intraoperative tenotomized subscapularis was repaired in 40 patients in Group I, and could not be repaired due to massive tear including subscapularis in remaining 12 patients. Clinical outcomes were evaluated with range of motion (ROM) and several clinical outcome scores.Introduction & Background
Material & Method
Acetabular dysplasia cause hip joint osteoarthritis(OA) by change hip mechanism. However, to our best knowledge, no studies have been published using prospectively collected data from asymptomatic young age volunteers, precise radiographic method. The purpose of this study is to evaluate the prevalence of hip dysplasia in asymptomatic Korean population as one of the most important risk factor of hip OA. From December 2014 to March 2015, we investigated prospectively collected retrospectively reviewed data of 200 asymptomatic volunteers 400 hips in age between 18 and 50 years recruited from our institution. Pelvic radiographs were taken and all radiographs were reviewed by 2 experienced orthopedic surgeons. Lateral center-edge angle(LCEA), Sharp angle, Tonnis angle and acetabular width-depth ratio were measured. We analyzed the statistical differences of these values between sex by Mann-Whitney U test and independent t-test. Pearson's correlation coefficient was used to measure the relationship between dysplasia parameters.Introduction
Materials & Methods
We report a case of fatal heart failure caused by cobalt intoxication after revision THR in the patient who successfully underwent re-revision THR. 53-year old male presented to emergency room in our hospital with progressive shortness of breath. Symptom was started about 6 months ago so he visited local hospital. He worked up for worsening dyspnea. Simple chest radiograph and enhanced heart MRI study were performed and they showed bilateral pericardial and pleural effusion. There was no evidence of ischemic change. Transthoracic echocardiogram showed the evidence of heart failure, left ventricular ejection fraction(EF) was 40%. He was admitted at local hospital and started on vasopressors but urine output was decreased and follow-up echocardiogram showed a 25% of EF. Patient recommended heart transplantation and transferred our hospital emergency room. He underwent sequential bilateral total hip arthroplasties using CoP bearing surfaces. At 12 years postoperatively, he presented to the other hospital with acute onset of left hip pain. He was diagnosed ceramic head fracture on his left hip. Head and liner change revision surgery was performed using Cobalt-Chrome alloy 28mm metal head and Protruded cross-linked polyethylene liners. In our hospital, the patient admitted cardiovascular department of internal medicine. Patient complained nonspecific fatigue and general weakness but had no other symptoms such as visual and hearing loss, cognitive dysfuction. During work-up, patient presented progressive left hip pain and complaint of discomfort for the mass on the left groin. He also complained Left leg weakness and numbness. Simple radiograph and enhanced CT study was done. Simple radiograph image shows radiodense area around the hip joint and radiologist suspected heterotopic ossification. The cardiovascular department consulted orthopedic department. In the image findings showed huge mass combined hemorrhagic component lining acetabular component extending psoas compartment and eccentric wear on cobalt-chrome alloy metal head. Also highly radiodense material was seen around neck inferor portion and severly deformed metal head was seen. It was highly suspected that metal related granuloma, which means severe metallosis. Performed heavy metals screen, cobalt levels were 397,800
We compared visible blood loss and calculated blood loss after bipolar hemiarthroplasty in femoral neck fracture, and evaluated correlation between blood loss and its risk factors. Materials and Methods: A total of 356 patients who underwent bipolar hemiarthroplasty in femoral neck fracture between 2004 and 2010 were enrolled in this study. The total blood loss was calculated using the formula reported by Mercuiali and Brecher. We analyzed several factors, including gender, age, body mass index (BMI), anesthesia method, cardiovascular and cerebrovascular disease, preoperative anemia, American Society of Anesthesiologists (ASA) score, use of cement, and use of antithrombotic agents. Results: Total calculated blood loss (1,408±72 ml) differed significantly from visible blood loss(980±102 ml). In addition, calculated blood loss differed between risk factors (1,526±369 ml in cardiovascular disease, 1,588±279 ml in general anesthesia, 1,645±920 ml in obesity, and 1,605±439 ml in use of antithrombotic agents). Conclusion: Total calculated blood loss was much greater than visible blood loss. Patients with risk factors such as cardiovascular disease, obesity, use of antithrombotic agents, and general anesthesia should be treated with care in order to reduce blood loss.Purpose
Children treated for osteosarcoma around the knee often have
a substantial leg-length discrepancy at skeletal maturity. The aim
of this study was to investigate the results of staged skeletal
reconstruction after a leg lengthening procedure using an external
fixator in these patients. We reviewed 11 patients who underwent staged reconstruction with
either an arthroplasty (n = 6) or an arthrodesis (n = 5). A control
group of 11 patients who had undergone wide excision and concurrent
reconstruction with an arthroplasty were matched for gender, location,
and size of tumour. We investigated the change in leg-length discrepancy,
function as assessed by the Musculoskeletal Tumor Society Scale
(MSTS) score and complications.Aims
Patients and Methods
Venous thromboembolism (VTE), including pulmonary embolism (PE) resulting from deep vein thrombosis (DVT), remains a well-known serious complication after femoral fractures. The low molecular heparin is widely used to prevent VTE. This study compared the effectiveness of VTE prevention between dalteparin and enoxaparin. From 2013 to 2014, we retrospectively recruited 712 patients who had femoral fractures with operative treatment. All patients receiving VTE chemoprophylaxis with perioperative period using dalateparin in Group 1(N=395) and enoxaparin in Group 2(N=317). The prophylactic dosing was determined using individual product labeling and identified as enoxaparin 40 mg every 12 hours and dalteparin 2500 international unit (IU) once daily, based on clinical practice guidelines. The prophylaxis was started at admission, and maintained during average 8.43.5 days after operation. The outcome including the incidence of clinically significant deep vein thrombosis, pulmonary embolism, perioperative bleeding and cost of drugs were evaluated between two groups.Introduction
Materials and Methods
The aim of the study was to develop a quantitative scoring system
to predict whether a large-to-massive rotator cuff tear was arthroscopically
reparable prior to surgery. We conducted a retrospective review of the pre-operative MR imaging
and surgical records of 87 patients (87 shoulders) who underwent
arthroscopic repair of a large-to-massive rotator cuff tear. Patients
were divided into two groups, based on the surgical outcome of the
repair. Of the 87 patients, 53 underwent complete repair (Group
I) and 34 an incomplete repair (Group II). Pre-operative MR images
were reviewed to quantify several variables. Between-group differences
were evaluated and multiple logistic regression analysis was used
to calculate the predictive value of significant variables. The
reparability index (RI) was constructed using the odds ratios of
significant variables and a receiver operating characteristic curve
analysis performed to identify the optimal RI cutoff to differentiate
between the two groups.Aims
Patients and Methods
The purpose of this study is to report the outcome of navigation-assisted cruciate-retaining total knee arthroplasty (TKA) using one type of cemented, second-generation, floating-platform (FP), mobile-bearing system. We retrospectively reviewed 42 patients (51 knees) who underwent cruciate retaining TKAs using e.motion-FP prostheses under navigational guidance. The preoperative diagnosis was osteoarthritis in all knees except one rheumatoid arthritis. There were 2 men (2 knees) and 40 women (49 knees) with a mean age of 64.0 ± 4.7 years (range, 51 – 76 years) at the time of index surgery. The mean follow-up was 120.0 months (range, 106 – 126 months). Clinical and radiographic results as well as mechanical survival rate of this type prosthesis were investigated at a mean follow-up of 10 years.Background
Methods
Arthroplasties of hip and knee are associated with blood loss, which may lead to adverse patient outcome. Jehovah's Witnesses do not accept blood transfusion. Performing arthroplasties in Witness patients without transfusion has been a matter of concern. We developed a protocol, which avoids transfusion in arthroplasties of Witness patients, and evaluated the feasibility and safety of the protocol. Our protocol consisted of subcutaneous administration of 4000 U recombinant erythropoietin and 100 mg of intravenous iron supplements when patient's hemoglobin level was less than 10 g/dL in preoperative evaluation. During the operation, cell saver, and plasma expander were used. Postoperatively, recombinant erythropoietin was administered three times a week and iron supplements were administered daily until the hemoglobin level reached 10 g/dL. We evaluated the feasibility of our protocol, perioperative complications and hematologic changes.Introduction
Materials and Methods
We sought to determine the 10-year survivorship of single-radius, posterior-stabilized total knee arthroplasty (TKA) in Asian patients. We also aimed to determine whether the long-term clinical and radiographic results differed between patients with and without patellar resurfacing. This retrospective study included 148 (115 patients) consecutive single-radius, posterior-stabilized TKAs. Ten-year survivorship analysis was performed using the Kaplan-Meier method with additional surgery for any reason as the end-point. Furthermore, long-term clinical and radiographic results of 109 knees (74%; 84 patients) with more than a 10-year follow-up were analyzed. Ten-year survivorship and long-term outcomes after surgery were determined, and outcomes were compared between patients with and without patellar resurfacing.Introduction
Materials and Methods
In comminuted intertrochanteric fractures, various operative options have been introduced. The purpose of this study was to determine whether there were differences in clinical and radiologic outcomes among bipolar hemiarthroplasty(BH), compression hip screw(CHS) and proximal femur nail antirotatory(PFNA) in treating comminuted intertrochanteric fractures(AO type, A2(21, 22, 23)) We retrospectively evaluated total 150 patients(BH:50, CHS:50, PFNA: 50) who were operated due to intertrochanteric fractures from March 2010 to Dec 2012 and were older than 65 years at the time of surgery. We compared these three groups for radiologic and clinical outcomes at 12 months postoperatively, including Harris hip score, ability of ambulation(Koval stage), visual analogue scale and radiologic limb length discrepancy(shortening). Landmark and radiologic length was checked.
–A: postoperative length –A’: POD 1year –B: immediate posteopative contralateral length(from hip center to distal tip of lesser trochanter) –B’: POD 1year contralateral length(from hip center to distal tip of lesser trochanter) –
Limb length(shortening) was adjusted considering difference of magnification = {A × (B’/B)}− A’Introduction
Materials and Methods
A number of studies have reported satisfactory
results from the isolated revision of an acetabular component. However,
many of these studies reported only the short- to intermediate-term
results of heterogeneous bearing surfaces in a mixed age group. We present our experience of using a ceramic-on-ceramic (CoC)
bearing for isolated revision of an uncemented acetabular component
in 166 patients (187 hips) who were under the age of 50 years at
the time of revision. There were 78 men and 88 women with a mean
age of 47.4 years (28 to 49). The most common reason for revision
was polyethylene wear and acetabular osteolysis in 123 hips (66%),
followed by aseptic loosening in 49 hips (26%). We report the clinical and radiological outcome, complication
rate, and survivorship of this group. The mean duration of follow-up
was 15.6 years (11 to 19). The mean pre-operative Harris hip score was 33 points (1 to 58),
and improved to a mean of 88 points (51 to 100) at follow-up. The
mean pre-operative total Western Ontario and McMaster Universities
Osteoarthritis Index score was 63.2 (43 to 91) and improved to 19.8
points (9 to 61) post-operatively. Overall, 153 of 166 patients
(92%) were satisfied with their outcome. Kaplan–Meier survivorship
analysis, with revision or radiological evidence of implant failure
(13 patients, 8%) as end-points, was 92% at 15 years (95% confidence
interval 0.89 to 0.97). Isolated revision of a cementless acetabular component using
a CoC bearing gives good results in patients under 50 years of age. Cite this article:
We investigated the spinopelvic morphology and
global sagittal balance of patients with a degenerative retrolisthesis
or anterolisthesis. A total of 269 consecutive patients with a degenerative
spondylolisthesis were included in this study. There were 95 men
and 174 women with a mean age of 64.3 years ( A backward slip was found in the upper lumbar levels (mostly
L2 or L3) with an almost equal gender distribution in both the R
and R+A groups. The pelvic incidence and sacral slope of the R group
were significantly lower than those of the A (both p <
0.001)
and R+A groups (both p <
0.001). The lumbar lordosis of the R+A
group was significantly greater than that of the R (p = 0.025) and
A groups (p = 0.014). The C7 plumb line of the R group was located
more posteriorly than that of the A group (p = 0.023), but was no
different from than that of the R+A group (p = 0.422). The location
of C7 plumb line did not differ between the three groups (p = 0.068).
The spinosacral angle of the R group was significantly smaller than
that of the A group (p <
0.001) and R+A group (p <
0.001). Our findings imply that there are two types of degenerative retrolisthesis:
one occurs primarily as a result of degeneration in patients with
low pelvic incidence, and the other occurs secondarily as a compensatory
mechanism in patients with an anterolisthesis and high pelvic incidence. Cite this article:
The success of total knee arthroplasty depends on many factors, including the preoperative condition of the patient, the design and materials of the components and surgical techniques. It is important to position the femoral and tibial components accurately and to balance the soft tissues. Malpositioning of the component can lead to failures due to aseptic loosening, instability, polyethylene wear and dislocation of the patella. In order to improve post-operative alignment, computer-aid systems have been developed for total knee arthroplasty. Many clinical and experimental studies of these systems have shown that the accuracy of implanted components can be improved in spite of the increase in costs and operating time. This may not, however, improve the outcome in the short-term. Restoration of the normal mechanical axis of the knee and balancing of the surrounding soft tissues have been shown to have an important bearing on the final outcome of knee replacement operations. In severely deformed knees, whether varus or valgus, these goals may be difficult to achieve. We compared the radiologic results of the mechanical axis and implant position of Total Knee Arthroplasty using a robot-assisted method with conventional manually implanted method in severe varus deformed knee. A data set of 50 consecutive cases that were performed from April 2007 to December 2010 using the robot assisted TKA(Group A) were compared with a data set of 50 consecutive cases from the same period that were done using conventional manual TKA(Group B). All cases had a preoperative mechanical varus deformity >15° and one brand of implant was used on all cases. The diagnosis was primary osteoarthritis in all knees. The operations were performed by one-senior author with the same robot system, ROBODOC (ISS Inc., CA, USA) along with the ORTHODOC (ISS Inc., CA, USA) planning computer. (See Figure 1.) The radiological evaluations included mechanical axis, implant position (α,β,γ,δ angle) according to the system of American Knee Society.Introduction
Materials and Methods
Since Smith-Peterson's glass mold arthroplasty in 1939, hip resurfacing arthroplasty was developed and introduced to orthopaedic surgery field but it had many problem like early loosening. Recently it is being popular for some indication as development of new implant design and manufacturing. There are still many suggested advantages of hip resurfacing arthroplasty. These include bone conservation, improved function as a consequence of retention of the femoral head and neck and more precise biomechanical restoration, decreased morbidity at the time of revision arthroplasty, reduced dislocation rates, normal femoral loading and reduced stress-shielding, simpler management of a degenerated hip with a deformity in the proximal femoral metaphysic, an improved outcome in the event of infection, and a reduced prevalence of thromboembolic phenomena as a consequence of not using instruments in the femur. But, there are limited or inconsistent data to support some of these claims regarding the benefits of hip resurfacing including the potential for a more natural feel because of the minimal disturbance of the proximal part of the femur resulting in a better and faster functional outcome. We evaluate the short term results of hip resurfacing arthroplasty using custom patient-specific tooling for prosthesis placement for better standardization. 40 cases, 36 patients(male:20, female:16) those of who were candidates of a Hip Resurfacing procedure, participated in the study. Mean follow up period was 2.5 years (8 months ∼3 years). A CT scan was performed on each patient and a 3D model was generated using the computer tomography dataset. From this model a bone-surface skin was extracted and this data set was used to create a personalized jig. Detailed analysis of the native bone structure was then used to preoperatively plan the appropriate size and position of the implant. A mean 7 degree corrective valgus angle was prescribed on all cases. Postoperative radiological datasets were superimposed onto preoperative plan position and offsets were measured. Operative times were recorded per step during the procedure. Surgeon comfort and ease of use was also noted.Introduction
Materials and Methods
No study compared the clinical results of the posterior-stabilized mobile-bearing knee with those of nonposterior-stabilized mobile-bearing knee in the same patients. The purpose of this study was to examine whether the clinical and radiographic results, range of motion, patients satisfaction, and complication rates would be better in the knees with a posterior-stabilized mobile-bearing knee than in the knees with a nonposterior-stabilized mobile-bearing knee. One hundred and fourteen patients (mean age, 67.9 years) received a nonposterior-stabilized mobile-bearing knee prosthesis in one knee and a posterior-stabilized mobile-bearing knee prosthesis in the contralateral knee. Seven patients were men, and 107 were women. At the time of each follow-up (mean, 7.3 years; range, seven to 7.6 years), the patients were assessed clinically and radiographically.Background
Methods
Despite many claims of good wear properties following
total knee replacement (TKR) with an oxidised zirconium (OxZr) femoral
component, there are conflicting clinical results. We hypothesised
that there would be no difference in either the mid-term clinical
and radiological outcomes or the characteristics of the polyethylene
wear particles (weight, size and shape) in patients using an OxZr
or cobalt-chrome (CoCr) femoral component. In all 331 patients underwent
bilateral TKR, receiving an OxZr femoral component in one knee and
a CoCr femoral component in the other. The mean follow-up was 7.5
years (6 to 8). Following aspiration, polyethylene wear particles
were analysed using thermogravimetric methods and scanning electron
microscopy. At the most recent follow-up, the mean Knee Society
score, Western Ontario and McMaster Universities Osteoarthritis
Index score, range of movement and satisfaction score were not significantly
different in the two groups. The mean weight, size, aspect ratio
and roundness of the aspirated wear particles were similar for each
femoral component. Survivorship of the femoral, tibial and patellar
components was 100% in both groups. In the absence of evidence of an advantage in the medium term
we cannot justify the additional expense of an OxZr femoral component.
The purpose of this study was to evaluate the
long-term functional and radiological outcomes of arthroscopic removal
of unstable osteochondral lesions with subchondral drilling in the
lateral femoral condyle. We reviewed the outcome of 23 patients
(28 knees) with stage III or IV osteochondritis dissecans lesions
of the lateral femoral condyle at a mean follow-up of 14 years (10
to 19). The functional clinical outcomes were assessed using the Lysholm
score, which improved from a mean of 38.1 ( We found radiological evidence of degenerative changes in the
third or fourth decade of life at a mean of 14 years after arthroscopic
excision of the loose body and subchondral drilling for an unstable
osteochondral lesion of the lateral femoral condyle. Clinical and
functional results were more satisfactory.
The purpose of this prospective, randomised study
was to evaluate the clinical and radiological results comparing the
identical cemented or cementless NexGen total knee prostheses implanted
bilaterally in the same patient. Sequential simultaneous bilateral
total knee replacements were performed in 50 patients (100 knees).
There were 39 women and 11 men with a mean age of 58.4 years (51
to 67) who received a cemented prosthesis in one knee and a cementless
prosthesis in the other. The mean follow-up was 13.6 years (13 to
14). At final review, the mean Knee Society scores (96.2 (82 to
100)
This study aims to identify the efficiency of biomechanical and bioactive properties of the bovine cortical bone cage treated with conditionally surface demineralization. The procured bovine femoral bones were got rid of lipid, protein, and blood materials by chemical process such as 3% hydrogen peroxide and 70% ethanol. The long shaft bones were cut by band saw. Several bone cages were processed by milling machine. The cortical bone cages were demineralized by 0.6N HCl treatment with various conditions, which were the tendency of HCl treatment time, position, direction. After neutralization with pH 7.0, phosphate buffered saline washing and freeze drying process, the vial vacuum packed bone cages were sterilized by 25kGy gamma irradiation. The SEM and EDS system were proceeded for morphology and Ca content in various layers of bone cage. In vitro test for cell viability and differentiation, extracted supernatant from each bone cage by tissue culture was treated in MC3T3E1 cells. For indentifying releasing materials, the others were carried for quantitative analysis by ELISA. After each conditioned period, mRNA expression was compared by RT-PCR. The axial compression and bending strength were measured by universal testing machine (UTM) for biomechanical property. Between the outer layer and inner layer of bone cage for 2 hour’s HCl, there was concentrated Ca extracted layer. The tendency of Ca content and direction of demineralised treatment had effects on the compression and elastic strength. In vitro test, initial Osteogenic transcription factor’s mRNA expression and quantitative result of releasing material had rewarding regulation by HCl-treatment time and treated direction. Conditionally surface demineralized bone cage had good osteoconduc-tivity and osteoinductivity for spinal interbody fusion.
We performed a prospective study to examine the
influence of the patient’s position on the location of the abdominal
organs, to investigate the possibility of a true lateral approach
for transforaminal endoscopic lumbar discectomy. Pre-operative abdominal
CT scans were taken in 20 patients who underwent endoscopic lumbar discectomy.
Axial images in parallel planes of each intervertebral disc from
L1 to L5 were achieved in both supine and prone positions. The most
horizontal approach angles possible to avoid injury to the abdominal
organs were measured. The results demonstrated that the safe approach
angles were significantly less (i.e., more horizontal) in the prone
than in the supine position. Obstacles to a more lateral approach
were mainly the liver, the spleen and the kidneys at L1/2 (39 of
40, 97.5%) and L2/3 (28 of 40, 70.0%), and the intestines at L3/4
(33 of 40, 82.5%) and L4/5 (30 of 30, 100%). A true lateral approach
from each side was possible for 30 of the 40 discs at L3/4 (75%)
and 23 of the 30 discs at L4/5 (76.7%). We concluded that a more
horizontal approach for transforaminal endoscopic lumbar discectomy
is possible in the prone position but not in the supine. Prone abdominal
CT is more helpful in determining the trajectory of the endoscope.
While a true lateral approach is feasible in many patients, our
study shows it is not universally applicable.
We reviewed the results of 84 total hip replacements performed with a short metaphyseal-fitting anatomical cementless femoral component in 84 unselected consecutive patients with a mean age of 78.9 years (70 to 88). The mean follow-up was 4.6 years (4 to 5). The mean pre-operative Harris hip score was 26 points (0 to 56), which improved to 89 (61 to 100) at the final follow-up. No patient had thigh pain. The mean pre-operative Western Ontario and McMaster Universities osteoarthritis index score was 61 points (48 to 75), which improved to 21 (6 to 46). The mean University of California, Los Angeles activity score was 5.5 points (3 to 7) at the final follow-up. Osseointegration was seen in all femoral and acetabular components. All hips had grade 1 stress shielding of the proximal femur. No acetabular or femoral osteolysis was identified. These results demonstrate that a short metaphyseal-fitting femoral component achieves optimal fixation without diaphyseal anchorage in elderly patients.
There have been comparatively few studies of the incidence of osteolysis and the survival of hybrid and cementless total hip replacements (THRs) in patients younger than 50 years of age. We prospectively reviewed 78 patients (109 hips) with a hybrid THR having a mean age of 43.4 years (21 to 50) and 79 patients (110 hips) with a cementless THR with a mean age of 46.8 years (21 to 49). The patients were evaluated clinically using the Harris hip score, the Western Ontario and McMaster Universities (WOMAC) osteoarthritis score and the University of California, Los Angeles (UCLA) activity score. Radiographs and CT scans were assessed for loosening and osteolysis. The mean follow-up was for 18.4 years (16 to 19) in both groups. The mean post-operative Harris hip scores (91 points Although the long-term fixation of the acetabular metallic shell and the cemented and cementless femoral components was outstanding, wear and peri-acetabular osteolysis constitute the major challenges of THR in young patients.
Our aim was to determine the success rate of repeated debridement and two-stage cementless revision arthroplasty according to the type of infected total hip replacement (THR). We enrolled 294 patients (294 hips) with an infected THR in the study. There were 222 men and 72 women with a mean age of 55.1 years (24.0 to 78.0). The rate of control of infection after the initial treatment and after repeated debridement and two-stage revisions was determined. The clinical (Harris hip score) and radiological results were evaluated. The mean follow-up was 10.4 years (5.0 to 14.0). The eventual rate of control of infection was 100.0% for early superficial post-operative infection, 98.4% for early deep post-operative infection, 98.5% for late chronic infection and 91.0% for acute haematogenous infection. Overall, 288 patients (98%) maintained a functioning THR at the latest follow-up. All the allografts appeared to be united and there were no failures. These techniques effectively controlled infection and maintained a functional THR with firm fixation in most patients. Repeated debridement and two-stage or repeated two-stage revisions further improved the rate of control of infection after the initial treatment and increased the likelihood of maintaining a functional THR.
Hyaluronic acid (Hyalunan, HA), β-1,4-linked D-glucuronic acid and β-1,3 N-acetyl-D-glucosamine polysaccharide, is a nonsulfated glycosaminoglycan(GAG) conserved in the extracellular matrix (ECM). Due to its biocompatibility, biodegradable properties, HA is widely applied for tissue engineering. However, HA also has defects for tissue engineering such as mechanical properties, difficulty of handling. Thus, it is various modified by chemical reaction to produce HA derivative. HA plays an important role in tissue morphogenesis, proliferation and cell differentiation. Ascorbic acid (AA) has an effect on collagen synthesis and bone mineralization. Ascorbate levels also have a significant effect on osteoblast proliferation and alkaline phosphatase (ALP) expression. However AA is weak to heat and light, thus it is easily degradable. Consequently, we conjugated HA with AA in order to make it more stable and effective. In this study, we prepared HA-AA conjugate and evaluated activity of products in pre-osteoblast. To produce more effective conjugation, we synthesised HA derivative, HA-N-hydroxysuccinimide, an activated ester of the glucuronic acid moiety. This HA-active ester intermediate is a precursor for drug-polymer conjugates. The degree of substitution was calculated by NMR analysis. The modified HA was dialysed and lyophilised. The yield of conjugation is calculated by Gel Permeation Chromatography (GPC). After the process, HA was conjugated with AA once again as previously mentioned. In this study, the resultant HA-AA conjugate was tested on MC3T3-E1, murine pre-osteoblast cells. We examined cellular viability (cytotoxicity), proliferation and gene expression. The expression of Type 1 collagen was examined by RT-PCR and western blot. Osteocalcin (OCN), osteopontin (OPN) and bone sialoprotein (BSP), bone proliferation and differentiation marker were detected by RT-PCR. Alkaline phosphatase assay was also performed. For confirmation on bone mineralization, alizarin red staining and von Kossa staining was performed. In conclusion, the in vitro data demonstrate that HA-AA conjugate has an important role in bone formation, as it can increase proliferation and osteogenic differentiation of MC3T3-E1 cells. These observations further support the use of in vivo system for tissue engineering applications.
Although epigallocatechin-3-O-gallate (EGCG), the predominant catechin from tea, has various pharmacological and biological activities including anti-carcinogenic, anti-thrombotic and anti-inflammatory effects, relatively a little is known about its beneficial effects on the non-frozen preservation of mammalian cells and tissues. In the present study, a storage solution containing EGCG was employed to testify the hypothesis that cold preservation of osteochondral allografts was attributed to EGCG-mediated reversible regulation of cell cycle. Human articular cartilages were obtained from knee joints of 10 patients (58 – 86 years old) undergoing total knee arthroplasty at Marunouchi Hospital, Matsumoto, Japan. Cartilage specimens were procured by osteotome under sterile conditions from the donor and placed in saline for 1 hr until the end of surgery. Immediately after surgery, the specimens were transferred in a storage solution (serum-free RPMI 1640 media with 1% antibiotic-antimycotic solution without or with 1 mM EGCG) and kept at 4°C. The specimens were then delivered to the senior author (Prof. Hyon) within 1 day from procurement. Additionally, fresh cartilages were delivered in a complete media with 10% fetal bovine serum at room temperature after procurement from the donor. Because of this necessary processing delay between tissue procurement from the donor and its delivery, 1 day was set as the data point for the fresh specimen. All procedures involving human subjects received prior approval from Marunouchi Hospital, Osaka City University Graduate School of Medicine and the Institutional Review Board of Institute for Frontier Medical Sciences, Kyoto University, and all subjects providing written informed consent. On receipt of the cartilage tissues, the specimens were replaced with either 20 ml of a storage solution without or with EGCG and then stored at 4°C for 1, 2 and 4 wk. At the end of each storage period, chondrocyte viability (CCK-8 assay), biochemical and immunohistochemical composition [glycosaminoglycans (GAG) and (type II) collagen], and biomechanical property (compressive elastic modulus) were assessed. The regulatory effects of EGCG on cell cycle distribution as well as expression levels of cyclins (CCNs) and nuclear factor-κB (NF-κB) were also investigated in articular chondrocytes. Chondrocyte viability of cartilages preserved with EGCG was significantly well-maintained for at least 2 weeks with high contents of GAG and total collagen. These beneficial effects of EGCG were confirmed by histological and immunohistochemical observations showing well-preserved cartilaginous structures and delayed denaturation of extracellular matrices. The compressive elastic modulus of cartilages preserved with EGCG was almost in the same range as that of fresh ones. Moreover, the penetration of FITC-conjugated EGCG into the matrices of cartilages and its incorporation into the cytosol of cells in lacunae were observed. Increased cell population at the G0/G1 phase by EGCG returned to the normal level after EGCG removal, whereas decrease at the G2/M phase did not. Negatively regulated expression of CCND1, CCNE2 or NF-κB in EGCG-treated cells was restored by removing EGCG, but not CCNA2 and CCNB1. It is suggested that EGCG play effective roles in preserving articular cartilages by reversibly regulating cell cycle at G0/G1 phase and NF-κB expression.
The purpose of the study was to evaluate clinical outcomes in patients receiving saphenous neurocutaneous island flaps for reconstruction of soft tissue defects after total knee arthroplasty (TKA). Four patients (2 men, 2women; mean age 61 years) with post-TKA soft tissue defects were treated with saphenous neurocutaneous island flaps between November 2001 and August 2007. The mean follow-up period was 3.5 years. Initial diagnoses were traumatic arthritis, rheumatoid arthritis, arthritis due to previous osteomyelitis and tuberculous arthritis. One patient developed deep infection after TKA, so revision TKA with Nexgen® LPS (Legacy® posterior stabilized) was performed after soft tissue reconstruction. One soft tissue defects developed after TKA with Nexgen® LPS due to long-term steroid use for rheumatoid arthritis. Two cases occurred after placement of Nexgen® LCCK (Legacy® constrained condylar knee). Two cases developed secondary to diabetes mellitus and tuberculous arthritis. Soft tissue defects were located over the patella (1 case), patellar tendon (1 case), and medial side of the knee (2 cases). The flaps ranged in size from 0.03×0.004 m to 0.08×0.05 m. All flaps were proximally based. All flaps survived completely. The postoperative range of motion was between 3° and 100°. Because saphenous neurocutaneous island flaps are well matched with local tissue and are tough, thin, pliable and sensate, they are an ideal option for reconstruction of soft tissue defects after TKA.
Risk of impingement after total hip resurfacing arthroplasty may be great because femoral head-neck unit is preserved and there is little flexibility to adjust limb length and femoral offset, but this potentially worrisome phenomenon has been rarely reported. Impingement between femoral neck and acetabular cup was observed in a cohort of patients who underwent contemporary total hip resurfacing arthroplasty. We then questioned whether patient demographics, component features or suboptimal position of components would be risk factors for impingement. We reviewed a consecutive series of 51 patients (61 hips) who underwent contemporary total hip resurfacing arthroplasty. The mean age at the time of the index arthroplasty was 38 years (18 to 64). The most common diagnosis leading to the total hip resurfacing arthroplasty was osteonecrosis of the femoral head in 41 hips (67%). All the procedures were performed by single surgeon through an anterolateral approach. All the patients were assessed clinically and radiographically at a mean of 32 months (24 to 53) postoperatively. Femoro-acetabular cup impingement, defined as the presence of bony spur at the femoral neck corresponding to abutment site of the metallic cup, was observed in seven of the 61 hips (11.5%). Of these, five patients reported limitation of activities due to groin pain. The average postoperative Harris hip score of impingement hips was inferior to those of non-impingement hips (p = 0.004). No significant difference was detected between the impingement hips and non-impingement hips with regard to of patient demographics, component features and radiographic measurements including cup inclination, cup version, femoral component version, anterior femoral offset, stem-shaft angle, femoral offset and limb length discrepancy. Our multivariate analysis revealed that only acetabular cup uncoverage ratio had a significant association with femoro-acetabular cup impingement (p = 0.04, odds ratio 1.385 [95% CI, 1.014 – 1.891]). There was no aseptic loosening of components or femoral neck fracture. We found a high incidence of impingement between retained femoral neck and metallic acetabular cup after contemporary total hip resurfacing arthroplasty in association with an increased acetabular cup uncoverage ratio. As patients with femoro-acetabular cup impingement showed inferior clinical results, it is crucial to avoid excessive protrusion of acetabular cup beyond bony margin by proper selection of acetabular component size and appropriate positioning.
Many reports show good results following procedures, such as intervertebral body fusion using cage or total disc replacement, that restore adequate disc height. However, there have been no references regarding the range of normal lumbar disc height in Korean adults which can be used as a standard for the implant size. The purpose of our study is to measure the lumbar disc height on radiographs in normal Korean. 132 subjects (age range 20 to 40 years) who had no previous history of low back pain and no significant finding on physical examination were enrolled. Plain lateral lumbar spine radiograph in supine position were taken. Intervertebral disc heights were measured at anterior, middle and posterior portion of each lumbar disc. The average magnification rate was 115%, and the disc heights were corrected by the magnification rate in each segment. Lumbar disc height showed cranio-caudal pattern in both male and female groups. L4–5 disc heights were highest at anterior, middle and posterior portion in male. L4–5 disc heights were highest at middle and posterior portion in female. L5-S1 disc height was highest at anterior portion in female, but there was no statistically significant difference between L4–5 and L5-S1 disc height at anterior portion. There was no significant difference in disc height between male and female except anterior portion of L1–2 and L2–3 disc. Statistically significant decrease in disc height was not presented in overweight person at all measured site in male and female except posterior portion of L1–2 disc in male. This research is meaningful in that it is an attempt to provide a reference value of lumbar disc height in Korean adults, and the measured values may also be useful in manufacturing Korean modeled artificial lumbar disc prosthesis or surgical instruments for lumbar interbody fusion.
Cervical arthroplasty is usually performed for the treatment of soft disc herniation, but not for spondylotic radiculopathy. To our knowledge, there has no study to investigate the clinical and radiological results of cervical arthroplasty for spondylotic radiculopathy. We therefore performed the current study to evaluate clinical and radiological results of cervical arthroplasty for spondylotic radiculopathy with severe narrowing of the intervertebral disc space. Eight patients, who underwent anterior decompression, overdistraction, and implantation of artificial cervical disc for primary, single-level spondylotic radiculopathy with severe narrowing of the disc space (decrease more than 50% of adjacent disc spaces) were included in this study. Four were male and 4 were female with mean age of 49.5 years. The operation level was 7 C5–6 and 1 C6–7. Five Prodisc-C and 3 Prestige LP prostheses were implanted. The clinical and radiological evaluations were performed with minimum one year follow-up (range, 12 – 19 months) after surgery. VAS of the neck and arm pain improved (79.6 vs. 19.4 points, p <
0.01; 82.5 vs. 22.7 points, p <
0.01) at last follow-up, respectively. According to Odom’s criteria, satisfactory clinical outcome was achieved in 63% (5 out of 8, 3 excellent and 2 good) while fair result was achieved in 37% of the patients (3 out of 8). The disc space (3.0mm vs. 6.4mm, p <
0.01) and range of motion (1.4 vs. 6.3 degrees, p = 0.009) at the operated level increased, respectively. Overall sagittal alignment of the cervical spine was increased after surgery (5.2 vs. 11.3 degrees, p <
0.05). In 5 patients, segmental angle of the operated level was increased (0.2 vs. 5.3 degrees, p = 0.003) after surgery with maintained facet joint articulation overlap. However, in 3 patients, segmental angle of operated level became kyphotic from neutral (0 vs. −10.0 degrees, p = 0.295) with decreased facet joint articulation overlap. In conclusions, cervical arthroplasty provided favorable clinical and radiological outcomes in most of the patients with spondylotic radiculopathy and severe narrowing of the disc space at minimum one year follow-up after surgery. However, in some of the patients, postoperative segmental kyphosis developed and clinical outcomes were not satisfactory.
Modular femoral stem provides significant flexibility in total hip revision arthroplasty. There have been few clinical studies that have dealt with modular stem. We have evaluated the clinical and radiographic performance of 59 patients with distal fix modular Link MP stem. The average follow-up period was 6.4 years. The average Harris hip score was improved from 47 to 87.6. Of 19 patients with trochanteric osteotomy, greater trochanter was displaced in four patients. Re-revision was done to five patients. Three were for subsidence, one of them showed dissociation of the coupling part and the other two were for a nonunion of osteotomy site. There was no statistical relation (p=0.40) between stem subsidence and bone deficiency; the subsidence may have been too small for the canal. As a result of last follow-up, survival rate was 91.5 %(CI 95%, 89–101), but there was no case of recurrent dislocation or femoral stem fracture.
Two-stage reimplantation is currently the most widely accepted method of treatment for a periprosthetic hip infection. However, it remains controversial whether the treatment protocol may be equally effective in the eradication of resistant microorganisms. We compared the results of two-stage reimplantation performed for periprosthetic hip infection caused by resistant microorganisms with those performed for periprosthetic hip infection caused by non-resistant microorganisms. We reviewed a consecutive series of 32 patients (32 hips) who had a culture-proven deep infection at the site of hip arthroplasty and were treated by a two-stage reimplantation protocol. Based on the antibiotic sensitivities of the infecting microorganisms, the patients were divided into two groups. Resistant microorganism group consisted of 20 patients who had an infection with antibiotic-resistant bacterial strains (methicillin-resistant Staphylococcus aureus in 11 and methicillin-resistant Staphylococcus epidermidis in 9). Non-resistant microorganism group consisted of 12 patients who had an infection with antibiotic-sensitive bacterial strains. The treatment was considered a failure if the patient had a persistent infection after the first-stage procedure or a recurrence of infection after reimplantation. The mean duration of follow-up after the index procedure was 45 months (24 to 123). Among the entire series of the 32 patients, the second-stage reimplantation was able to be performed in 29 patients (91%) and the remaining three went on to a permanent resection of the hip because of persistent infections. After the two-stage reimplantation, four patients had a recurrence of infection (relapse of infection with the same microorganism in three and reinfection with different resistant microorganism in one). Thus, overall treatment failure rate was 22% and all these failures occurred among patients with resistant microorganisms. Treatment failure rate of 35% in resistant microorganism group was significantly higher than that of 0% in the non-resistant microorganism group (p = 0.029). None of the variables evaluated in this study was found to be significantly associated with the treatment failure in the resistant microorganism group. Current two-stage reimplantation protocol showed a high rate of treatment failure in our patients who had periprosthetic hip infection caused by methicillin-resistant bacterial strains. Further study is needed to develop optimal treatment strategy for this difficult-to-treat condition.
Metal-on-metal bearing was re-introduced with the aim of eliminating polyethylene wear and resulting complications of osteolysis and aseptic loosening in total hip arthroplasty (THA). However, authors of recent studies have reported periprosthetic osteolysis and aseptic failure following second-generation metal-on-metal THA. The purpose of this study is to report the results at a minimum of five years following cementless total hip arthroplasty with a contemporary metal-on-metal articulation. Our study included findings of histologic examination on periprosthetic tissues from revised hips and wear and roughness analysis of retrieved implants. A consecutive series of 158 cementless THAs that were performed in 154 patients using a contemporary metal-on-metal bearing were assessed at a mean of 6.5 years (5 to 8). Their mean age at surgery was 53 years (21 to 80). The patients were assessed clinically with use of the Harris hip score, and the hips were assessed radiographically. Histological analysis was performed on specimens retrieved from the revised hips, and wear and roughness measurements were made for the explanted prostheses. The average Harris hip score improved from 45 points preoperatively to 92 points at the final follow-up examination. There was no aseptic loosening of the femoral or acetabular components. One hip was revised because of recurrent dislocation and one was managed with two-stage re-implantation for deep infection. Thirteen hips (8%) had osteolysis; 11 had osteolysis localized within the greater trochanter and two had both femoral and ace-tabular osteolysis. Of these, five patients who had a persistent pain and osteolysis underwent revision operation for the consideration of bearing exchange to a ceramic-on-ceramic or ceramic-on-polyethylene combination. All these revised hips showed extensive synovial-like tissue hypertrophy and perivascular infiltration of lymphocytes on histological examinations. Annual volumetric wear rate measured on one retrieved femoral head was 1.04mm3/yr, and roughness measured on three retrieved femoral heads was consistently very low between 8nm and 117nm. After the revision surgery, all the patients noticed disappearance of pain as well as radiographic evidence of healing of the osteolytic lesion. Our mid-term follow-up of cementless THA using a contemporary metal-on-metal bearing revealed an unexpectedly high rate of periprosthetic osteolysis possibly in association with metal hypersensitivity. In patients with persistent hip pain and osteolysis after contemporary metal-on-metal THA, surgeons should consider an exchange of the articulation surface to a ceramic-on-ceramic or ceramic-on-polyethylene combination because they can be cured only after an elimination of the source of hypersensitivity reaction.