Background: A common clinical scenario encountered by an orthopaedic surgeon is a patient with a secure cementless acetabular shell and a failed polyethylene liner. One treatment option is to cement a new liner into the fixed shell. The purpose of this study was to evaluate the radiographic outcome of this technique.

Materials and Methods: From November 2001 to April 2006, 11 liner were cemented into well-fixed cementless acetabular shell of 10 patients. There were 6 males and 5 women of average age 54.3 (range 41~73) years at the time of the revision surgery. The indication for the revision procedure were aseptic loosening and wear in 9 cases, and periprosthetic fracture in 2 cases. The pre-existing screws in the shell were removed, and screw holes were filled with allogenic bone graft or cementaion. The patients were evaluated the radiographic evidence of progressive loosening and osteolysis. The average follow up period was 35.2 (range 24~76) months.

Results: There were no changes in cup and liner position or progression of osteolytic lesion around the femoral or acetabular components in the last follow-up radiographs. No compications such as a deep or superficial infection or deep vein thrombosis occurred. There were no hip dislocations.

Conclusion: A liner cemented into a secure, well-positioned cementless acetabular shell provide stability and durability at short and long term follow up. This technique also has advantages of preventing bone loss associated with removal of a well fixed component, and lower surgical morbidity and more liner options. Careful attention to the preparation of the liner, the sizing of the component, and the cementing technique are likely to reduce the failure of this construct.

Background: There area some controversies about the need for revision of well fixed femoral stem during the revision total hip arthroplasty. The purpose of this study is to evaluate the state of unretrieved femoral stem, in revision total hip arthroplasty where only acetabular component was revised.

Methods: From January 1998 to December 2004, thirty-one patients underwent revision total hip arthroplasty whose well fixed femoral stem was retained and acetabular components revised. Twenty-six patients(29hips) with a minimum follow-up of three years were included in this study. Out of those twenty-six patients, sixteen patients(18hips) were male and ten patients(11hips) were female with an average age of 54.3 years for the study group. The average time from the primary operation until the revision surgery was 9.2 years and the average follow-up period after the revision was 5 years. The femoral head component was exchanged in all cases and same size femoral head component was used in eleven hips. The clinical results wee analyzed using Harris Hip Score, and the radiographs were reviewed for stability of acetabular components, femoral stem, and degree of osteolysis and radiolucent lines.

Results: The average Harris Hip score improved from 56.3 points preoperatively to 89.8 points postoperatively. Femoral stems were found to be stable in all hips. Sixteen hips(55.2%) showed evidence of osteolysis and seven hips(24.1%) showed non-progressive radiolucent lines. The osteolysis was detected at Gruen Zone I and VII in most of the affected hips except for two hips which showed distal osteolysis. The average life of femoral stem from primary operation until the final follow up varied from 10.8 years to 18.2 years, with the average being 14.2 years.

Conclusions: We recommended that well fixed, stable femoral components can be retained at the time of revision total hip arthroplasty.

Level of evidence: Therapeutic Level IV

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.

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.

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.

Introduction: Cement augmentation of osteoporotic vertebral fractures by vertebroplasty can alleviate pain, possibly by restoring normal load-sharing to the affected motion segment. Fracture is known to decrease vertebral compressive stiffness (1), and also affects the compressive stress distribution acting on the vertebral body, causing stress concentrations to appear in the adjoining intervertebral discs (2). We hypothesise that vertebro-plasty can reverse these fracture-induced changes.

Methods: Nineteen cadaver thoraco-lumbar motion segments (64–90 yrs) were used. Each was mounted on a hydraulic materials testing machine and induced to fracture by compressive overload in moderate flexion. Vertebroplasty was performed by injecting 7 cc of poly-methylmethacrylate cement (Simplex P, Stryker Howmedica, NJ) into the fractured vertebral body. Specimens were then creep loaded at 1.5 kN for 1 hour to allow consolidation. Before and after each procedure, profiles of the compressive stress distribution were obtained by pulling a miniature pressure transducer along the mid-sagittal diameter of the intervertebral disc whilst it was compressed at 1.5kN. Using these profiles, stress peaks in the anterior and posterior annulus were measured by subtracting the nucleus pressure from the peak stress in each region (2). Compressive stiffness of the motion segment was also measured before and after vertebroplasty from the tangent of the load-displacement curve at 1 kN. Changes were compared using ANOVA.

Results: Following fracture, motion segment compressive stiffness was reduced by 37% from 2478 N/mm, STD 966N/mm, to 1583 N/mm, STD 585 N/mm (p = 0.0001), stress peaks in the posterior annulus were increased by 139% from 0.24 MPa, STD 0.24 MPa, to 0.57 MPa, STD 0.47 MPa (p = 0.016), and stress peaks in the anterior annulus showed no significant change. The decrease in compressive stiffness was significantly correlated with the increase in the size of the posterior stress peak (Rsq = 0.65, p< 0.001). Following vertebroplasty and subsequent creep loading, compressive stiffness was increased to 2156 N/mm, STD 718 N/mm, and stress peaks in the posterior annulus were reduced to 0.31 MPa, STD 0.43 MPa. These changes were again highly correlated with each other (Rsq = 0.68, p< 0.001). Both compressive stiffness and the size of posterior stress peaks after vertebroplasty showed no significant difference when compared to pre-fracture values.

Discussion: Fracture reduces the ability of vertebrae to resist deformation, thereby decreasing compressive stiffness. These changes impair the disc’s ability to press evenly on the vertebral body, giving rise to increased stress peaks in the posterior annulus. Vertebroplasty can reverse these fracture induced changes by increasing vertebral compressive stiffness which acts to restore pressure in the nucleus. This enables the disc to press more evenly on the vertebral body and thereby reduces the size of stress peaks in the posterior annulus. This restoration of normal load-sharing may possibly contribute to pain relief in patients undergoing this procedure.

Introduction: A retrospective study of the clinical and radiographic results of the Mallory-Head total hip arthroplasty was conducted.

Materials and Methods: Sixty-seven patients (76 hips) with a mean age of 50 years who had Mallory-Head total hip arthroplasty were studied. The mean follow-up period was 10.1 years (9–13years).

Results: Excellent or good clinical results were found in 64 patients. Minimal thigh pain was found in 3 patients (4.4%). Seventy-one hips (93.4%) showed fixation by bony ingrowth and three (3.9%) showed the stable fibrous fixation. Bony on and ingrowth was also observed in 16 hips (21%) at distal smooth and of the grit-blast area. Two femoral components were revised: one for subsidence, and the other for the recurred infection. Therefore, the success rate was 97.3%.

Conclusion: The authors believe that these good results are a consequence of excellent bony ingrowth on the proximal two-thirds of the femoral surface area. In conclusion, proximal plasma-spray coating and tapered shape of the Ti-stem showed excellent bony ingrowth and initial stability. Our results indicate that distal tapered shape may be an important element in the design of cementless stems.

Introduction: Hyperlipidemia is related to hypercoagulability and hypofibrinolysis, which may cause a tendency to intravascular thrombosis and result in osteonecrosis (ON). Recently PPARs were confirmed to induce adipocyte differentiation, and fatty acids were identified as the transcriptional effectors for PPARs, which may cause the hyperlipidemia and fatty marrow. The aim of this study was to identify whether the adipocytic differentiation was increased in the bone marrow obtained from the femoral head in patients with osteonecrosis.

Materials and Methods: A lipid profile (cholesterol, triglyceride, LDL, and free fatty acid) was performed for patients with osteonecrosis of the femoral head. The PPARγ2 expression was checked as to whether the mesenchymal stem cells differentiate toward adipocytes rather than osteogenic cells. RT-PCRs were completed using the bone marrow stroma cells obtained during THA from 11 patients with osteonecrosis and 9 control patients. As not all of alcoholics and steroid users develop osteonecrosis, genetic differences may relate to susceptibility to the osteonecrosis. Therefore, we determined the polymorphism of the PPARγ2 gene for 34 osteonecrosis patients and 76 controls.

Results: Among 89 cases of osteonecrosis, increased free fatty acid (above 580mg%) was the most frequent finding (40.8%), and triglyceride was the next (29.6%). Cholesterol was increased in only 9.0%. Seven of the osteonecrosis cases (63.6%) and 4 of the control cases (44.4%) expressed PPARγ2. Pro/Ala (C/G) polymorphism was found in seven (20.6%) ON cases and four control cases (5.3%), and Ala/Ala (G/G) polymorphism was found in only 1 case in the control group. The numbers of patients with elevated triglyceride among osteonecrosis were much higher (71.4%) in polymorphism (C/G) than osteonecrosis (21.5%) without polymorphism.

Discussion: In conclusion, hyperlipidemia and higher expression of the PPARγ2 were found in ON, and Pro/Ala PPARγ2 polymorphism was more common in ON.

Introduction: Resurfacing arthroplasty of the hip joint has advantages of minimal bone resection, restoration of normal anatomy, and biomechanical circumstances. This study was undertaken to analyze the clinical and radiographic results of the resurfacing arthroplasty in patients with osteonecrosis of the femoral head (ONFH).

Materials and Methods: Between September 1998 and September 2001, 40 hips in 39 patients with ONFH had a resurfacing arthroplasty with the Birmingham Hip Resurfacing (BHR) system. The mean age at the time of operation was 38.3 years. The average follow-up period was 36.8 months after operation. The patients were clinically evaluated by hip pain, Harris hip scores, range of motion, and radiographically evaluated for wear, change of cup position, loosening, and osteolysis.

Results: The preoperative Harris hip score averaged 70.4 points and the degrees of flexion and internal rotation were 94° and 8°, respectively. The average Harris hip score at the last follow-up was 95.4 points. The degrees of flexion and internal rotation at last follow-up were 120°, and 20°, respectively. No patient complained of limb length discrepancy or pain in the hip or thigh. Rehabilitation programs and return to normal activities were earlier than that of conventional total hip arthroplasty (THA). There was no osteolysis, change of cup position, loosening, or detectable wear on the latest radiographic evaluation.

Conclusions: Our experience with resurfacing arthroplasty for ONFH indicates that the overall results are superior than conventional THA with respect to pain relief, range of hip motion, earlier rehabilitation, and early return to preoperative activity. This procedure with BHR could be an alternative between joint preserving procedure and conventional THA in ONFH especially in younger patients.

Numerous studies have examined the biomechanical properties of the vertebral body following PMMA cement augmentation for the treatment of osteoporotic vertebral body fractures. To date there is no published literature reporting the effects of Vertebroplasty on internal intervertebral disc biomechanics which in turn have been shown to reflect loading patterns of the vertebral column.

To study effects of PMMA cement augmentation of vertebral body fractures on intervertebral disc biomechanics using stress prolifometry to assess differential anterior and posterior vertebral column loading.

Eight cadaveric motion segments were individually loaded on a hydraulically powered materials testing machine under 1.5kN of axial compression. Following fracture induction the lower vertebral body underwent Vertebroplasty.

Profiles of the vertically acting compressive stress were obtained by pulling a pressure sensitive transducer along the mid-sagittal diameter of the intervertebral disc. “Stress profile” measurements were obtained before fracture, following fracture, and after vertebro-plasty both in extension and flexion.

Stress profiles were integrated over area to calculate the compressive force across the disc. The compressive load acting on the neural arch was calculated by subtracting the disc force from the applied 1.5kN load.

In flexed postures posterior column loading increased from 17.1% to 42.2% following fracture (p< 0.01) and then decreased significantly from 42.2% to 23.68% following vertebroplasty (p< 0.03). There was no significant difference between pre-fracture and post-vertebroplasty status (p=0.11). In extended posture, fracture produced increased posterior column loading 72.9% vs 51.8% (p< 0.005) and following vertebroplasty there was no significant change (p=0.2).

In moderate degrees of flexion, vertebroplasty produces normalisation of load bearing through the anterior vertebral column and hence offloads the posterior elements to a significant degree. This could be postulated, to partly account for the analgesic effect seen following vertebroplasty in the clinical setting.

In 1980, Morrison and O’Brien reported their experiences with the reconstruction of an amputated thumb using a wrap-around neurovascular free flap from the great toe, but its indication has been limited distal to the metacarpophalangeal joint.

We have performed 37 wrap-around free flaps from the great toe for the reconstruction of thumbs amputated at distal or proximal to the MP joint. The amputation was distal and proximal to the MP joint in 25 and 12 cases respectively.

The opposition of reconstructed thumb to the other fingers was completely possible in all cases amputated distal to the MP joint. In the 12 cases amputated proximal to the MP joint of the thumb, opposition was completely possible in 6 cases in which the lilac bone block was fixated in the position of 30° flexion and 45° internal rotation. However, in the other six cases in the fixation of 30° flexion and 30° internal rotation, the opposition of the reconstructed thumb to the ring and little fingers was impossible in five cases and only to the little finger in one case.

We concluded that amputation proximal to the MP joint is not an absolute contraindication to the wraparound free flap procedure for thumb reconstruction. However, for a better functional outcome we recommend iliac bone block fixation in the position of 30° flexion and 45° internal rotation.

Introduction: The effect of facet tropism on the development of lumbar disc diseases has been investigated but is still controversy; moreover, there has been no study to be done on far lateral lumbar disc herniation (LDH). In the current study, the authors attempted to determine the differences of the degree of facet tropism and the degree of disc degeneration between far lateral and posterolateral LDHs. In addition, the effect of the difference of degree of facet tropism and the degree of disc degeneration on the development of far lateral LDH was investigated compared with posterolateral LDH.

Methods: 38 LDHs (far lateral, n = 19; posterolateral, n = 19) who underwent posterior open discectomy or paraspinal approach were included in this study. The mean age was 52.3 years in far lateral LDH and 45.3 years in posterolateral LDH. The degrees of facet tropism and disc degeneration were measured at herniated disc level using MRI, and compared for the two different types of LDHs. Mann-Whitney U test and Spearman test were used for analysis.

Results: There were significant statistical differences in the degree of facet tropism and the degree of disc degeneration. There was no significant correlation between the degree of facet tropism and the degree of disc degeneration in far lateral LDH.

Discussion: The current study suggests that the differences of the degree of facet tropism and the degree of disc degeneration might be considered as the key factors to determine the development of far lateral LDH compared with posterolateral LDH.