The preventive effects of bisphosphonates on articular cartilage in non-arthritic joints are unclear. This study aimed to investigate the effects of oral bisphosphonates on the rate of joint space narrowing in the non-arthritic hip. We retrospectively reviewed standing whole-leg radiographs from patients who underwent knee arthroplasties from 2012 to 2020 at our institute. Patients with previous hip surgery, Kellgren–Lawrence grade ≥ II hip osteoarthritis, hip dysplasia, or rheumatoid arthritis were excluded. The rate of hip joint space narrowing was measured in 398 patients (796 hips), and the effects of the use of bisphosphonates were examined using the multivariate regression model and the propensity score matching (1:2) model.Aims
Methods
The aim of this study was to evaluate the performance of first-generation annealed highly cross-linked polyethylene (HXLPE) in cementless total hip arthroplasty (THA). We retrospectively evaluated 29 patients (35 hips) who underwent THA between December 2000 and February 2002. The survival rate was estimated using the Kaplan-Meier method. Hip joint function was evaluated using the Japanese Orthopaedic Association (JOA) score. Two-dimensional polyethylene wear was estimated using Martell’s Hip Analysis Suite. We calculated the wear rates between years 1 and 5, 5 and 10, 10 and 15, and 15 and final follow-up.Aims
Methods
We aimed to evaluate the long-term outcome of highly cross-linked polyethylene (HXLPE) cemented acetabular components and assess whether any radiolucent lines (RLLs) which arose were progressive. We retrospectively reviewed 170 patients who underwent 187 total hip arthroplasties at two hospitals with a minimum follow-up of ten years. All interventions were performed using the same combination of HXLPE cemented acetabular components with femoral stems made of titanium alloy. Kaplan-Meier survival analysis was performed for the primary endpoint of acetabular component revision surgery for any reason and secondary endpoint of the appearance of RLLs. RLLs that had appeared once were observed over time. We statistically assessed potential relationships between RLLs and a number of factors, including the technique of femoral head autografting and the Japanese Orthopaedic Association score.Aims
Methods
This study aimed to evaluate the association between the sagittal alignment of the femoral component in total knee arthroplasty (TKA) and new Knee Society Score (2011KSS), under the hypothesis that outliers such as the excessive extended or flexed femoral component were related to worse clinical outcomes. A group of 156 knees (134 F:22 M) in 133 patients with a mean age 75.8 years (SD 6.4) who underwent TKA with the cruciate-substituting Bi-Surface Knee prosthesis were retrospectively enrolled. On lateral radiographs, γ angle (the angle between the distal femoral axis and the line perpendicular to the distal rear surface of the femoral component) was measured, and the patients were divided into four groups according to the γ angle. The 2011KSSs among groups were compared using the Kruskal-Wallis test. A secondary regression analysis was used to investigate the association between the 2011KSS and γ angle.Aims
Methods
Acquiring adaptive soft-tissue balance is one of the most important factors in total knee arthroplasty (TKA). However, there have been few reports regarding to alteration of tolerability of varus/valgus stress between before and after TKA. In particular, there is no enough data about mid-flexion stability. Based on these backgrounds, it is hypothesized that alteration of varus/valgus tolerance may influence post-operative results in TKA. The purpose of this study is an investigation of in vivo kinematic analyses of tolerability of varus/valgus stress before and after TKA, comparing to clinical results. A hundred knees of 88 consecutive patients who had knees of osteoarthritis with varus deformity were investigated in this study. All TKAs (Triathlon, Stryker) were performed using computer assisted navigation system. The kinematic parameters of the soft-tissue balance, and amount of coronal relative movement between femur and tibia were obtained by interpreting kinematics, which display graphs throughout the range of motion (ROM) in the navigation system. Femoro-tibial alignments were recorded under the stress of varus and valgus before the procedure and after implantation of all components. In each ROM (0, 30, 60, 90, 120 degrees), the data of coronal relative movement between femur and tibia (tolerability) were analyzed before and after implantation. Furthermore, correlations between tolerability of varus/valgus and clinical improvement revealed by ROM and Knee society score (KSS) were analyzed by logistic regression analysis.Introduction
Materials and Methods
The relationship between sagittal component alignment on clinical outcomes has not fully evaluated after TKA. This study evaluated the effect of sagittal alignment of the components on patient function and satisfaction as well as kinematics and kinetics. This study included 148 primary TKAs with cruciate-substituting prosthesis for primary OA. With post-operative lateral radiograph, femoral component flexion angle (γ) and tibial component posterior slope angle (90-σ) was measured. The patients was classified into multiple groups by every three degrees. Patient satisfaction in 2011KSS among groups were analyzed using one-way analysis of variance. By representing the component position which showed poor clinical outcomes, computer simulation analysis was performed, in which kinematics and kinetics in squatting activity were investigated.Introduction
Methods
Using a simple classification method, we aimed to estimate the collapse rate due to osteonecrosis of the femoral head (ONFH) in order to develop treatment guidelines for joint-preserving surgeries. We retrospectively analyzed 505 hips from 310 patients (141 men, 169 women; mean age 45.5 years Objectives
Methods
In the 1990s, a bioactive bone cement (BABC) containing apatite-wollastonite glass-ceramic (AW-GC) powder and bisphenol-a-glycidyl methacrylate resin was developed at our hospital. In 1996, we used BABC to fix the acetabular component in primary total hip arthroplasty (THA) in 20 patients as part of a clinical trial. The purpose of this study was to investigate the long-term results of primary THA using BABC. A total of 20 patients (three men and 17 women) with a mean age of 57.4 years (40 to 71), a mean body weight of 52.3 kg (39 to 64), and a mean body mass index (BMI) of 23.0 kg/m2 (19.8 to 28.6) were evaluated clinically and radiologically. Survival analyses were undertaken, and wear analyses were carried out using a computer-aided method.Aims
Patients and Methods
Unicompartmental knee arthroplasty (UKA) is one surgical option for treating symptomatic medial osteoarthritis. Clinical studies have shown the functional benefits of UKA; however, the optimal alignment of the tibial component is still debated. The purpose of this study was to evaluate the effects of tibial coronal and sagittal plane alignment in UKA on knee kinematics and cruciate ligament tension, using a musculoskeletal computer simulation. The tibial component was first aligned perpendicular to the mechanical axis of the tibia, with a 7° posterior slope (basic model). Subsequently, coronal and sagittal plane alignments were changed in a simulation programme. Kinematics and cruciate ligament tensions were simulated during weight-bearing deep knee bend and gait motions. Translation was defined as the distance between the most medial and the most lateral femoral positions throughout the cycle.Objectives
Methods
Tibial tuberosity and trochlear groove (TT-TG) distance has been investigated for the patients with primary patellofemoral subluxation/dislocation. To date, TT-TG distance after TKA has not been evaluated, and the effect of postoperative TT-TG distance on patellar tracking is unknown. The purpose of the current study was to investigate the effect of TT-TG distance and rotational position of the femoral and tibial components on patellar tilt after TKA. Consecutive 115 knees for the diagnosis of osteoarthritis were included in the current study. TKA was performed using posterior cruciate ligament sacrificed prosthesis. A total of 17 men and 96 women with an average age of 75.3 years were included at the time of the surgery. Computed tomography (CT) was taken after TKA in full extension. Postoperative TT-TG distance was measured as a reference of surgical epicondylar axis (SEA) of the femur. Patellar tilt was defined as the angle of the patellar component relative to SEA. Femoral and tibial component rotation was measured as the angle relative to SEA and tibial antero-posterior (AP) axis. Tibial AP axis was defined as the line connecting medial one-third of the tibial tuberosity and center of medial-lateral width. Pearson correlation coefficients were calculated to determine the correlations between patellar tilt and TT-TG distance and between patellar tilt and femoral and tibial component rotation.Introduction
Methods
For many years, minimally invasive joint-preserving regenerative therapy has been desired for the early stages of osteonecrosis of the femoral head (ONFH). In an animal study using adult rabbits, we reported that a single local injection of rhFGF-2-impregnated gelatin hydrogel, which has superior slow-release characteristics, suppresses the progression of femoral head necrosis. The purpose of this study was to evaluate the safety and clinical outcomes of a single local administration of rhFGF-2-impregnated gelatin hydrogel for the precollapse stage of ONFH. Patients and Methods: Ten patients with femoral heads up to precollapse stage 2 underwent a single local administration of 800-µg rhFGF-2-impregnated gelatin hydrogel and were followed up for two years. The eligibility criteria were age between 20 and 80 years and presence of ONFH at precollapse stage 1 or 2 according to the classification system for ONFH developed by the Japanese Investigation Committee of Health and Welfare. Primary outcomes included adverse events and complications. Secondary outcomes included changes in Harris Hip Scores (HHS), visual analog scale pain scores (VAS), the University of California, Los Angeles (UCLA) activity rating scores, radiological changes as determined via radiographs, computed tomography (CT) scans, and magnetic resonance imaging (MRI) of the hip joint. Results: We included five men (five hips) and five women (five hips), with a mean age of 39.8 years (range: 29–53 years) at the time of surgery. Eight patients had bilateral ONFH, three had already undergone THA on the contralateral side. Eight patients were receiving treatment with corticosteroid therapy, and two patients overused alcohol. Stage 1 and 2 disease was present in one and nine patients, respectively. One patient each had type A, type B, and type C1 disease, whereas seven patients had a type C2 lesion. All Adverse events were recovered without problem. The surgery was performed with a minimally invasive technique based core decompression (1 cm of skin incision), and walking was allowed from the day after surgery. Mean clinical scores improved significantly after three year compared with before surgery (before vs. after: VAS for pain, 21.2 vs. 5.3 mm; UCLA activity score 5.5 vs. 6.6; HHS, 81.0 vs. 98.4 points, respectively). There was only one case of femoral head collapse, and it had the greatest necrosis volume fraction and was considered to be in the early collapse stage at the time of operation. The other nine cases did not involve ONFH stage progression, and collapse was prevented. CT images and recent MRI postoperatively confirmed bone regeneration and reduction of the necrotic area. Conclusion: Clinical application of rhFGF-2-impregnated gelatin hydrogel for patients with precollapse stage of ONFH was feasible and safe. Our research is ongoing, further phase II multiple center study has been started in January 2016.Introduction
All animal experiments were performed on IACUC approved protocols. USA300LAC (MRSA) and RP62A(INTRODUCTION
METHODS
Recently, tibial insert design of cruciate-substituting (CS) polyethylene insert is employed and widely used. However, in vivo kinematics of using CS polyethylene insert is still unclear. In this study, it is hypothesized that CS polyethylene insert leads to stability of femoro-tibial joint as well as posterior-stabilized (PS) polyethylene insert, even if PCL is sacrificed after TKA. The purpose of this study is an investigation of in vivo kinematics of femoro-tibial joint with use of CS polyethylene insert before and after PCL resction using computer assisted navigation system and tensor device intra-operatively in TKA. Sixty-one consecutive patients who had knees of osteoarthritis with varus deformity were investigated in this study. All TKAs (Triathlon, Stryker) were performed using computer assisted navigation system. During surgery, using a tensor device, after bony cut of femur and tibia, joint gaps were assessed in 0 and 90 degrees in flexion. Then, CS polyethylene tibial trial insert were inserted after trial implantation of femoral and tibial components, before and after resection of PCL, respectively. The kinematic parameters of the soft-tissue balance, and amount of coronal and sagittal relative movement between femur and tibia were obtained by interpreting kinematics, which display tables throughout the range of motion (ROM) in the navigation system. In each ROM (30, 45, 60, 90, max degrees), the data were analyzed with a ANOVA test, and mean values were compared by the multiple comparison test (Turkey HSD test) (p< 0.05).Introduction
Materials and Methods
The long-term wear performance of highly cross-linked polyethylene (HXLPE) in cemented total hip arthroplasty (THA) has rarely been reported. Here we report a prospective randomized comparative analysis of radiographic wear after a minimum follow-up of 10 years in cemented THAs with either HXLPE or conventional polyethylene (CPE), and assess its clinical relevance. From 1999 to 2001, we conducted 94 primary cemented THAs with a 22.225-mm head at our hospital as part of a prospective randomized trial. All surgeries were performed using a direct lateral approach with a trochanteric osteotomy (Dall's approach). The patients were divided into 4 groups. Twenty-six hips in group A were implanted with CPE sockets against zirconia heads and Charnley-type stems. HXLPE sockets (Aeonian, Kyocera Medical Corp) were implanted in all hips in the other 3 groups. Twenty-five hips in group B were implanted with zirconia heads and KC stems (Kyocera Medical Corp), 23 hips in group C with zirconia heads and distal cylindrical stems, and 20 hips in group D with stainless steel heads and C-stem (DePuy Inc). The sockets were highly cross-linked by gamma irradiation at a dose of 35 kGy, heat annealed at 110ºC, and sterilized with 25 kGy of gamma irradiation in nitrogen. For radiographic evaluation, anteroposterior radiograms were taken for each patient annually, and every two years postoperatively for wear analyses. Two-dimensional head penetration was measured on each postoperative radiogram using a computer-aided technique.Introduction
Patients and Methods
Little biomechanical information is available about kinematically aligned (KA) total knee arthroplasty (TKA). The purpose of this study was to simulate the kinematics and kinetics after KA TKA and mechanically aligned (MA) TKA with four different limb alignments. Bone models were constructed from one volunteer (normal) and three patients with three different knee deformities (slight, moderate and severe varus). A dynamic musculoskeletal modelling system was used to analyse the kinematics and the tibiofemoral contact force. The contact stress on the tibial insert, and the stress to the resection surface and medial tibial cortex were examined by using finite element analysis.Objectives
Materials and Methods
Total hip arthroplasty (THA) for a highly dislocated hip can be problematic and technically challenging. Our previous study on cemented THA with subtrochanteric femoral shortening osteotomy revealed a high incidence (20%) of non-union. Therefore, in 2008, we introduced reverse hybrid THA using S-ROM stem for the treatment of a highly dislocated hip. The purpose of this study was to assess the short-term clinical outcomes of this new method. Between 2008 and 2014, 13 consecutive reverse hybrid THAs were performed on nine female patients with highly dislocated hips. The average age at the time of operation was 66 years (range, 55–85 years). The acetabular component was fixed in the true acetabulum with bone cement. Transverse osteotomy was performed below the lesser trochanter to shorten the femur and to prevent over-lengthening. The proximal sleeve of the S-ROM stem was then fixed within the proximal fragment, and the distal fin provided rotational stability of the distal fragment. Thus, the two fragments were fixed to each other with the S-ROM stem, and the resected segment was longitudinally cut for grafting at the junction. The postoperative follow-up period was an average of 4 years (range, 1–7 years), and no patients were lost. Preoperative and final Japanese Orthopaedic Association (JOA) hip score, operation time, bleeding amount, intraoperative and postoperative complications, bone healing at the osteotomy site, implant loosening, and revision surgery were retrospectively investigated.Introduction
Patients and methods
Composite screws of uncalcined and unsintered hydroxyapatite (HA) particles and poly-l-lactide (PLLA) were developed as completely absorbable bone fixation devices. So far the durability of HA-PLLA composite screws is unclear when used for the fixation of acetabular bone graft in total hip arthroplasty under full-weight conditions. We have used this type of screw for the fixation of acetabular bone graft in cemented or reverse-hybrid total hip arthroplasty since 2003. Hence, we conducted a follow-up study to assess the safety and efficacy of these screws when used for cemented socket fixation. During 2003–2009, HA-PLLA composite screws were used for fixation of acetabular bone graft in cemented or reverse-hybrid primary THA in 106 patients (114 cases). All the THAs were performed through direct lateral approaches, and postoperative gait exercise with full weight bearing usually started two days after surgery. One patient died of an unrelated disease and seven patients were lost to follow-up within 5 years. Finally, 98 patients (106 cases) were followed up for over 5 years and were reviewed retrospectively (follow-up rate, 93%). Radiographic loosening of the acetabular component was assessed according to the criteria of Hodgkinson et al., and the radiolucent line around the socket was evaluated in all zones, as described by DeLee and Charnley.Background
Methods
Total elbow arthroplasty (TEA) has become an established procedure in the treatment of patients with rheumatoid arthritis (RA). However, there is little information on whether limited extension of the elbow affects clinical outcome scores after TEA and what causes the limited extension. We retrospectively analyzed fifty-four cases of primary TEA in patients with RA. There were seven men and thirty-nine women with a mean age of 63.6 years (range, thirty to eighty years). Thirty-seven of Coonrad-Morrey and seventeen of Discovery prostheses were used. The mean length of follow-up was 7.1 ± 4.0 years (range 2.0–14.6 years). Mayo Elbow Performing Score (MEPS) and radiological measurements were recorded. Anteroposterior and lateral radiographs were assessed before and after the operation and at the latest follow-up. Widening of the joint space was calculated by subtracting the length measured on the postoperative radiograph from that on the preoperative radiograph.Background
Methods
Genu recurvatum deformities are unusual before total knee arthroplasty (TKA), occurring in less than 1% of patients. The purpose of this study is to evaluate the clinical and radiographic results of primary TKA in patients that had recurvatum deformities before surgery. The inclusion criteria was to have recurvatum deformity over 10 degrees on lateral standing X-ray view. We retrospectively reviewed 22 knees with pre-operative recurvatum deformities, and the incident was 1.0% of all TKAs at our hospital. The etiology of the arthritis was osteoarthritis in 21 knees, of which 3 knees were neuropathic disease, and rheumatoid arthritis in 1 knee. There were 6 men and 16 women, and the average age was 73.3 years (range, 53 to 83 years) at the time of operation. The average follow-up period was 15 months (range, 3 to 81 months). We performed to use medial parapatellar approach and bone cutting was done by measured resection technique. The surgical knacks were resection of less distal femur and proximal tibia bone to make extension gap tightly, additionally decrease the tibial posterior slope. Posterior-stabilizer (PS) implants (NexGen LPS: Zimmer, Bisurface KU4+: JMM) were used in 20 knees and constrained implants (NexGen RH knee: Zimmer, Endo-Model Hinge Knee: Link) were in 2 knees with neuropathic joints.Introduction
Patients and Methods
Postoperative peritrochanteric pain, which can be caused by non-union of the greater trochanter in those who have undergone total hip arthroplasty (THA) with trochanteric osteotomy, affects patient satisfaction. We reviewed 89 consecutive cases of primary THA performed with a mini-trochanteric direct lateral approach (Wafer approach), during which the anteroinferior trochanteric fragment (2 cm × 1 cm) attached to the anterior one-third or one-fourth of the gluteus medius muscle insertion and the entire insertion of the gluteus minimus muscle were osteotomized and detached using a curved chisel for exposure, while the origin of the vastus lateralis muscle remained intact. After completion of implantation, the detached fragment was fixed in the original position using 2 parallel braided sutures. If returning the trochanteric fragment to its original position was difficult, the tightened posterior tendinous portion of the gluteus minimus muscle was released to reduce the fragment easily and was then fixed. The surgeries, which included 19 cemented, 7 cementless, and 63 hybrid THAs, were performed between January 2012 and August 2013, and the patients [13 men, 76 women; average age, 65.6 years (38–86 years)] were followed for 6 months. The original diagnosis included primary osteoarthritis in 7 cases, osteoarthritis secondary to dysplasia in 75 cases, and avascular necrosis of the femoral head in 7 cases. X-ray examination including anteroposterior (AP) and lateral hip views was performed at 1, 3, and 6 months postoperatively, and a displacement of > 5 mm of the osteotomized fragment in either the AP or lateral view was considered fragment migration. The Japanese Orthopaedic Association (JOA) pain score was also recorded at 3 and 6 months postoperatively. We examined the possible factors affecting trochanteric migration and JOA pain score, including age, sex, THA type, leg lengthening, Crowe classification, and suture type. We also examined the correlation between trochanteric migration and JOA pain score. There were no peri- or post-operative complications including infection, deep venous thrombosis, dislocation, or periprosthetic fracture. No revision or radiographic loosening occurred in the follow-up period. Average leg lengthening was 9.8 mm (−4–21 mm), measured on the AP X-ray of the hip as the vertical interval between the pre- and postoperative positions of the lesser trochanter. There were 35 cases (39.3%) of trochanteric migration at postoperative 3 months. The Chi-square test and logistic regression analysis indicated that age, sex, Crowe classification, leg lengthening, and suture type did not affect trochanteric migration or JOA pain score. On the other hand, THA type did not affect trochanteric migration but did affect JOA pain score at postoperative 3 months. Patients who underwent cementless THA had worse JOA pain scores than the other patients. There was no correlation between trochanteric migration and JOA pain scores. The results indicated that trochanteric fragment migration often occurred in this series using the Wafer approach. Although the pain score is affected by many factors including thigh pain, hip abductor weakness, and wound irritation in the short term, it did not correlate with the trochanteric nonunion rate of this approach.
Ultra-high molecular weight polyethylene (UHMWPE) tape, which comprised threads of UHMWPE fibers with the thickness less than 0.5 mm, was developed as a flexible fixation device. We describe new techniques using UHMWPE tape for the reattachment of the osteotomised fragment and the repair of intraoperative calcar fractures in total hip arthroplasty (THA). We reviewed the medical records and radiographs of the studied subjects after approval of this study by the institutional review board committee. Experiment 1: Between October 2011 and May 2012, 60 consecutive primary THAs were performed with the mini-trochanteric approach, which involved reattaching the osteotomised fragment using UHMWPE tape (Nesplon; Alfresa Pharma, Osaka, Japan). [Fig.1] By splitting the anterior one-fourth of the gluteus medius, the minitrochanteric osteotomy, a half-ellipsoid body about 15 mm long, 10 mm wide, and 5 mm deep, is performed using a curved chisel. After implanting of the prosthesis, the osteotomised fragment is reattached by using two 3-mm wide Nesplon tapes. Using 2.4 mm Kirshner wire, two sets of drill holes are created below the trochanteric bed of the femur. Nesplon tapes are passed through each drill hole and penetrated over the trochanteric fragment. Nesplon tape is tied using a double-loop sliding knot in conjunction with a special tightening gun tensioner up to 20 kgf. [Fig.2] The radiographic results were retrospectively analyzed to determine the incidence of nonunion and complications related to trochanteric site. Hip functional results were rated according to the Japanese Orthopedic Association (JOA) hip score. Experiment 2: Between July 2011 and May 2012, 5-mm wide Nesplon tapes were used for restoration of intraoperative femoral fractures in 4 primary THAs. For the repair of intraoperative proximal femoral fractures, 5-mm wide Nesplon tape is tightened with cerclage wiring technique using the gun tensioner up to 30 kgf. [Fig.3] The postoperative radiographic changes were analyzed.Introduction
Patients & Methods
Malrotation of the tibial component would lead to various complications after total knee arthroplasty (TKA) such as improper joint kinematics, patellofemoral instability, or excessive wear of polyethylene. However, despite reports of internal rotation of the tibial component being associated with more severe pain or stiffness than external rotation, the biomechanical reasons remain largely unknown. In this study, we used a musculoskeletal computer model to simulate a squat (0°–130°–0° flexion) and analyzed the effects of malrotated tibial component on lateral and medial collateral ligament (LCL and MCL) tensions, tibiofemoral and patellofemoral contact stresses, during the weight-bearing deep knee flexion. A musculoskeletal model, replicating the dynamic quadriceps-driven weight-bearing knee flexion in previous cadaver studies, was simulated with a posterior cruciate-retaining TKA. The model included tibiofemoral and patellofemoral contact, passive soft tissue and active muscle elements. The soft tissues were modeled as nonlinear springs using previously reported stiffness parameters, and the bony attachments were also scaled to some cadaver reports. The neutral rotational alignment of the femoral and tibial components was aligned according to the femoral epicondylar axis and the tibial anteroposterior axis, respectively. Knee kinematics and ligament tensions were computed during a squat for malrotated conditions of the tibial component. The tibial rotational alignments were changed from 15° external rotation to 15° internal rotation in 5° increments. The MCL and LCL tensions, the tibiofemoral and patellofemoral contact stresses were compared among the knees with different rotational alignment.Introduction
Materials and Methods
Kinematically aligned total knee arthroplasty (TKA) is of increasing interest because this method may improve patient satisfaction. However, the biomechanics of kinematically aligned TKA remain largely unknown. Therefore, we analyzed whether the kinematic alignment method cause to increase the contact force on patellofemoral and tibiofemoral joints. A musculoskeletal computer simulation was used to determine the effects of kinematically or mechanically aligned TKA. Patellofemoral and tibiofemoral contact forces were examined for a mechanically aligned model and a kinematically aligned model using finite element analysis.Objective
Methods
In order to reduce polyethylene wear and incidence of osteolysis, and improve the long-term durability of total hip arthroplasty (THA), highly cross-linked polyethylene was introduced for clinical use in substitution for conventional polyethylene. We performed 35 cementless THAs between December 2000 and February 2002, and cross-linked polyethylene was used in these surgeries. The purpose of this study is to research linear wear rate of these hips, and to find the risk factor for high wear rate. 32 hips (26 patients) among the 35 could be evaluated at more than 10 years postoperatively. One hip required reoperations due to infection at 8 years postoperatively, and two were lost to followup in less than 10 years. There were 2 males and 24 females, and the observation period was 11.4 years in average (range 10?13 years). The age at the time of operation was 49.4 years in average (range 24?67 years), and body mass index was 22.4 in average (15?34). We used AHFIX total hip prostheses (KYOCERA Medical Corporation) for both acetabular and femoral replacement, and 22 mm Zirconia head was used in all cases. The median cup diameter was 46 mm (range 42?50). Osteolysis and loosening of the implant was evaluated on the anteroposterior radiograph of the hip. Using software for wear measurement (Hip Analysis Suite), linear wear rate and cup inclination angle were measured. Correlation between linear wear rate and age, BMI, cup inclination angle, and cup diameter was investigated using correlation coefficient.Introduction
Patients and Methods
Using the tibial extramedullary guide needs meticulous attention to accurately align the tray in total knee arthroplasty (TKA). We previously reported the risk for varus tray alignment if the anteroposterior (AP) axis of the ankle was used for the rotational direction of the guide. The purpose of our study was to determine whether aligning the rotational direction of the guide to the AP axis of the proximal tibia reduced the incidence of varus tray alignment when compared to aligning the rotational direction of the guide to the AP axis of the ankle.Introduction
Materials and Methods
Previously more femoral rollback has been reported in posterior-stabilized implants, but so far the kinematic change after post-cam engagement has been still unknown. The tri-condylar implants were developed to fit a life style requiring frequent deep flexion activities, which have the ball and socket third condyle as post-cam mechanism. The purpose of the current study was to examine the kinematic effects of the ball and socket third condyle during deep knee flexion. The tri-condylar implant analyzed in the current study is the Bi-Surface Knee System developed by Kyocera Medical (Osaka, Japan). Seventeen knees implanted with a tri-condylar implant were analyzed using 3D to 2D registration approach. Each patient was asked to perform a weight-bearing deep knee bend from full extension to maximum flexion under fluoroscopic surveillance. During this activity, individual fluoroscopic video frames were digitized at 10°increments of knee flexion. A distance of less than 1 mm initially was considered to signify the ball and socket contact. The translation rate as well as the amount of translation of medial and lateral AP contact points and the axial rotation was compared before and after the ball and socket joint contact. The average angle of ball and socket joint contact were 64.7° (SD = 8.7), in which no separation was observed after initial contact. The medial contact position stayed from full extension to ball and socket joint contact and then moved posteriorly with knee flexion. The lateral contact position showed posterior translation from full extension to ball and socket joint contact, and then greater posterior translation after contact (Figure 1). Translation and translation rate of contact positions were significantly greater at both condyles after ball and socket joint contact. The femoral component rotated externally from full extension to ball and socket joint contact, and then remained after ball and socket joint contact (Figure 2). There was no statistical significance in the angular rotation between ball and socket joint contact and maximum flexion. Translation of angular rotation was significantly greater before ball and socket joint contact, however, there was no significance in translation rate before and after ball and socket joint contact. The ball and socket joint was proved to induce posterior rollback intensively. In terms of axial rotation, the ball and socket joint did not induce reverse rotation, but had slightly negative effects after contact. The ball and socket provided enough functions as a posterior stabilizing post-cam mechanism and did not prevent axial rotation.
Total knee arthroplasty (TKA) is one of the most successful surgeries with respect to relieving pain and restoring function of the knee. However, some studies have reported that patients are not always satisfied with their results after TKA. The aim of this study was to determine which factors contribute to patient's satisfaction after TKA. We evaluated 69 patients who had undergone 76 primary TKAs between March 2012 and June 2013, and assessed patient- and physician- reported scores using the 2011 Knee Society Scoring System and clinical variables before and after TKAs. We determined the correlation between patient satisfaction and clinical variables.Purpose
Methods
In articular cartilage defects, chemokines are upregulated and potentially induce the migration of bone marrow cells to accelerate the healing processes. The treatment of damaged articular cartilages is one of the most challenging issues in sports medicine and in aging societies. In the microfracture technique for the treatment of articular cartilage defects, bone marrow cells are assumed to migrate from the bone marrow. Bone marrow cells are well-known for playing crucial roles in the healing processes, but how they can migrate from underlying bone marrow remains to be investigated. We have previously shown that SDF-1, one of chemokines, play crucial roles in the recruitment of mesenchymal stem cells in bone healing processes, and the induction of SDF-1 can induce a successful bone repair. If the migration can be stimulated by any means in the cartilage defects, a better result can be expected. The aim of this study was to elucidate the mechanisms of the migration of bone marrow cells and which factors contribute to the processes.Summary Statement
Introduction
MCP-1/ CCR2 axis at the early phase plays a pivotal role in the fracture healing. Inflammation plays a pivotal role in fracture healing. Among them, chemokines play key roles in inflammation. Monocyte chemotactic protein-1 (MCP-1), via its receptor C-C chemokine receptor 2 (CCR2), acts as a potent chemoattractant for various cells to promote migration from circulation to inflammation site. Thus, the importance of MCP-1/CCR2 axis in fracture healing has been suggested. However, the involvement of MCP-1/CCR2 axis tofracture site is not fully elucidated. PCR Array: The expression of MCP-1 and MCP-3 had increased on day 2 than 0 or 7 in the rib fracture healing. Immunohistochemistry Staining: To verify the localization of MCP-1 expression, we examined the Wild type (WT)-mouse rib fracture healing. We observed high expression of MCP-1 and MCP-3 at the periosteum and the endosteum on post-fracture day 3. Summary Statement
Results
Dual SC Screw (DSCS) is a novel fixation device for the femoral neck fracture. DSCS is comprised of screw and barrel allowing sliding of the screw and preventing protrusion of the screw end. Two types of the barrels are available, threaded barrel (TB) and plate barrel (PB). Ordinarily, both barrels are implanted. Concept of the design is that the PB contributes stability to the screw against the varus force of the femoral head while the additional screw with TB prevents rotational deformity. The aim of this study was to represent clinical results after DSCS operation in patients with femoral neck fracture. Fifty-one patients with femoral neck fractures treated using DSCS and at least 3 months follow up are included and their clinical was evaluated.Aims
Method
Knee contact force during activities after total knee arthroplasty (TKA) is very important, since it directly affects component wear and implant loosening. While several computational models have predicted knee contact force, the reports vary widely based on the type of modeling approach and the assumptions made in the model. The knee is a complex joint, with three compartments of which stability is governed primarily by soft tissues. Multiple muscles control knee motion with antagonistic co-contraction and redundant actions, which adds to the difficulty of accurate dynamic modeling. For accurate clinically relevant predictions a subject-specific approach is necessary to account for inter-patient variability. Data were collected from 3 patients who received custom TKA tibial prostheses instrumented with force transducers and a telemetry system. Knee contact forces were measured during squatting, which was performed up to a knee flexion angle that was possible without discomfort (range, 80–120°). Skin marker-based video motion analysis was used to record knee kinematics. Preoperative CT scans were reconstructed to extract tibiofemoral bone geometry using MIMICS (Materialise, Belgium). Subject-specific musculoskeletal models of dynamic squatting were generated in a commercial software program (LifeMOD, LifeModeler, USA). Contact was modeled between tibiofemoral and patellofemoral articular surfaces and between the quadriceps and trochlear groove to simulate tendon wrapping. Knee ligaments were modeled with nonlinear springs: the attachments of these ligaments were adjusted to subject-specific anatomic landmarks and material properties were assigned from published reports.INTRODUCTION
METHODS
In posterior stabilised total knee replacement
(TKR) a larger femoral component is sometimes selected to manage the
increased flexion gap caused by resection of the posterior cruciate
ligament. However, concerns remain regarding the adverse effect
of the increased anteroposterior dimensions of the femoral component
on the patellofemoral (PF) joint. Meanwhile, the gender-specific
femoral component has a narrower and thinner anterior flange and
is expected to reduce the PF contact force. PF contact forces were
measured at 90°, 120°, 130° and 140° of flexion using the NexGen
Legacy Posterior Stabilized (LPS)-Flex Fixed Bearing Knee system
using Standard, Upsized and Gender femoral components during TKR.
Increasing the size of the femoral component significantly increased
mean PF forces at 120°, 130° and 140° of flexion (p = 0.005, p <
0.001 and p <
0.001, respectively). No difference was found in
contact force between the Gender and the Standard components. Among
the patients who had overhang of the Standard component, mean contact
forces with the Gender component were slightly lower than those
of the Standard component, but no statistical difference was found
at 90°, 120°, 130° or 140° of flexion (p = 0.689, 0.615, 0.253 and
0.248, respectively). Upsized femoral components would increase PF forces in deep knee
flexion. Gender-specific implants would not reduce PF forces.
Total knee arthroplasty (TKA) has become one of the most successful procedures in orthopedics, and its survival rates are reportedly greater than 90% after 15 years. Malpositioning of the component, however, can lead to various failures, such as aseptic loosening, instability, polyethylene wear, and patellar dislocation. Navigation systems for TKA have been developed to improve postoperative alignment. Many clinical and experimental studies of these navigation systems have shown that the accuracy of implanted components has improved. We have compared the alignment of 150 total knee replacements implanted using a computed tomography-based navigation system and using the conventional alignment guide system when performed by a single surgeon. The knees were evaluated using full-length weight-bearing anteroposterior radiographs and computed tomography scans. For the navigated group, the average hip-knee-ankle angle, the femoral component angle to the femoral mechanical axis, and the tibial component angle to the mechanical tibial axis were 179.5, 89.4 and 89.7 degrees. The rotational femoral and tibial component angles to the planning axis were 0.6 and 0.3 degrees. The ideal angles of all alignments in the navigated group were obtained at significantly higher rates than in the conventional group. Our results demonstrated significant improvements in component positioning with CT-based navigation system, especially with respect to rotational alignment. Recently, we established a new method for 3D reconstruction from postoperative CT images in order to accurately measure the alignment of the component relative to any designed plane. The results showed that the discrepancy between the two-dimensional and three-dimensional evaluations was 0.3 ± 1.8 (−2.7–3.4) degrees. The coronal femoral angle for 36 knees (97.3%) and the coronal tibial angle for all the 37 knees (100%) were obtained within 3 degrees from the optimal angle. It is possible to measure the postoperative alignment for TKA more accurately on the basis of the defining plane. Three-dimensional analysis is necessary to evaluate the accuracy of the navigation system. We conclude that navigation system is a very useful tool for achieving proper postoperative alignment. Controversy still exists regarding accuracy in rotational alignment with image-free navigation, but our results showed that CT-based system significantly improved accuracy of rotational alignment. We should keep using and improving the systems to establish more simplified and accurate systems.
We investigated whether the extension gap in total knee replacement (TKR) would be changed when the femoral component was inserted. The extension gap was measured with and without the femoral component in place in 80 patients with varus osteoarthritis undergoing posterior-stabilised TKR. The effect of a post-operative increase in the size of the femoral posterior condyles was also evaluated. The results showed that placement of the femoral component significantly reduced the medial and lateral extension gaps by means of 1.0 mm and 0.9 mm, respectively (p <
0.0001). The extension gap was reduced when a larger femoral component was selected relative to the thickness of the resected posterior condyle. When the post-operative posterior lateral condyle was larger than that pre-operatively, 17 of 41 knees (41%) showed a decrease in the extension gap of >
2.0 mm. When a specially made femoral trial component with a posterior condyle enlarged by 4 mm was tested, the medial and lateral extension gaps decreased further by means of 2.1 mm and 2.8 mm, respectively. If the thickness of the posterior condyle is expected to be larger than that pre-operatively, it should be recognised that the extension gap is likely to be altered. This should be taken into consideration when preparing the extension gap.
Mechanical failure because of wear or fracture of the polyethylene tibial post in posteriorly-stabilised total knee replacements has been extensively described. In this study of 12 patients with a clinically and radiologically successful NexGen LPS posteriorly-stabilised prosthesis impingement of the anterior tibial post was evaluated in vivo in three dimensions during gait using radiologically-based image-matching techniques. Impingement was observed in all images of the patients during the stance phase, although the NexGen LPS was designed to accommodate 14° of hyperextension of the component before impingement occurred. Impingement arises as a result of posterior translation of the femur during the stance phase. Further attention must therefore be given to the configuration of the anterior portion of the femoral component and the polyethylene post when designing posteriorly-stabilised total knee replacements.
We compared the alignment of 39 total knee replacements implanted using the conventional alignment guide system with 37 implanted using a CT-based navigation system, performed by a single surgeon. The knees were evaluated using full-length weight-bearing anteroposterior radiographs, lateral radiographs and CT scans. The mean hip-knee-ankle angle, coronal femoral component angle and coronal tibial component angle were 181.8° (174.2° to 188.3°), 88.5° (84.0° to 91.8°) and 89.7° (86.3° to 95.1°), respectively for the conventional group and 180.8° (178.2° to 185.1°), 89.3° (85.8° to 92.0°) and 89.9° (88.0° to 93.0°), respectively for the navigated group. The mean sagittal femoral component angle was 85.5° (80.6° to 92.8°) for the conventional group and 89.6° (85.5° to 94.0°) for the navigated group. The mean rotational femoral and tibial component angles were −0.7° (−8.8° to 9.8°) and −3.3° (−16.8° to 5.8°) for the conventional group and −0.6° (−3.5° to 3.0°) and 0.3° (−5.3° to 7.7°) for the navigated group. The ideal angles of all alignments in the navigated group were obtained at significantly higher rates than in the conventional group. Our results demonstrated significant improvements in component positioning with a CT-based navigation system, especially with respect to rotational alignment.
It is recommended in the TKA operation to balance the tension of soft tissues to make the rectangular gap in both flexion and extension because significant imbalance may result in eccentric stress on the polyethylene insert. However, no intensive research has been done on the medial and lateral laxity of the normal knee X-ray of 50 normal knees were taken under the varus or valgus stress in both extension and flexion at 80 degrees. The angle of lines on the femoral condyles and tibia plateau was measured. The same methods were also done for the 20 osteoarthritis knees. In extension of the normal knees, the mean angle was 5.06 degrees in varus stress and was 2.46 degrees in valgus stress. In flexion of the normal knees, the mean angle was 5.04 degrees in varus stress and was 1.82 degrees in valgus stress. Therefore, the lateral laxity was significantly larger than the medial laxity in both extension and flexion (p<
0.0001). The lateral laxity was significantly larger also in osteoarthritis knees (p<
0.0001). There are some arguments about the priority to make the perfect rectangular gaps. The methods to measure the tension of soft tissues during the operation are not accurate and does not always reflect the post-operative tensions. Furthermore, the tension during the operation may be different from dynamic phase such as walking and standing. The present study showed that the mediolateral laxity was asymmetrical in the normal knees. This imbalance may be necessary for the medial pivot movement of the normal knee. These results suggest that a slight lateral laxity is acceptable during TKA operation and may be beneficial to achieve the normal kinematics especially for the cruciate retaining prosthesis.
Minimally invasive surgery (MIS) for unicompartmental knee arthroplasty (UKA) has become increasingly popular. However, wound problems may be encountered with longitudinal skin incisions. This probably occurs because the skin is under excessively high tension during MIS. We have been using transverse incisions for MIS-UKA. We describe the surgical technique and an experimental study for assessing blood flow in the skin around the knee. A 5–7 cm transverse skin incision was made from the medial edge of the patella at the level of 1–2 cm proximal to the joint line. The capsule was incised along the medial parapatellar up to the proximal two-thirds of the patella, and a few cm were also cut along the distal end of the vastus medialis. Because skin on the anterior aspect of the knee is more flexible in the longitudinal direction, exposure is easy even with a small incision.
Blood flow was markedly increased due to congestion when the depressor was placed longitudinally. On the contrary, changes in blood flow were significantly lower when the depressor was placed transversely. Transverse incision can lead to better exposure and permit an smaller incision. Moreover, transverse incisions are less invasive to the skin’s circulation and leave less distinctive scars than longitudinal incisions.
Kinematics of mobile bearing TKA has been evaluated by fluoroscopic studies. However, these studies focused on the relative motion between the femoral component and the tibial tray. The purpose of this study was to investigate the kinematics of the polyethylene insert in mobile bearing TKA under dynamic conditions using a custom-made 6-DOF kneesimulator. The mobile bearing TKA used in this study had a ågstopåh on the tibial tray, allowing rotation and translation. The implants were mounted on the knee simulator. Vertical load and 5-DOF motions were regulated according to the kinematic data from the literature. The knee simulating test was conducted under three different conditions including a static condition and dynamic conditions of 0.5 Hz and 1.0 Hz. Four metal balls mounted on the insert were observed with two cameras, and position of the insert was calculated. Contact pressure on the insert was also measured using a tactile sensor. Under the static condition, the femoral component kept almostfull contact with the insert. However, the insert shifted posteriorly with impingement to the stop under the 0.5 Hz condition. Under the 1.0 Hzcondition, antero-posterior translation of the insert was larger with impingement to the stop in both directions and contact pressure was greater. To our knowledge, no study on the motion of the insert of the mobile bearing TKA has been reported. In the present study, the insert showed different motion and contact stress according to the given condition, in spite of the same relative motion between the femoral component and the tibial tray.
All polyethylene tibial components (APT) for total knee joint replacement have been recently reintroduced due to their past success and cost savings with respect to knee designs with a metal backed tibial tray (MBT). However, isolated cases of collapse of the medial bone in APT designs have been observed by the authors prompting this investigation. The objective of this study was to investigate the stress/strain distribution within the cancellous bone for the APT and MBT systems, particularly looking at the effects of coverage of the tray over the proximal tibia in each design. A three-dimensional finite element model of the proximal tibia implanted with a tibia tray was generated. An elliptical cylindrical tibia tray with a peg was modeled as being perfectly bonded to a PMMA layer on the superior surface of the cancellous and cortical bone. Gap size between the edge of the tray and outer of the cancellous bone, was introduced in the medial direction. Load was applied on the superior surface of the tibial insert in the medial side. Two lift-off loading cases were used, a low load of 800N (1 body-weight) and a high load of 3200N (4 x BW), both on the medial side. Permanent plastic deformation and collapse was allowed only in the cancellous bone, while all other materials were modeled elastically. Under low load conditions within the elastic limit, introducing a gap between the tray and the cortical bone produced a stress/strain intensity in the cancellous bone beneath the edge of the tray. The strain in the cancellous bone within the APT design was generally 3 times greater than the MBT design, however, peak strain values were similar at the edge of the tray. Whilst the strain increased with the introduction of a gap the resulting strain was not sensitive to the gap size for both designs. Under high load conditions, permanent plastic deformation and bone collapse were observed in the cancellous bone at the edge of the tibial tray in both designs where a gap was introduced. The maximum strain in the cancellous bone was found to be more sensitive to the gap size for the APT design than the MBT design. This can be contributed to the difference in the load transfer through the cancellous bone in the two designs. The MBT design with the more rigid tibial tray transfered higher load through the outer cortical bone than the APT design. The less rigid APT design resulted in progressive collapse of the cancellous bone beneath the tray. Particularly significant was the volume of highly stressed cancellous bone which was 4 times greater in the APT design compared to the MBT design. The results suggest that coverage may be a more important parameter for the APT design than the MBT design. The APT design may, therefore, be more suited to patients with better bone quality.
We have previously developed a radiographic technique, the oblique posterior condylar view, for assessment of the posterior aspect of the femoral condyles after total knee arthroplasty. The purpose of this study was to confirm the validity of this radiographic view based upon intra-operative findings at revision total knee arthroplasty. Lateral and oblique posterior condylar views were performed for 11 knees prior to revision total knee arthroplasty, and radiolucent lines or osteolysis of the posterior aspect of the femoral condyles were identified. These findings were compared with the intra-operative appearance of the posterior aspects of the femoral condyles. Statistical analysis showed that sensitivity and efficacy were significantly better for the oblique posterior condylar than the lateral view. This method can, therefore, be considered as suitable for routine follow-up radiographs of the femoral component and in the pre-operative planning of revision surgery.
We measured the contact areas and contact stresses at the post-cam mechanism of a posterior-stabilised total knee arthroplasty when a posterior force of 500 N was applied to the Kirschner Performance, Scorpio Superflex, NexGen LPS Flex Fixed, and NexGen LPS Flex Mobile knee systems. Measurements were made at 90°, 120°, and 150° of flexion both in neutral rotation and 10° of internal rotation of the tibial component. Peak contact stresses at 90°, 120°, and 150° were 24.0, 33.9, and 28.8 MPa, respectively, for the Kirschner; 26.0, 32.4, and 22.1 MPa, respectively, for the Scorpio; and 34.1, 31.5, and 32.5 MPa, respectively, for the NexGen LPS Flex Fixed. With an internally rotated tibia, the contact stress increased significantly with all the fixed-bearing arthroplasties but not with the NexGen LPS Flex Mobile arthroplasty. The post-cam design should be modified in order to provide a larger contact area whilst avoiding any impingement and edge loading.
We evaluated the geometry of the resected femoral surface according to the theory for total knee arthroplasty (TKA) using three-dimensional computed tomography (3D CT). The 3D CT scans were performed in 44 knees indicated as requiring total knee arthroplasty. The 3D images of the femurs were clipped according to the following procedures. The distal femur was cut perpendicular to the mechanical axis at 10 mm proximal from the medial condyle. Rotational alignment was fixed at 3 degrees external rotation from the posterior condylar line. The anterior condyle was resected using the anterior cortex as the reference point. The posterior condyle was cut at 10 mm anterior from the medial posterior condyle. The medial-lateral (ML) width/anterior-posterior (AP) length was 1.58 ± 0.14 (mean ± SD). AP length of the 3D images tended to be longer than the box length of the three kinds of components provided when the ML width of the images was approximately equal to that of each component. The widths of medial and lateral posterior condyles of the images were 30.1 ± 3.8 mm and 24.8 ± 3.0 mm, respectively. In all except one case, the widths of the resected medial posterior condyles were greater than those of the medial condyles of all components when those of resected lateral posterior condyles were equal to those of the lateral condyles of the components. The shapes of the resected femoral surface did not always match those of the components. The configuration of Japanese knee joints is different from that of American knee joints. Components with appropriate geometry should be designed for Japanese patients.
Flexion after total knee arthroplasty (TKA) has recently been improved by changing implant designs, surgical techniques and early postoperative rehabilitation protocols. Especially for Asian people, deep knee flexion is essential because of their life style. Small numbers of patients can achieve full flexion after TKA, however, most current prostheses are not designed to allow deep knee flexion safely. Furthermore, the kinematics involved in knee flexion greater than 90 degrees in cases of TKA is still unknown, even though fluoroscopic studies have shown the paradoxical anterior femoral translation in posterior cruciate retaining (CR) TKA with knee flexion up to 90 degrees. The purpose of this study was to determine the femoro-tibial contact pattern in deep knee flexion. The knee that had been operated upon was passively flexed from 90 degrees up to the maximum flexion under anesthesia soon after the surgery. Lateral roentgenograms of the knee were taken during flexion, and the three-dimensional kinematics was analyzed using image-matching techniques. Nine patients with CR type were included. The average maximum flexion angle was 131.8 °. The contact point moved posteriorly with deep knee flexion except for one patient. Five out of nine patients showed external rotation of the femoral condyle. Two patients showed internal rotation, and the other two exhibited no rotational movement. None of the patients showed dislocation or disengagement of the components. At the maximum flexion, the edge of the posterior flange of the femoral component contacted the polyethylene insert. This study was performed under non-weight-bearing conditions, but deep knee flexion is not usually performed in weight-bearing conditions. Most of the CR type showed posterior roll back during deep knee flexion. The design of the posterior flange of the femoral component should be changed to prevent damage to the polyethylene.
Our study evaluated the accuracy of an image-guided total knee replacement system based on CT with regard to preparation of the femoral and tibial bone using nine limbs from five cadavers. The accuracy was assessed by direct measurement using an extramedullary alignment rod without radiographs. The mean angular errors of the femur and tibia, which represent angular gaps from the real mechanical axis in the coronal plane, were 0.3° and 1.1°, respectively. The CT-based system, provided almost perfect alignment of the femoral component with less than 1° of error and excellent alignment with less than 3° of error for the tibial component. Our results suggest that standardisation of knee replacement by the use of this system will lead to improved long-term survival of total knee arthroplasty.
The histology and mechanics of leg lengthening by callus distraction were studied in 27 growing rabbits. Tibial diaphyses were subjected to subperiosteal osteotomy, held in a neutral position for 10 days and then slowly distracted at 0.25 mm/12 hours, using a dynamic external fixator. Radiographs showed that the gap became filled with callus having three distinct zones. Elongation appeared to occur in a central radiolucent zone; this was bounded by two sclerotic zones. Histologically, the radiolucent zone consisted of longitudinally arranged cartilage and fibrous tissue while the sclerotic zones were formed by fine cancellous bone. New bone occasionally contained islands of cartilage, suggesting it had been formed by endochondral ossification. After completion of distraction, the two sclerotic zones fused, shrank and were eventually absorbed, leaving tubular bone with a new cortex. When the periosteum had been removed at the operation, callus formation was markedly disturbed and there was failure of bone lengthening. Scraping of endosteum, in contrast, did not have a pronounced effect. These results suggest that the preservation of periosteum is essential if bone lengthening by callus distraction is to succeed, and that preservation of the periosteum is more important than careful corticotomy.
