Aims

Pelvic discontinuity is a challenging acetabular defect without a consensus on surgical management. Cup-cage reconstruction is an increasingly used treatment strategy. The present study evaluated implant survival, clinical and radiological outcomes, and complications associated with the cup-cage construct.

Aims

The aim of this study was to report the outcome of femoral condylar fresh osteochondral allografts (FOCA) with concomitant realignment osteotomy with a focus on graft survivorship, complications, reoperation, and function.

This study reports the clinical outcome of reconstruction of deficient abductor muscles following revision total hip arthroplasty (THA), using a fresh–frozen allograft of the extensor mechanism of the knee. A retrospective analysis was conducted of 11 consecutive patients with a severe limp because of abductor deficiency which was confirmed on MRI scans. The mean age of the patients (three men and eight women) was 66.7 years (52 to 84), with a mean follow-up of 33 months (24 to 41).

Following surgery, two patients had no limp, seven had a mild limp, and two had a persistent severe limp (p = 0.004). The mean power of the abductors improved on the Medical Research Council scale from 2.15 to 3.8 (p < 0.001). Pre-operatively, all patients required a stick or walking frame; post-operatively, four patients were able to walk without an aid. Overall, nine patients had severe or moderate pain pre-operatively; ten patients had no or mild pain post-operatively.

At final review, the Harris hip score was good in five patients, fair in two and poor in four.

We conclude that using an extensor mechanism allograft is relatively effective in the treatment of chronic abductor deficiency of the hip after THA when techniques such as local tissue transfer are not possible.

Longer-term follow-up is necessary before the technique can be broadly applied.

Cite this article: Bone Joint J 2015;97-B:1050–5.

Cartilage defects of the hip cause significant pain and may lead to arthritic changes that necessitate hip replacement. We propose the use of fresh osteochondral allografts as an option for the treatment of such defects in young patients. Here we present the results of fresh osteochondral allografts for cartilage defects in 17 patients in a prospective study. The underlying diagnoses for the cartilage defects were osteochondritis dissecans in eight and avascular necrosis in six. Two had Legg-Calve-Perthes and one a femoral head fracture. Pre-operatively, an MRI was used to determine the size of the cartilage defect and the femoral head diameter. All patients underwent surgical hip dislocation with a trochanteric slide osteotomy for placement of the allograft. The mean age at surgery was 25.9 years (17 to 44) and mean follow-up was 41.6 months (3 to 74). The mean Harris hip score was significantly better after surgery (p < 0.01) and 13 patients had fair to good outcomes. One patient required a repeat allograft, one patient underwent hip replacement and two patients are awaiting hip replacement. Fresh osteochondral allograft is a reasonable treatment option for hip cartilage defects in young patients.

Cite this article: Bone Joint J 2014;96-B(11 Supple A):11–16.

Purpose

Cross-linking of polyethylene greatly reduces its wear rate in hip simulator studies. We conducted a systematic review and meta-analysis of randomized controlled trials comparing cross-linked to conventional polyethylene liners for total hip arthroplasty to determine if there is a clinical reduction of: 1) wear rates, 2) radiographic osteolysis, and 3) need for total hip revision.

Purpose

Femoroacetabular impingement (FAI) may contribute to the development of early onset hip osteoarthritis (OA). A cam lesion (or pistol grip deformity) of the proximal femur reduces head-neck offset resulting in cam type FAI. The alpha angle is a radiographic measurement recommended for diagnosis of cam type FAI. The purpose of this study was to determine if patients that develop end stage hip OA prior to 55 years of age have radiographic evidence of cam type FAI.

The treatment of substantial proximal femoral bone loss in young patients with developmental dysplasia of the hip (DDH) is challenging. We retrospectively analysed the outcome of 28 patients (30 hips) with DDH who underwent revision total hip replacement (THR) in the presence of a deficient proximal femur, which was reconstructed with an allograft prosthetic composite. The mean follow-up was 15 years (8.5 to 25.5). The mean number of previous THRs was three (1 to 8). The mean age at primary THR and at the index reconstruction was 41 years (18 to 61) and 58.1 years (32 to 72), respectively. The indication for revision included mechanical loosening in 24 hips, infection in three and peri-prosthetic fracture in three.

Six patients required removal and replacement of the allograft prosthetic composite, five for mechanical loosening and one for infection. The survivorship at ten, 15 and 20 years was 93% (95% confidence interval (CI) 91 to 100), 75.5% (95% CI 60 to 95) and 75.5% (95% CI 60 to 95), respectively, with 25, eight, and four patients at risk, respectively. Additionally, two junctional nonunions between the allograft and host femur required bone grafting and plating.

An allograft prosthetic composite affords a good long-term outcome in the management of proximal femoral bone loss in revision THR in patients with DDH, while preserving distal host bone.

Purpose: The purpose of this study was to evaluate the accuracy and precision of 3 common methods used to produce posterior tibial slope during total knee arthroplasty.

Method: The study population consisted of 110 total knee arthroplasties in 102 patients that underwent total knee arthroplasty. All procedures were performed using a standard medial parapatellar approach and all knees were replaced using the Scorpio Knee System (Stryker, Mahwah, NJ) of implants and instruments. Three treatment groups were identified retrospectively based on the method used to produce the posterior tibial slope. Group 1 used an extramedullary guide with a 0 degree cutting block tilted by placing 2 fingers between the tibia and the extramedullary guide proximally and three fingers between the tibia and guide distally to produce a 3 degree posterior slope (N=40). Group 2 used computer navigation (Stryker Navigation System, Stryker, Mahwah, NJ) to produce a 3 degree posterior slope (N=30). Group 3 used an extramedullary guide placed parallel to the anatomic axis of the tibia with a 5 degree cutting block to produce a 5 degree posterior slope (N=40). Posterior tibial slope was measured from lateral radiographs by 2 independent reviewers that were blinded to the treatment group. The reported posterior tibial slope for each sample was an average of these two measurements. Accuracy of the treatment group was evaluated using a one sample t test. Groups 1 and 2 were tested for an ideal slope of 3 degrees, and Group 3 was tested for an ideal slope of 5 degrees. An a priori sample size calculation with α=0.05 and β=0.20 showed that at least 24 samples in each treatment group were required to determine a difference of 1.5 degrees between the treatment group mean posterior tibial slope and the ideal posterior tibial slope.

Results: The mean posterior slope measurements for treatment Group 1 (4.15±3.24 degrees) and treatment Group 2 (1.60±1.62 degrees) were both significantly different than the ideal slope of 3 degrees (p=0.03 for Group 1 and p< 0.01 for Group 2). This indicates that treatment Groups 1 and 2 failed to accurately produce the ideal posterior tibial slope of 3 degrees. The mean posterior tibia slope of treatment Group 3 (5.00±2.87 degrees) was not significantly different than the ideal posterior tibial slope of 5 degrees (p=1.00). This indicates that Group 3 accurately produced the ideal tibial slope of 5 degrees.

Conclusion: The most accurate method to produce posterior tibial slope was the 5 degree cutting block with an extramedullary guide. Computer navigation had the lowest standard deviation and therefore was the most precise method. However, computer navigation was not as accurate in producing the desired posterior tibial slope as the extramedullary guide with the 5 degree cutting block. The manual method of producing tibial slope with an extramedullary guide and a 0 degree cutting block was the least precise method and not as accurate as the extramedullary guide with a 5 degree cutting block.

Purpose: Optimal fixation for comminuted proximal humerus fractures is controversial. Complications using locked plates have been addressed by anatomic reduction or medial cortical support. The current study measured relative mechanical contributions of varus malalignment and medial cortical support.

Method: Forty synthetic humeri were divided into three groups, osteotomized, and fixed at 0, 10, and 20 degrees of varus malreduction with locked proximal humerus plates (AxSOS, Global model, Stryker, Mahwah, NJ, USA). This simulated mechanical medial support with the cortex intact. Axial, torsional, and shear stiffness were experimentally measured. Half of the specimens in each of the groups underwent a second osteotomy to create a segmental defect which simulated loss of medial support with the cortex removed. Axial, torsional, and shear stiffness experiments were repeated, followed by shear load to failure in 20 degrees of abduction.

Results: For isolated malreduction with the cortex intact, the repair construct at 0 degrees showed statistically equivalent or higher axial, torsional, and shear stiffness than other groups assessed. Subsequent removal of cortical support in half the specimens resulted in a drastic effect on axial, torsional, and shear stiffness at all varus angles. Repair constructs with the cortex intact at 0 and 10 degrees resulted in mean shear failure forces of 12965.4 N and 9341.1 N, respectively. These were statistically higher (p< 0.05) compared to most other groups tested. Specimens failed mainly by plate bending as the femoral head was pushed down medially and distally.

Conclusion: Anatomic reduction with the medial cortex intact was the stiffest construct after a simulated two-part fracture. This study also supports the practice of achieving medial cortical support by fixing proximal humeral fractures in varus if necessary. This may be preferable to fixing the fracture in anatomic alignment when there is a medial fracture gap.

Purpose: Minimizing tip-apex distance (TAD) has been shown to reduce clinical failure of extramedullary sliding hip screws used to fix peritrochanteric fractures. There is debate regarding the optimal position of the lag screw in the femoral head when a cephalomedullary nail is used to treat a peritrochanteric fracture. Some authors suggest the TAD should be minimized as with an extramedullary sliding hip screw, while others suggest the lag screw should be placed inferior within the femoral head. The primary goal of this study was to determine which of 5 possible lag screw positions in the femoral head provides greatest mechanical stiffness and/or load-to-failure for an unstable peritrochanteric fracture treated with a cepha-clomedullary nail. The secondary goal was to determine if there is a linear correlation between implant-femur mechanical stiffness and/or load to failure (dependent variables) with a series of five radiographic measurements (independent variables) of distance from the lag screw tip to the femoral head apex.

Method: Long Gamma 3 Nails (Stryker, Mahwah, NJ) were inserted into 30 left synthetic femurs (Pacific Research Laboratories, Vashon, WA). An unstable four-part fracture was created, anatomically reduced, and repaired using one of 5 lag screw placements in the femoral head:

superior (n=6),

All specimens were radiographed in the anterioposterior and lateral planes, and radiographic measurements including TAD and a calcar referenced tip-apex distance (CalTAD) were calculated. All specimens were tested for axial, lateral, and torsional stiffness, and then loaded-to-failure in the axial position using an Instron 8874 (Canton, MA). ANOVA was used to compare means of the five treatment groups. Linear regression analysis was used to compare stiffness and load-to-failure (dependant variables) with radiographic measurements (independent variables). A post hoc power analysis was performed.

Results: The inferior lag screw position had significantly greater mean axial stiffness than superior (p< 0.01), anterior (p=0.02) and posterior (p=0.04) positions. Analysis revealed significantly less mean torsional stiffness for the superior lag screw position compared to other lag screw positions (p< 0.01 all 4 pairings). No statistical differences were noted for lateral stiffness. Superior and central lag screw positions had significantly greater mean load-to-failure than anterior (p< 0.01 and p=0.02) and posterior (p< 0.01 and p=0.05) positions.

There were significant negative linear correlations between stiffness tests with CalTAD, and load-to-failure with TAD. Power was greater than 95% for axial stiffness, torsional stiffness and load-to-failure tests.

Conclusion: Position of the lag screw in the femoral head affects the biomechanical properties of the implant-femur construct. Central placement of the lag screw with minimization of TAD may provide the best combination of stiffness and load-to-failure.

Purpose: Cephalomedullary nails rely on a large lag screw that provides fixation into the femoral head. There is an option to statically lock the lag screw (static mode) or to allow the lag screw to move within the nail to compress the intertrochanteric fracture (dynamic mode). The purpose of this study was to compare the biomechanical stiffness of static and dynamic modes for a cephalomedullary nail used to fix an unstable peritrochanteric fracture.

Method: Thirty intact synthetic femur specimens (Model #3406, Pacific Research Laboratories, Vashon, WA) were potted into cement blocks distally for testing on an Instron 8874 (Instron, Canton, MA). A long cephalomedullary nail (Long Gamma 3 Nail, Stryker, Mahwah, NJ) was then inserted into each of the femurs. An unstable four-part fracture was created, anatomically reduced, and the cephallomedullary nail was reinserted. Mechanical tests were conducted for axial, lateral, and torsional stiffness with the lag screws in:

static and

A paired student’s t test was used to compare the 2 modes.

Results: The axial stiffness of the cephalomedullary nail was significantly greater (p< 0.01) in the static mode (484.3±80.2N/mm) than in the dynamic mode (424.1±78.0N/mm) (Fig.2A). Similarly, the lateral bending stiffness of the nail was significantly greater (p< 0.01) in the static mode (113.9±8.4N/mm) than in the dynamic mode (109.5±8.8N/mm). The torsional stiffness of the nail was significantly greater (p=0.02) in the dynamic mode (114.5±28.2N/mm) than in the static mode (111.7±27.0N/mm).

A post hoc power analysis with & #945;=0.05 and & #946;=0.20 revealed that the paired t test on 30 samples was sufficiently powered to determine a difference in mean axial stiffness of 33.0N/mm (6.8% of static stiffness), a difference in mean lateral bending stiffness of 3.6N/mm (3.2% of static stiffness) and a difference in mean torsional stiffness of 3.4N/mm (3.0% of static stiffness).

Conclusion: Our results show that there is a 60N/mm reduction in axial stiffness of the cephalomedullary nail when the lag screw is changed from static to dynamic mode. This represents a 12.4% reduction in axial stiffness with a change from axial to dynamic modes which may be clinically significant. The differences in lateral (4.4N/mm, 3.9%) and torsional (2.8N/mm, 2.4%) are small enough that they are likely not clinically significant. We felt that a difference of greater than 10% in axial stiffness and a difference of greater than 5% in lateral or torsional stiffness would be clinically significant. Our study was adequately powered to detect these differences. Given the significant reduction in axial stiffness with dynamization of the cephalomedullary nail construct, we recommend use of the static mode when treating unstable peritrochanteric fractures with a cephalomedullary nail.