Introduction

The prevalence of the various patterns of spinopelvic abnormalities that increase the risk for prosthetic impingement is unknown. While prior surgery or lumbar fusion are recognized as a risk factors for postoperative dislocation, many patients presenting for THA do not have obvious radiographic abnormalities. The purpose of this study is to determine the prevalence of large posterior pelvic tilt (PPT) when standing, stiff lumbar-spine (SLL) and spino-pelvic sagittal imbalance (SSI) in patients undergoing primary THA.

The role of unicompartmental knee arthroplasty (UKA) in spontaneous osteonecrosis of the knee (SONK) remains controversial, even though SONK usually involves only medial compartment of the knee joint. We aimed to compare the survival rate and clinical outcomes of UKA in SONK and medial compartment osteoarthritis (MOA) via a meta-analysis of previous studies. MEDLINE database in PubMed, the Embase database, and the Cochrane Library were searched up to January 2018 with keywords related to SONK and UKA. Studies were selected with predetermined inclusion criteria: (1) medial UKA as the primary procedure, (2) reporting implant survival or clinical outcomes of osteonecrosis and osteoarthritis, and (3) follow-up period greater than 1 year. Quality assessment was performed using the risk of bias assessment tool for non-randomised studies (RoBANs). A random effects model was used to estimate the pooled relative risk (RR) and standardised mean difference. The incidence of UKA revision for any reason was significantly higher in SONK than in MOA group (pooled RR = 1.83, p = 0.009). However, the risk of revision due to aseptic loosening and all- cause re-operation was not significantly different between the groups. Moreover, when stratified by the study quality, high quality studies showed similar risk of overall revision in SONK and MOA (p = 0.71). Subgroup analysis revealed worse survival of SONK, mainly related to high failure after uncemented UKA. Clinical outcomes after UKA were similar between SONK and MOA (p = 0.66). Cemented UKA has similar survival and clinical outcomes in SONK and MOA. Prospective studies designed specifically to compare the UKA outcomes in SONK and MOA are necessary.

Background

Occasionally, patients experience new or increased ankle pain following total knee arthroplasty (TKA). The aims of this study were to determine (1) how the correction of varus malalignment of the lower limb following TKA affected changes in alignment of the ankle and hindfoot, (2) the difference in changes in alignment of the ankle and hindfoot between patients with and without ankle osteoarthritis (OA), and (3) whether the rate of ankle pain and the clinical outcome following TKA differed between the 2 groups.

Background

Authors sought to determine the degree of lateral condylar hypoplasia of distal femur was related to degree of valgus malalignment of lower extremity in patients who underwent TKA. Authors also examined the relationships between degree of valgus malalignment and degree of femoral anteversion or tibial torsion.

Recently, concerns arose over the medial tibial bone resorption of a novel cobalt-chromium (CoCr) implant. This study aimed to investigate the effects of tibial component material, design, and patient factors on periprosthetic bone resorption and to determine its association with clinical outcomes after total knee arthroplasty (TKA). A total of 462 primary TKAs using five types of implants were included. To evaluate tibial periprosthetic bone resorption, we assessed radiolucent lines (RLL) and change in bone mineral density at the medial tibial condyle (BMDMT). Factors related to bone resorption were assessed using regression analysis. Clinical outcomes were also evaluated with respect to periprosthetic bone resorption. Compared to titanium (Ti) implants, CoCr implants showed a higher incidence of complete RLL (23.1% vs. 7.9% at two years post-TKA) and a greater degree of BMDMT reduction. However, there was no significant difference between the implants made of the same material. Increased medial tibial bone resorption was associated with male sex, osteoporosis, larger preoperative varus deformity, longer follow-up period, and lower body mass index. The periprosthetic bone resorption was not associated with clinical outcomes including changes in range of motion and WOMAC score. Furthermore, no cases warranted additional surgery. Periprosthetic bone resorption was associated with implant material but not with implant design. Moreover, patient factors were related to the medial tibial bone resorption post-TKA. However, the periprosthetic bone resorption was not associated with short-term clinical outcomes. We contend that researchers should incorporate integrative considerations when developing and assessing novel implants.

Purpose

We sought to determine whether there was a difference in the posterior condylar offset (PCO), posterior condylar offset ratio (PCOR) following total knee arthroplasty (TKA) with anterior referencing (AR) or posterior referencing (PR) systems. We also assessed whether the PCO and PCOR changes, as well as patient factors were related to range of motion (ROM) in each referencing system. In addition, we examined whether the improvements in clinical outcomes differed between the two referencing systems.

Background

Humeral retroversion is variable among individuals, and there are several measurement methods. This study was conducted to compare the concordance and reliability between the standard method and 5 other measurement methods on Twodimensional (2D) computed tomography (CT) scans.

Objectives

This study was conducted to evaluate the cytokine-release kinetics of platelet-rich plasma (PRP) according to different activation protocols.

Introduction

Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was to develop an experimental model which would simulate the clinical revision hip scenario and to determine the effects of alendronate coating on porous tantalum on gap filling and bone ingrowth in the experimental model.

Aims: Limb length discrepancy is a recognised complication of total hip arthroplasty (THA). Cementless THAs are increasingly being used, but in order to achieve rotational and axial stability larger implants may be required than originally templated for. This could potentially result in greater limb length discrepancy. Our objective was to determine if limb length discrepancy exists to a greater degree in cementless THA.

Methods: 166 consecutive patients undergoing elective THA between June 2007 and May 2008 were included in this retrospective study. Post-operative, digital radiographs (PACS, Centricity^®) were examined for each of these patients to determine limb length. Limb length discrepancy was calculated as the difference between the perpendicular distance between the inter-teardrop line and the most prominent points on the lesser trochanter of each limb. Magnification was determined from the measured radiographic diameter of the prosthetic heads and their actual diameters.

Results: Of the 166 patients included in this study 128 had cementless THA and 38 had cemented. The average magnification was calculated as 30%. Limb length discrepancy was found post-operatively in 93% of cases. In 65% of patients the operated limb was longer (by 0 – 29 mm) and in 28% it was shorter (by 0 – 23 mm). The mean limb length discrepancy, corrected for magnification, was 6.21 mm for cemented THA and 6.22 mm for cementless THA. A student’s T-test demonstrated no significant difference in limb length discrepancy between these operations (p = 0.996).

Conclusions: The incidence of limb length discrepancy after THA is high. However, no significant differences were demonstrated between cemented and cementless THAs in our series. Accurate and careful pre-operative templating is important in THA to minimise the risk of clinically significant limb length discrepancy.

Purpose: Porous tantalum has been shown to be very effective in achieving bone ingrowth. However, in some circumstances, bone quality or quantity is insufficient to allow adequate bone ingrowth. We hypothesized that the addition of alendronate to porous tantalum would enhance the ability of porous tantalum to achieve bone ingrowth in these challenging situations, such as when a gap exists between the implant and bone. We evaluated the effect of alendronate coated porous tantalum on new bone formation in an animal model incorporating a gap between implant and bone.

Method: Thirty-six cylindrical porous tantalum implants were bilaterally implanted into the distal femur of 18 rabbits for 4 weeks. There were 3 groups of implants inserted; a control group of porous tantalum with no coatings, porous tantalum with micro-porous calcium phosphate coating, and porous tantalum coated with micro-porous calcium phosphate and alendronate. Subcutaneous fluorescent labeling was used to track new bone formation. Bone formation was analyzed by backscattered electron microscopy and fluorescent microscopy on undecalcified samples.

Results: The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 143% (p< 0.001), 259% (p< 0.001) and 193% (p< 0.001) respectively in the alendronate coated porous tantalum compared with the uncoated porous tantalum controls. The relative increase in the percentage of new bone-implant contact length was increased by 804% on average in the alendronate coated porous tantalum compared with the uncoated tantalum controls.

Conclusion: This study demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss (at the hip, knee or elsewhere), the addition of an alendronate-delivery surface coating would enhance biological fixation of the implant and promote the healing of bone defects.

Purpose: Fresh osteochondral allograft (FOCA) transplantation has been an effective treatment option with promising long-term clinical outcomes for focal post-traumatic or intra-articular lesions in the knee for young, active individuals. The goal of this study was to assess the osteochondral allograft to characterize the histopathologic features of early and late graft failure, as well as prolonged graft survival.

Method: We examined histological features of thirtyfive fresh osteochondral allograft specimens retrieved at the time of subsequent graft revision, osteotomies or total knee arthroplasty.

Results: The graft survival time in our samples ranged from one to twenty-five years based on their time to reoperation. Histological features of early graft failures were lack of chondrocyte viability, loss of matrix cationic staining, and features of mechanical instability. Histological features of late graft failures were fracture through the graft, active and incomplete remodelling of the graft bone by the host bone, and resorption of the graft tissue by synovial inflammatory activity at graft edges. Histological features associated with long-term allograft survival included viable chondrocytes, functional preservation of matrix, and complete replacement of the graft bone with the host bone. These long-term histological findings correlate clinically with excellent Oxford Knee Scores (mean 17.5) in age-matched cohorts with allograft transplants surviving 20 (mean 20.9) years or longer.

Conclusion: Given chondrocyte viability, long-term allograft survival depends on graft stability by rigid fixation of host bone to graft bone. With the stable osseous graft base, the hyaline cartilage portion of the allograft can survive and function for 25 years or more.

Introduction: Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was

to develop an experimental model which would simulate the clinical revision hip scenario and

Methods: Thirty-six porous tantalum plugs were implanted into the distal femur, bilaterally of 18 rabbits for four weeks. There were 3 groups of plugs inserted; control groups of porous tantalum plugs (Ta) with no coating, a 2nd control group of porous tantalum plugs with micro-porous calcium phosphate coating, (Ta-CaP) and porous tantalum plugs coated with alendronate (Ta-CaP-ALN). Subcutaneous fluorochrome labelling was used to track new bone formation. Bone formation was analysed by backscattered electron microscopy and fluorescence microscopy on undecalcified histological sections.

Results: The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 124 %, 232 % and 170 % respectively in Ta-CaP-ALN compared with the uncoated porous tantalum (Ta) controls, which was statistically significant. The contact length of new bone formation on porous tantalum implants in Ta-CaP-ALN was increased by 700% (8-fold) on average compared with the uncoated porous tantalum (Ta) controls.

Discussion: Alendronate coated porous tantalum significantly modulated implant bioactivity compared with controls. This study has demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth, which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss, the addition of alendronate as a surface coating would enhance biological fixation of the implant and promote the healing of bone defects.

Objective: The purpose of this study was to determine the safety and efficacy and evaluate several radiographic parameters after implantation of coflex™ for the primary diagnosis of spinal stenosis (1 or 2 levels) in patients with neurogenic claudication and low back pain between the ages of 40 and 80 years old.

Methods: Retrospective data were gathered on 589 patients from 5 sites with 429 patients having contemporaneous clinical and radiographic follow-up. Clinical analysis was performed on 209 patients with spinal stenosis using VAS and objective examination measures to determine safety and efficacy of the coflex in relieving neurogenic claudication, radiculopathy and back pain. The median follow-up was 20 months (range 6 to 121 months) For the 209 patients, radiographic data was collected for evaluation of spinal segment motion (index and adjacent levels), implant position, migration and bony remodeling at the bone-implant interface. All device complications were recorded and independently reviewed by Medical Metrics, Inc. (Houston, TX) and an independent orthopaedic spinal surgeon (KP).

Results: Moderate to severe low back pain improved in 75% of patients, while leg pain improved in 88% of patients. Claudication improved in 91% of patients and improvement in walking distance occurred in 79% of the patients. These results were achieved at 1 year and did not deteriorate over the long-term. Patient satisfaction was 88%. Complete radiographs with excellent quality were available for 180 implanted coflex devices. Sagittal rotation and translation measurements were essentially the same for all diagnoses, follow-up time points and levels of implantation. No expulsions and only 1 migration (> 5 mm) was observed. Mild and moderate bone-implant interface remodeling was noted in 15.4 %. No broken or permanently deformed implants were noted.

Conclusions: coflex interspinous stabilization after microsurgical decompression for spinal stenosis demonstrates excellent short term and long term results for back pain, neurogenic claudication and patient satisfaction.

We describe a successful modified operative procedure at an average 19 months follow-up in 3 patients with congenital dislocation of the patella and compare its merits to the other procedures already reported in the literature.

Congenital dislocation of the patella may be associated with other congenital conditions or syndromes i.e. Down’s syndrome, congenital vertical talus and cerebral palsy. Numerous operative techniques have been described in the literature which may be divided into 3 basic groups. A modification of the Langenskiold & Ritsila procedure is described. The original procedure describes an extensive lateral release with detachment and medial transfer of the patellar tendon through a curved incision. The tendon is routed through a fold of synovium medially and fixed distally to bone with sutures through drill holes in the proximal tibia. We found at surgery this synovium was too fragile to hold the transferred tendon and the use of drill holes unnecessary. The main alterations include a limited and straight anterior skin incision, a fashioning of a ‘buckle’ of the transferred distal patellar tendon to a distally based flap which avoids drill holes in the growing bone. This modification of the Langenskiold procedure was used successfully in 3 cases, including a revision of a failed Goldthwaite- Roux procedure in a mentally handicapped child. The results at average 19 months follow-up are successful. The early results confirm that the patella remains located and tracks normally. The valgus and flexion deformities have significantly improved.

This modification of the Langenskiold & Ritsila procedure requires less dissection than other operations, with no bony surgery and a cosmetic scar. The Langen-skiold & Ritsila procedure has been successful and we feel that this modification simplifies and improves on the original technique.

The purpose of this study was to investigate the effects of varying tire pressures on rolling resistance of pneumatic wheelchair tires and compare the rolling resistance of pneumatic versus solid wheelchair tires.

Our study demonstrated that, statistically significant increases in rolling resistance occurred at and below 50% of the recommended tire pressures (RTP) for the pneumatic tires tested. Also, solid tires performed worse than pneumatic tires at 25% (RTP).

Shoulder pain among the spinal cord injured wheelchair users is reported between 60–100%. Despite the shoulder problems, it’s not uncommon to see WC users with low or flat tires. To reduce the need for regular inflating of tires, people have switched to the popular solid tire. Unfortunately, based on our results, the use of the popular solid tires may still contribute to repetitive strain disorders in wheelchair users.

Compared to the recommended tire pressures the pneumatic tires showed statistically significant decreases in rolling distance at 25% and 50% RTP. The rolling distances of the two solid tires performed similarly to 25% RTP of the pneumatic tires.

This prospective study measured the differences in rolling resistance of five types of commonly used wheelchair tires (three pneumatic: two solid: under four different tire pressures (100%, 75%, 50% and 25% RTP) using a standardized roll down test ramp and a wheelchair with a 56 kg load. Four samples of rolling distances (five per tire pressure per sample) were measured for each tire type and analyzed (repeated measure ANOVA).

The changes of stress distribution in the femoral head with Perthes disease were observed under several condition. Finite element models were constructed referring to X-ray images and magnetic resonance images of the intact hip joint. The model was divided into five parts: cancellous bone, articular cartilage, necrotic bone, cortical bone, physeal cartilage. Material properties were alloted to these components by the past literature. The body weight and abductor muscle force were applied as loading. The model was altered to study the effect of age, the extent of necrosis, and lateralization of the fomoral head. Analysis were performed on a digital computer PC-9821(NEC) using the finite element program. There was no significant difference in stress distribution patterns regardless of age or extent of necrosis. However, compressive stresses were concentrated on the lateral portion of the epiphysis by lateralization of femoral head. The femoral head deformity in Perthes disease was more affected by the lateralization than by the age and the extent of necrosis.