Early Functional Outcomes After Evolutionary Total Knee Arthroplasty: A Randomized Controlled Trial. Is New Always Better?

Total knee replacement (TKR) designs continue to evolve with the aim of improving patient outcomes; however, there remains a significant patient dissatisfaction rate. We report the early functional outcomes of an evolutionary knee design in the context of a single-blinded, noninferiority, randomized controlled trial. METHODS: Patients were randomized to receive either the P.F.C. SIGMA or ATTUNE knee implant systems (DePuy Synthes). All implants were fixed-bearing, cruciate-retaining, and cemented constructs. Patients were assessed at baseline and 6 weeks, 3 months, and 1 year postoperatively using clinical and functional outcome measures, including range of motion, Oxford Knee Score (OKS), Oxford Knee Score-Activity and Participation Questionnaire (OKS-APQ), Patient Knee Implant Performance (PKIP) score, 5-Level EuroQol 5 Dimensions (EQ-5D-5L), and Short Form-36 outcome measures. RESULTS: There were 150 patients who underwent a surgical procedure (76 with the ATTUNE implant and 74 with the P.F.C. SIGMA implant), with 147 patients remaining at the final review. No differences were observed in any of the outcome measures between the groups at any time point. Tourniquet time was significantly shorter in the P.F.C. SIGMA arm (p = 0.001); however, this had no clinical impact on the OKS (analysis of covariance [ANCOVA] test) at the final review (p = 0.825). There was no difference in the numbers of patients achieving the minimal clinically important difference for the OKS between the groups (p = 0.817). CONCLUSIONS: This trial did not show inferiority of the ATTUNE implant when compared with the P.F.C. SIGMA implant. The authors believe that implant innovation should continue and that modern implants should be introduced into the market following randomized controlled trials. Further work should assess the effect of non-implant-related factors on patient outcomes. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Impaction bone grafting for periprosthetic fractures around a total hip arthroplasty.

The incidence of periprosthetic fractures has been reported to be between 1 and 20.9% and appears to be on the rise. Fractures that occur around the femoral stem, particularly when the stem is loose or there is a loss of bone stock pose a technical challenge. These are rare injuries and there is considerable debate regarding their optimal treatment. Reconstruction with large segment endoprosthetic replacement is an acceptable solution for elderly patients who have limited functional demands and where the prosthesis is expected to outlive the patient. The younger patient poses a much greater challenge, the bone must be reconstituted and the femoral canal geometry must sufficiently restored to allow the stable insertion of a prosthesis. There are very few techniques that exist in this scenario. One such technique is impaction bone grafting and revision to a long smooth tapered cemented stem. This allows the restoration of bone stock and the stable insertion of a prosthesis. The aim of this article is to discuss the theory behind impaction bone grafting, the technical aspects and challenges of this technique, including fracture reduction methods, and to appraise all the literature available on impaction bone grafting for periprosthetic fractures.

Biomechanical characteristics of bone in streptozotocin-induced diabetic rats: An in-vivo randomized controlled experimental study.

AIM: To investigate the in vivo effects of type I diabetes on the mechanical strength of tibial bone in a rodent model. METHODS: The biomechanical effect of diabetes on the structural integrity of the tibia in streptozotocin induced diabetic Wistar rats was analysed. Induction of diabetes was achieved by an intra-peritoneal injection and confirmed by measuring serial blood glucose levels (> 150 mg/dL). After 8 wk the tibiae were harvested and compared to a control group. Biomechanical analysis of harvested tibiae was performed using a three-point bending technique on a servo hydraulic MTS 858 MiniBionix frame. Maximum force applied to failure (N), stiffness (N × mm) and energy absorbed (N/mm) were recorded and plotted on load displacement curves. A displacement control loading mode of 1 mm/min was selected to simulate quasi-static loading conditions. Measurements from load-displacement curves were directly compared between groups. RESULTS: Fourteen streptozotocin induced diabetic Wistar rats were compared against nineteen non-diabetic controls. An average increase of 155.2 g in body weight was observed in the control group compared with only 5 g in the diabetic group during the experimental study period. Levels of blood glucose increased to 440.25 mg/dL in the diabetic group compared to 116.62 mg/dL in the control group.The biomechanical results demonstrate a highly significant reduction in the maximum load to failure from 69.5 N to 58 N in diabetic group compared to control (P = 0.011). Energy absorption to fracture was reduced from 28.2 N in the control group to 23.5 N in the diabetic group (P = 0.082). No significant differences were observed between the groups for bending stiffness. CONCLUSION: Streptozotocin-induced diabetes in rodents reduces the maximum force and energy absorption to failure of bone, suggesting a predisposition for fracture risk.

Management of pubic symphysis diastasis with locking plates: a report of 11 cases.

INTRODUCTION: The optimal method of fixation of symphyseal disruptions in pelvic ring injuries and post-operative rehabilitation is still debated. Options include two-hole, multi-hole and multiplanar plates. Post-operative rehabilitation can range from non-weight bearing bilaterally to full weight-bearing with crutches. Locking symphyseal plates have recently been introduced. There is a paucity of literature evaluating their use in such injuries. We present the first clinical case series of symphyseal diastasis managed with locking plates. METHODS: A retrospective analysis of a single centre case series between August 2008 and December 2011 was conducted. A total of 11 patients; 2 females and 9 males with a mean age of 42 years were included. The mean radiological follow up was 27 weeks. Radiological failure and need for revision were evaluated. RESULTS: 4 patients sustained their injury as a result of a motorcycle accident, 3 patients following a car accident, 2 fell from a height and 2 had crush injuries. 9 patients had other concomitant injuries. The mechanism of injury was classified as anterior-posterior compression injury in 6 patients, vertical shear in 4 patients and combined mechanism in 1 patient. 6 patients required posterior pelvic fixation. Patients were mobilised fully or partially weight bearing. One patient had a significant radiological failure. All patients were asymptomatic at last follow-up and none required revision surgery. CONCLUSION: Our series represents the first published clinical series of patients with symphyseal diastasis managed with locking plates. We have found the use of locking plates across the pubic symphysis to be safe with low complication rates despite early weight bearing.

Modern management of patellar instability.

Recurrent patellofemoral instability is a disabling condition, attributed to a variety of anatomical aetiologies. Trochlear dysplasia, patella alta, an increased tibial tubercle trochlear groove distance of greater than 20 mm and soft tissue abnormalities such as a torn medial patellofemoral ligament and inadequate vastus medialis obliquus are all factors to be considered. Management of this condition remains difficult and controversial and knowledge of the functional anatomy and biomechanics of the patellofemoral joint, a detailed history and clinical examination, and an accurate patient assessment are all imperative to formulate an appropriate management plan. Surgical treatment is based on the underlying anatomical pathology with an aim to restore normal patellofemoral kinematics. We summarise aspects of assessment, treatment and outcome of patellofemoral instability and propose an algorithm of treatment.

Pharmacological treatment of heterotopic ossification following hip surgery: an update.

Heterotopic ossification is a frequent complication following total hip arthroplasty and acetabular surgery. Formation of ectopic lamellar bone in tissues that exhibit no potential for ossification can lead to associated pain and decrease in function. Prophylaxis and treatment protocols aim to reduce the incidence, by both the use of nonsteroidal anti-inflammatory drug (NSAID) regimens and localized radiotherapy. New therapeutic modalities including bone morphogenetic proteins (BMP) inhibitors like Noggin, BMP type 1 receptor inhibition, nuclear retinoic acid receptor-gamma agonists (RAR-γ), and free radical scavengers are currently under investigation.

Risk factors for heterotopic ossification in primary total hip arthroplasty.

Heterotopic ossification (HO) is a recognised complication of total hip arthroplasty (THA). This study aims to correlate demographics, surgical approach and type of arthroplasty to the incidence of HO in an attempt to quantify patient risk. A total of 920 primary THAs in 893 patients were performed between 2006 and 2008 in a single arthroplasty centre. Radiographic evaluation was conducted and all cases of HO were classified using the Brooker classification. Age, sex, arthroplasty type and surgical approach were all considered as variables. Arthroplasty type was classified into four groups; total cemented (TC), total uncemented (TU), hybrid (H) and reverse hybrid (RH). Two-level logistic regression analysis was conducted. The overall incidence of HO was 24%. Male sex [OR=3.57, 95% CI (1.79-7.10); p=0.001], lateral approach [OR=2.47, (95% CI 1.23-4.95); p=0.001] and total cemented implants [OR=3.14, (95%CI 1.37-7.23); p=0.007] were significantly associated with HO. The intra-class correlation coefficient was 0.52 [95% CI (0.21, 0.81); p=0.004], demonstrating that patients with previous HO to one THA were very likely to suffer HO in subsequent THA. The results demonstrate very large effects for sex, surgical approach, and implant type on HO incidence. This raises a three arm hypotheses that reaming of the femoral canal for the insertion of cemented implants contaminates the surgical field with bone marrow increasing the risk of HO, whereas modern cementless implants generally employ impaction broaching. In addition surgical insult to the hip abductors during exposure, particularly in males due to higher muscle mass, may also predispose to HO.

Patellar resurfacing in total knee arthroplasty: does design matter? A meta-analysis of 7075 cases.

BACKGROUND: Patellar resurfacing in total knee arthroplasty remains controversial. The aim of this study was to compare outcomes following total knee arthroplasty with patellar resurfacing with those following total knee arthroplasty without patellar resurfacing. We also sought to identify any correlation between outcomes and prosthetic design. METHODS: Eighteen Level-I randomized controlled trials with a cumulative sample size of 7075 knees (3463 in the resurfacing group and 3612 in the non-resurfacing group) satisfied the inclusion criteria. In the primary analysis, patellar resurfacing total knee arthroplasty was compared with non-resurfacing total knee arthroplasty, with use of reoperation rates, incidence of anterior knee pain, and functional scores as outcome measures. The secondary analysis focused on comparing patella-friendly and non-patella-friendly total knee arthroplasty designs with regard to the same three outcome measures. RESULTS: No significant differences were found between the resurfacing and non-resurfacing groups with regard to the incidence of anterior knee pain. A higher rate of reoperations was observed in the non-resurfacing group. Analysis of homogeneous data comparing patella-friendly with non-patella-friendly total knee arthroplasty designs demonstrated no differences in the incidence of reoperations. CONCLUSIONS: No evidence was found to suggest that either patellar resurfacing or the prosthetic design affects the clinical outcome of a total knee arthroplasty. The higher incidence of reoperations in the non-resurfacing group may be attributed to the fact that secondary patellar resurfacing adds a surgical option for the treatment of anterior knee pain following total knee arthroplasty, thus artificially increasing the rate of reoperations in the non-resurfacing group.

A review of 202 periprosthetic fractures--stem revision and allograft improves outcome for type B fractures.

We report a retrospective review of the outcome of treatment of 202 periprosthetic fractures around total hip arthroplasty (THA) from two specialised arthroplasty centres. Fractures were classified according to the Vancouver classification. The aim was to evaluate treatment methods with respect to stem revision and grafting. Transverse B1 fractures treated with stem revision compared to those treated with open reduction and internal fixation (ORIF) with a plate showed a trend towards improved overall union rate (OR=2, p=0.6, 95% CI:0.14-28.4) and shorter times to union (p=0.038, mean 12 months SD 6.573 for ORIF versus 4.48 months SD 0.757 for stem revision). B2 fractures undergoing stem revision and grafting were significantly more likely to unite compared to ORIF alone (OR=17.3, p=0.018 95%CI:1.63-184.4). B3 fractures presented with significant variation in fracture configuration and bone loss and therefore their treatment was individualised. When treated with stem revision and grafting healing was achieved in a mean time of 7 months (n=81). Periprosthetic fractures of the femur are highly complex and challenging. Stem revision for transverse B1 fractures is now considered as a viable treatment modality as this fracture configuration is difficult to control with single plating, and fixation with a long stem bypassing the distal fracture line is necessary to achieve axial stability and healing. Bone allografting, whether used as a cortical onlay or in morselised impacted form for B2 and B3 fractures enhances fracture healing.

Surgical treatment of tuberculous paraparesis in the third trimester: a report of two cases and review of the literature.

BACKGROUND: Tuberculous paraplegia as a consequence of spinal infiltration in pregnancy is reported to be rare. Analysis of the current literature produces few case studies that report successful outcomes. Delay in diagnosis and treatment may ultimately result in an irreversible neurological deficit. The potential implications of progression are paraplegia and a significant associated morbidity to the fetus if delivered premature. METHODS: Two cases of spinal tuberculosis in pregnancy are reported with description of clinical presentation, neuroradiographic findings and treatment. RESULTS: Both patients made good recoveries after undergoing cesarean section followed by urgent spinal cord decompression and fixation for progression of neurology. On review at 2 years, neither patient had any permanent neurological deficit. Both children suffered no deleterious effects from treatment of the mothers. CONCLUSIONS: A treatment strategy to successfully treat this group of patients is recommended. Although there is a place for both chemotherapeutic and surgical intervention in the treatment of spinal tuberculosis, the authors suggest initiation of treatment with chemotherapy and close neurological monitoring of the patient, unless deterioration in neurological status mandates surgery. Furthermore, the use of steroids for fetal maturation should be used with caution.

Periprosthetic femoral fractures around hip arthroplasty: current concepts in their management.

Peri-prosthetic fractures (PFF) are complex management problems in orthopaedic surgery. Their treatment has evolved with advances in principles of internal fixation and revision hip surgery. Current classification systems look at anatomical location, prosthesis stability and bone quality. Recent evidence highlights the importance of fracture stability in treatment planning, the weaknesses of single plating, the increasing role of long stem revision and also the importance of bone allografts. We present the principles of management of both intra and post-operative PFFs, including surgical techniques and published outcomes.

Targeting bone morphogenetic protein antagonists: in vitro and in vivo evidence of their role in bone metabolism.

BACKGROUND: Bone morphogenetic proteins (BMPs) and their antagonists are involved in fracture healing. Antagonists regulate BMPs by blocking signal transduction or interfering with transcription factors at the nucleus. OBJECTIVE: To examine targeting of BMP antagonists to manipulate osteogenesis. METHODS: An overview of in vitro and in vivo evidence on effects of BMP antagonists on bone metabolism. RESULTS/CONCLUSION: There is in vitro evidence suggesting that overexpression of noggin and gremlin inhibits osteogenic differentiation, markedly decreases alkaline phosphatase (ALP) levels and impedes R-Smad (1/5/8) phosphorylation in murine cell lines. Knockdown of chordin results in a threefold increase in ALP activity in human mesenchymal stem cells. In vivo data shows that inhibition of noggin leads to increased bone regeneration in mice. Noggin and sclerostin can combine in a mutually inhibitory complex, neutralising their individual inhibitory effects. This allows BMP signalling to proceed to osteoinduction. We highlight the potential for clinical enhancement of bone formation through inhibition of BMP antagonists.