Design concepts in lumbar total disc arthroplasty

The implantation of lumbar disc prostheses based on different design concepts is widely accepted. This paper reviews currently available literature studies on the biomechanics of TDA in the lumbar spine, and is targeted at the evaluation of possible relationships between the aims of TDA and the geometrical, mechanical and material properties of the various available disc prostheses. Both theoretical and experimental studies were analyzed, by a PUBMED search (performed in February 2007, revised in January 2008), focusing on single level TDA. Both semi-constrained and unconstrained lumbar discs seem to be able to restore nearly physiological IAR locations and ROM values. However, both increased and decreased ROM was stated in some papers, unrelated to the clinical outcome. Segmental lordosis alterations after TDA were reported in most cases, for both constrained and unconstrained disc prostheses. An increase in the load through the facet joints was documented, for both semi-constrained and unconstrained artificial discs, but with some contrasting results. Semi-constrained devices may be able to share a greater part of the load, thus protecting the surrounding biological structure from overloading and possible early degeneration, but may be more susceptible to wear. The next level of development will be the biomechanical integration of compression across the motion segment. All these findings need to be supported by long-term clinical outcome studies.     

骨水泥聚乙烯内衬技术在全髋内衬翻修中的生物力学研究

目的评估骨水泥聚乙烯内衬技术应用于全髋内衬翻修时的生物力学强度。方法 25对金属髋臼及聚乙烯内衬假体随机分为5组(n=5),以标准锁定装置为对照(A组),其余4组应用骨水泥聚乙烯内衬技术固定聚乙烯内衬,分为无钢珠聚乙烯内衬与金属髋臼0°交角组(B组)、带钢珠聚乙烯内衬与金属髋臼0°交角组(C组)、带钢珠聚乙烯内衬与金属髋臼10°交角组(D组)、带钢珠聚乙烯内衬与金属髋臼20°交角组(E组)。通过杠杆试验模拟体内内衬失败情况,测定各组抗杠杆力强度。结果 A～E组抗杠杆力分别为(626.68±206.12)、(915.04±197.49)、(449.02±119.78)、(814.68±53.89)、(1 033.05±226.44)N,组间比较差异有统计学意义(F=8.989,P=0.000)。其中B、E组抗杠杆力大于A组,差异有统计学意义(P<0.05);C、D组抗杠杆力与A组比较,差异无统计学意义(P>0.05)。结论用骨水泥聚乙烯内衬技术将内衬与金属髋臼以≤20°交角固定于金属髋臼内,能提供足够的初始固定强度。     

Revision total hip arthroplasty for metal-on-metal failure

Metal-on-metal (MoM) arthroplasty systems became popular in the early-2000s due to presumed advantages of improved wear characteristics and superior stability. However, subsequent reports of abnormal soft-tissue reactions to MoM implants and national registry data reporting high failure rates raised concerns. Early outcomes of revision total hip arthroplasty (THA) for adverse reaction to metal debris (ARMD) were poor, leading to development of surveillance programs and a trend towards early revision surgery. Patients with MoM arthroplasties require surveillance, comprehensive history and physical examination, imaging with ultrasound or magnetic resonance imaging (MRI), and laboratory evaluation including metal ion levels. Operative strategies for revision THA vary from exchange of modular components to extensive debridement and reconstruction with revision components. Surgeons should be aware of the increased risks of dislocation and infection following revision THA for ARMD. However, there is growing evidence that early revision surgery prior to extensive soft tissue destruction results in improved outcomes and decreased re-operation rates. It is estimated that >1 million MoM articulations have been implanted, with a large proportion still in situ. It is imperative to understand the aetiology, presentation, and management strategies for these patients to optimise their clinical outcomes.     

Conversion total hip arthroplasty: Primary or revision total hip arthroplasty

Total hip arthroplasty (THA) is an increasingly common procedure among elderly individuals. Although conversion THA is currently bundled in a diagnosis related group (DRG) with primary THA, there is a lack of literature supporting this classification and it has yet to be identified whether conversion THA better resembles primary or revision THA. This editorial analyzed the intraoperative and postoperative factors and functional outcomes following conversion THA, primary THA, and revision THA to understand whether the characteristics of conversion THA resemble one procedure or the other, or are possibly somewhere in between. The analysis revealed that conversion THA requires more resources both intraoperatively and postoperatively than primary THA. Furthermore, patients undergoing conversion THA present with poorer functional outcomes in the long run. Patients undergoing conversion THA better resemble revision THA patients than primary THA patients. As such, patients undergoing conversion THA should not be likened to patients undergoing primary THA when determining risk stratification and reimbursement rates. Conversion THA procedures should be planned accordingly with proper anticipation of the greater needs both in the operating room, and for in-patient and follow-up care. We suggest that conversion THA be reclassified in the same DRG with revision THA as opposed to primary THA as a step towards better allocation of healthcare resources for conversion hip arthroplasties.     

Prevalence of heterotopic ossification after cervical total disc arthroplasty: a meta-analysis

Background  

Heterotopic ossification (HO) is a well-known complication after total hip and knee arthroplasty. But limited studies have focused on prevalence of HO following cervical total disc arthroplasty (CTDA) and the published data show controversial results.     

Revision total knee arthroplasty for excessive ligamentotaxis

Correction of varus/valgus deformity via soft tissue balancing is the accepted technique in knee arthroplasty surgery. However, in rare instances, excessive ligamentotaxis can result in overly stretched periarticular structures leading to pain and impaired function. This has been called the "joint jack phenomenon." We report a case in which a very thick polyethylene insert resulted in a painful knee and leg length discrepancy. Our solution was to use a salvage hinge knee arthroplasty to achieve joint space reduction, restore equal leg lengths, and avoid global instability. We believe this is the first report of a surgical reduction procedure to address this specific clinical problem.     

Revision total hip arthroplasty with cemented femoral component

We reviewed retrospectively the results of 28 hips (25 patients) after revision of the femoral component with use of a cemented stem, because of aseptic loosening. The mean duration of follow-up was 4.43 years (range 2–12 years). Over the course of the study period, repeat revision was done in 4 hips after an average of 4.45 years. Three hips had a repeat revision of the femoral component because of aseptic loosening and one for a deep infection. The rate of loosening of the femoral component was 32.4% (9 hips) at an average of 5.22 years. The 5-year survival rate was 76.9% with mechanical failure as end point; and 90% with re-revision of femoral component because of aseptic loosening as end point. The cement mantle was the principal factor, which was significantly associated with a better survival rate of femur fixation (P < 0.05). No correlation was noted between quality of bone loss at the time of revision, bone graft or the use of long stems, and the survival rate of femoral component. By improving the cementing technique and in selected patients, the use of cemented femoral stem could be a good alternative for aseptic loosening THA.     

Revision knee arthroplasty with a rotating-hinge design in elderly patients with instability following total knee arthroplasty

Background

Revision knee arthroplasty with a rotating-hinge design could be an option for the treatment of instability following total knee arthroplasty (TKA) in elderly patients.

Purpose

To evaluate the clinical and radiographic results of revision arthroplasties in TKAs with instability using a rotating-hinge design in elderly patients.

Methods

We retrospectively reviewed 96 rotating-hinge arthroplasties. The average age of the patients was 79 years (range, 75–86 years); the minimum follow-up was 5 years (mean, 7.3 years; range, 5–10 years). Patients were evaluated clinically (Knee Society score) and radiographically (position of prosthetic components, signs of loosening, bone loss).

Results

At a minimum followup of 5 years (mean, 7.3 years; range, 5–10 years), Knee Society pain scores improved from 37 preoperatively to 79 postoperatively, and function scores improved from 34 to 53. ROM improved on average from −15° of extension and 80° of flexion before surgery to −5° of extension and 120° of flexion at the last followup (p = 0.03). No loosening of implants was observed. Nonprogressive radiolucent lines were identified around the femoral and tibial components in 2 knees. One patient required reoperation because of a periprosthetic infection.

Conclusions

Revision arthroplasty with a rotating-hinge design provided substantial improvement in function and a reduction in pain in elderly patients with instability following TKA.

Level of evidence

Level IV, therapeutic study.     

Revision hip arthroplasty prosthesis: a study implant stability

Revision total hip replacement has high rates of failure, which appear to be due in part to deficient bone stock that does not provide an adequate environment for implant fixation. We reviewed the clinical outcomes and implant stability following total hip revisions using the S-ROM implant. Between 1996 to 2001, we performed 62 cementless revision hip arthroplasties using the S-ROM prosthesis. Data on 54 patients were available for study, with a mean follow-up of 4.5 years (range, 4–6 years). Radiological analysis, patient satisfaction and Harris hip scores were assessed pre- and postoperatively. Overall, 85% of patients were satisfied with the results of surgery. Harris hip scores improved from a preoperative value of 40 to 80 points at the last available follow-up. 52 stems (96%) were radiologically stable on the final follow-up. Two had marked initial subsidence, but this later stabilised. There was no re-revision due to loosening. With improvement of the postoperative hip score by more than 40 points and absence of definite implant instability and re-revision at the final follow-up, the use of S-ROM prosthesis in the revision cases of this study seems to have been successful.     

Dual-mobility components obviate the need for constrained components in revision total hip arthroplasty–Affirms

Dual-mobility hip components provide an additional articular surface, with the goals of improving range of motion and overall stability. In many European centers, these components are used for primary total hip arthroplasty. However, their greatest utility may be to prevent and treat recurrent dislocation after revision total hip arthroplasty. Several retrospective series have shown satisfactory results for this indication at medium-term follow-up. There are important concerns with these components, including intraprosthetic dislocation and polyethylene wear causing chronic dislocation, but these are rare phenomena. At present, dual-mobility components are the preferred solution to manage recurrent dislocation in revision surgery.     

Motion preservation following total lumbar disc replacement at the lumbosacral junction: a prospective long-term clinical and radiographic investigation

Background Context

Total lumbar disc replacement (TDR) intends to avoid fusion-related negative side effects by means of motion preservation. Despite their widespread use, the adequate quality and quantity of motion, as well as the correlation between radiographic data with the patient's clinical symptomatology, remains to be established. Long-term data are lacking in particular.

Convertible implants: Simplifying the revision from anatomic total shoulder arthroplasty to reverse total shoulder arthroplasty

Modern shoulder arthroplasty techniques include hemiarthroplasty, total shoulder arthroplasty (TSA), and reverse shoulder arthroplasty (RSA). Out of all arthroplasty procedures, total shoulder arthroplasty produces more satisfactory outcomes for osteoarthritis and inflammatory arthropathy (Sanchez-Sotelo, 2011 [1]). As shoulder arthroplasty procedures continue to increase in popularity, so do revision surgeries (revision TSAs and revision RSAs). Implants used in shoulder arthroplasty procedures have been transformed substantially from generation to generation, going from 1st to 4th generation implants. We propose 5th generation convertible implants that enable a more patient-specific, anatomic reconstruction with the potential to solve major issues that exist with implants from previous years.     

Dual mobility cups in total hip arthroplasty

Total hip arthroplasty (THA) is considered one of the most successful surgical procedures in orthopaedics. With the increase in the number of THAs performed in the world in the next decades, reducing or preventing medical and mechanical complications such as post-operative THA instability will be of paramount importance, particularly in an emerging health care environment based on quality control and patient outcome. Dual mobility acetabular component (also known as unconstrained tripolar implant) was introduced in France at the end of the 1970s as an alternative to standard sockets, to reduce the risk of THA dislocation in patients undergoing primary THA in France. Dual mobility cups have recently gained wider attention in the United States as an alternative option in the prevention and treatment of instability in both primary and revision THA and offer the benefit of increased stability without compromising clinical outcomes and implant longevity. In this article, we review the use of dual mobility cup in total hip arthroplasty in terms of its history, biomechanics, outcomes and complications based on more than 20 years of medical literature.     

Results of different surgical procedures on total knee arthroplasty infections

Seventy-six consecutive infected total knee arthroplasties in 74 patients were treated between December 1981 and March 1990. The average follow-up period was 57 months (range, 24–121 months). No patients were lost to follow-up evaluation and 12 patients died from unrelated causes. Patients were classified, based on the duration of their symptoms prior to treatment, as acutely infected (< 2 weeks) or chronically infected (> 2 weeks). All knees were evaluated following surgical treatment with radiographs and Knee Society knee score assessment. Successful eradication of infection was defined as a knee without clinical evidence of infection for a minimum of 2 years. The initial treatment modality was successful in eliminating the infection in 69 of 76 patients (90%). Infection was eventually eradicated in 72 of 76 (94%) patients. The individual clinical result was found to be more dependent on a patient's medical and musculoskeletal status (patient class A, B, C) than on knee score or radiographic assessment. Careful treatment selection based on patient class and duration of infection can result in a predictable and successful result.     

Revision total hip arthroplasty for pelvic osteolysis with well-fixed cementless cup

Treatment of pelvic osteolysis after total hip arthroplasty (THA) remains controversial. Clinical and radiographic outcomes of revision THA were evaluated in 62 hips with pelvic osteolysis and well-fixed cementless cups. The patients' mean age was 50.9 years, and the mean interval from primary to revision THA was 9.7 years. For revision, cementless cups were used in 51 hips, and cemented cups in 11 with acetabular reinforcement rings in 9. The mean duration of follow-up after revision THA was 5.9 years (range, 3.0-9.7 years). At final follow-up, the average Harris Hip Score was 92.4, and there was no radiographic complication except for 1 with change of inclination. Revision THA for pelvic osteolysis with well-fixed cementless cups showed favorable outcomes, and it can be preferentially used in young patients.     

Revision surgery for patellar dislocation after primary total knee arthroplasty

This study evaluated risk factors for patellar dislocation after primary total knee arthroplasty and determined functional outcomes in patients following revision. Thirty-nine knees in 39 patients averaging 68 years (range, 27-91 years) at the time of revision were evaluated at a mean of 3.2 years (range, 2-7 years). Mean Knee Society and Function scores significantly improved from 34 and 35 to 77 and 54, respectively. Patellar dislocation most commonly resulted from errors in technique such as soft-tissue imbalance and malaligned components that led to poor tracking of the patella. Patellar tracking only improved after soft-tissue realignment in combination with revision of malaligned or loose components. Although revision significantly improved active knee extension and Knee Scores, two thirds of the patients had residual disabilities and pain.     

Revision total hip arthroplasty with an uncemented primary stem in 79 patients

INTRODUCTION: Revision in THA continues to be a technical challenge because of difficulties in fixation of the femoral component in mostly deficient bone in the proximal femur. In cases with minor cortical defects, the use of primary stems in revision surgery has also been described by some authors. MATERIALS AND METHODS: Seventy-nine patients with minor femoral bone defects were reviewed retrospectively (mean follow-up 6.8 +/- 3.9 years), who underwent a femoral component revision surgery using the uncemented primary Bicontact stem (Aesculap, Tuttlingen, Germany). Furthermore, the radiographs (anteroposterior and lateral) before, after surgery and at latest follow-up were analysed concerning femoral defects, proximal bone loss, and to determine the quality of bony fixation. RESULTS: The average Harris hip score (HHS) was 42.2 +/- 20.8 preoperative and improved to 78.9 +/- 12.5 at latest follow-up (p < 0.001). Motion Score increased significantly from 2.7 +/- 1.9 to 3.5 +/- 1.4 (p < 0.05) and pain score decreased significantly from 5.7 +/- 2.9 to 3.6 +/- 2.4 (p = 0.005). During follow-up there were only four re-revisions within 2 years after revision. The results and clinical outcome of this study correspond to those published before, using primary cementless stems in cases of revision. CONCLUSION: Therefore, the primary uncemented Bicontact stem appears to be a good alternative to other revision systems in well-selected femoral revision cases with minor defects.