Faculty Bibliography

PURPOSE/OBJECTIVE:There has been an increase in the use of unlinked constrained condylar knee (CCK) prostheses in primary total knee arthroplasty (TKA) for cases with significant deformities that cannot be adequately balanced in flexion and extension. However, the literature on its outcomes is limited. The goal of this study is to evaluate whether there are any clinic or radiographic outcome differences for a primary, non-stemmed, unlinked constrained TKA as compared to a control group of posterior-stabilized (PS) TKA using the same implant design. METHODS:Clinical and radiographic outcome measures for 404 cemented, non-stemmed, primary TKAs performed by two surgeons at the same institution were retrospectively reviewed. All patients underwent primary, non-stemmed components; 241 used CCK inserts and 163 used PS inserts. Preoperative deformity, knee society scores (KSS), range-of-motion (ROM), radiographic data and revision rates were compared between the CCK and PS groups. RESULTS:Both groups had comparable demographics and preoperative ROM and KSS. At similar mean follow-up times (6.1 ± 1.0 years for the CCK group and 6.3 ± 1.2 years for the PS group), no significant difference was found in ROM, KSS or radiographic outcomes. Revision rates were higher for the CCK group (2%) as compared to the HF-PS (0.6%) group (n.s). CONCLUSIONS:The particular design of cemented, primary, non-stemmed, unlinked CCK-TKA examined in this study provided similar clinical and radiographic outcomes to that of PS-TKA at midterm follow-up. LEVEL OF EVIDENCE/METHODS:III.

BACKGROUND:Short-stem (SS) hip prostheses for total hip arthroplasty (THA) have gained popularity as surgeons strive to reproduce physiological stress distributions at the proximal femur. Additionally, as THA indications continue to target younger populations, preservation of femoral bone stock for potential revision surgeries is particularly appealing. However, little is known regarding the short-term complications of each variety of short stem during the learning curve period. The purpose of this study is to evaluate the short-term complications among the THA recipients with the use of a novel SS hip prosthesis. METHODS:A retrospective chart review was performed of all patients undergoing primary THA utilizing an Echo Bi-Metric Microplasty hip stem. Patient demographics, surgical factors, complications and quality outcomes were collected utilizing our institution's data warehouse and verified by chart review. RESULTS:In total, 182 SSs were implanted in 168 patients undergoing primary THA. Of these, 5 (2.9%) patients sustained a periprosthetic fracture. Two fractures occurred during the index hospital admission, and 3 occurred in the post-discharge period. Subset analysis demonstrated that 4 (80%) fractures had occurred during the initial learning curve period, within the first 30 surgical cases with a SS. CONCLUSION/CONCLUSIONS:Short-stem hip prostheses are a safe alternative for THA. The results of the present study demonstrate a fracture incidence of 2.9% among patients. However, surgeons should remain cautious when utilizing new implant system and expect a learning curve. In this study, 80% of periprosthetic fractures following SS THA occurred within the first 30 cases for experienced arthroplasty-trained surgeons.

Total joint arthroplasty of the hip and knee are successful orthopedic procedures that reduce pain and improve mobility in patients. As the implanted materials used in these procedures have improved, the lifetime of the implants has now reached more than 20 years. Younger patients are undergoing total joint arthroplasty at increasing rates, which has increased the need for improvements in materials for extended implant longevity. In this review, we aim to provide historical perspective on the evolution of ultra-high-molecular-weight polyethylene in total joint arthroplasty. We review this material with respect to its structure, mechanical properties, wear rates, sterilization effects, crosslinking, and other new polymer innovations. Ultra-high-molecular-weight polyethylene (UHMWPE) has been a cornerstone for total joint arthroplasty and with continued design improvements will continue to be vital to this successful orthopedic operation.

With the aging population and rising incidence of primary total joint arthroplasty has come the increasing incidence of revision total hip arthroplasties. One challenge in revision total hip arthroplasty is dealing with acetabular defects. The orthopaedic surgeon who chooses to take on these challenges requires a proper method for the evaluation of these defects as well as an evidence-based treatment algorithm. Initial assessment requires appropriate use and interpretation of imaging modalities such as x-rays and computed tomography. Preoperative planning presupposes knowledge of available approaches and implant options, such as porous coated jumbo cups, modular augments, and cup-cage constructs. Surgical execution necessitates experience in the indications for each type of implant for various types of defects. This review will aid in the understanding of each step of the diagnosis and treatment of acetabular defects in revision total hip arthroplasty.

PURPOSE: The use of unlinked constrained condylar components (CCK) has been extended to primary total knee arthroplasty (TKA); however, there is limited literature on its outcomes. The purpose of this retrospective cohort study was to assess clinical outcomes of one particular design of primary, non-stemmed, unlinked constrained TKA and to compare them with a control group of PS-TKA utilizing the same implant design. METHODS: The clinical and radiographic outcomes of 486-cemented, non-stemmed, primary TKA's performed by two surgeons at one institution using similar surgical algorithm, technique and prosthetic design were retrospectively reviewed. Primary TKA components were used in all knees; the only difference between groups was the type of polyethylene inserts used (CCK vs PS). Pre-operative deformity, knee society scores (KSS), range-of-motion (ROM), radiographic data and revision rates were compared. RESULTS: Both groups had comparable demographics, pre-operative coronal plane alignment, ROM and KSS. At a mean follow-up of 3.5 years, no difference was found in ROM, KSS, radiographic outcomes and revision rates. CONCLUSIONS: Cemented, primary, non-stemmed CCK-TKA offered comparable clinico-radiographic results to PS-TKA at short-term follow-up. Use of a semi-constrained insert without additional stems did not predispose to failure due to aseptic loosening with this implant design. Moreover, the rate of revision due to instability was lowered. LEVEL OF EVIDENCE: Retrospective cohort study, Level III.

Revision of metal-on-metal (MoM) total hip arthroplasty (THA) or hip resurfacing is associated with high complication rates. The authors propose dual-mobility components as a surgical option and present short- to mid-term results of MoM hips revised with dual-mobility components. Eighteen consecutive hips that underwent revision of MoM THA or hip resurfacing using dual-mobility components were identified. At final follow-up (mean, 17.5 months), the visual analog scale, modified Harris Hip Score, and SF-12 scores had all improved (P<.05, P<.01, and P<.05, respectively). There were no dislocations or other complications. Revision of failed MoM THA or hip resurfacing using a dual-mobility device is an effective strategy. [Orthopedics. 2015; 38(6):369-374.].

Periprosthetic fractures of the femur after total hip replacement can present some unique challenges to the treating reconstructive orthopedic surgeon. Treatment may differ depending on fracture location, bone condition, implant stability, patient characteristics, and surgeon experience. It is imperative that adequate and sufficient mechanical fixation be achieved in the treatment of these patients. It is crucial that the treating orthopaedic surgeon have a clear and effective treatment plan to manage these complex cases. The patient's final outcome is dependent on fracture union, implant stability, early functional recovery, and return to pre-injury independence. This review presents an overview of the current diagnostic and treatment approaches, with the goal of providing a template for optimal decision-making when dealing with these complex injuries.

Insufficiency fractures present a significant problem in patients with osteoporosis. We report a case of bilateral iliac wing insufficiency fracture following low energy injury in an 87-year-old osteoporotic woman occurring 2 weeks after primary total hip arthroplasty. There are only a few reports of insufficiency fractures involving the ilium in the literature, and diagnosis has proven challenging, as radiographs are often negative at symptom onset. Magnetic resonance or radionuclide imaging is generally necessary for definitive diagnosis. This case highlights the importance of careful perioperative management of patients with osteoporosis.

PURPOSE: Rotating hinge knee prostheses are known to provide inherent stability. Yoke fractures of the hinged tibial insert of modern generation rotating hinge devices are a matter of continued concern. The aim of this study was to describe incidence and management of yoke fracture of the LPS hinged tibial insert. METHODS: Retrospective data analysis of two institutions identified 40 patients with a LPS total knee arthroplasty. Implant survival and prosthetic complications was calculated according to Kaplan-Meier. RESULTS: Out of the group of 40 patients, four fractures of the metal yoke occurred in four cases (failure rate: 10%). Furthermore, a second fracture occurred in two patients. The overall revision-free prosthetic survival was 57% at 38 months, while prosthetic survival until yoke fracture was 86% at 38 months. CONCLUSION: Handling yoke fractures as mechanical complication includes replacing the hinged insert, stabilization of the joint and joint line height preservation in order to decrease the cantilever effect at the insert-base plate interface.

There has been a steady increase in the number of revision total knee arthroplasties being performed in the United States. Hinge knee prostheses are used predominantly in complex primary or revision arthroplasties, often as salvage procedures. Significant improvement of the articulation between the rotating hinge mechanism and tibial component has decreased the stresses that contributed to earlier failures in previous generation designs. Two cases of fracture of the tibial metal post in the rotating hinge of a revision total knee arthroplasty were evaluated and treated at our institution within a 1-month period. We present our experience with this construct failure and subsequent patient management