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: Patellar tendon rupture is rare in the general population. Typically, failure occurs proximally or at the mid-substance. Distal avulsion from the tibial tubercle in adults is rare and not well described in the orthopedic literature. METHODS: We present the largest series of patients with distal patellar tendon injury with associated multi-ligamentous disruption of the knee. A series of six patients with distal patellar tendon avulsion were identified at a single institution. The cases were reviewed and are presented. RESULTS: Each case of distal patellar tendon rupture was associated with high-energy trauma to the knee. There was multi-ligamentous disruption in all cases, associated tibial plateau fracture in one case, and a compartment syndrome diagnosed in another. We propose that distal patellar tendon avulsion is a distinct pathology of the extensor mechanism in healthy adults. When present, it should prompt clinicians to assess patients for occult knee dislocation, monitor their neurovascular status, and obtain an MRI to evaluate for associated multi-ligamentous injury. CONCLUSION: We propose a modification to the Schenk classification to include extensor mechanism injury to help guide steps of operative intervention.

A 67-year-old man presented to orthopaedic care with a painful knee. Workup was consistent with septic arthritis of a native knee, and the patient underwent operative treatment. Cultures from the operating room were speciated to Staphylococcus lugdunensis. To the investigators' knowledge, this is the first reported S. lugdunensis infection in a peripheral joint in the absence of an orthopaedic prosthesis. Although traditionally associated with infectious endocarditis, S. lugdunensis has been identified as a causative agent in many organ systems, including orthopaedic infections. This case report emphasizes the importance of familiarity with this emerging pathogen in the treatment of a septic joint.

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.

Today, patients with human immunodeficiency virus (HIV) live long enough to develop chronic degenerative and HIV-associated joint disease. There is a growing population of patients infected with HIV who are candidates for total hip arthroplasty (THA). A total of 31 HIV-positive, non-hemophilic patients undergoing 41 THAs at our institution between 2000 and 2012 were identified. In-hospital medical complications were reported in 5 of 41 hips, all of which resolved prior to discharge. Deep infection developed in 1 of 41 hips and revision was required in 3 of 41 hips. These results suggest that low rates of complications and revision can be achieved in the HIV-positive, non-hemophilic population. We believe that with careful patient selection, THA may improve the quality of life in the HIV-positive population.

Patellofemoral arthroplasty has been described as an appropriate treatment for isolated patellofemoral arthritis. With the aging population and the increasing number of total joint arthroplasties, both patients and surgeons are on the lookout for alternatives to total joint arthroplasty. With appropriate patient selection, well-designed implants, and precise surgical technique, the outcomes of patellofemoral arthroplasty can be excellent. The main indication for patellofemoral arthroplasty is isolated patellofemoral arthritis.

Wire breakage and migration is a known complication of using a wire tension band construct to treat displaced patella fractures. We report a case of a broken K-wire that migrated from the patella completely into the proximal tibia without complication 9 years after the index surgery. This report highlights the fact that wire migration can occur long after fracture healing and be relatively asymptomatic. But because the complications of wire migration can be deadly, it requires diligence on the part of the physician to educate the patient that new knee pain after operative fixation requires formal evaluation by the treating surgeon.

Metal-on-metal bearing surfaces in total hip arthroplasty have been recently shown to have acceptable survivorship properties (J Bone Joint Surg Am. 2006;88:1183; J Bone Joint Surg Am. 2006;88:1173), and they have certain advantages and disadvantages when compared to conventional metal-on-polyethylene bearing surfaces. Like traditional metal-on-polyethylene bearings, these metal-on-metal implants may also suffer from catastrophic failure. This case report represents an unusual situation in a 57-year-old man in which dissociation of a metal inlay in a metal-on-metal total hip arthroplasty resulted in articulation of the inferior aspect of the inlay with the femoral neck, leading to femoral neck notching, extensive periprosthetic soft tissue metallosis, osteolysis, and subsequent prosthetic catastrophic failure

Three cases of fractured uncemented, fully porous Echelon femoral stems (Smith & Nephew, Memphis, Tenn) are examined. Fracture of these components, an uncommon complication of revision hip surgery, is thought to result from cantilever bending after distal bony ingrowth. The stems in these cases fractured at 11, 22, and 28 months after revision surgery. Risk factors include increased body weight, excessive activity, an undersized stem, varus alignment, inadequate proximal femoral bone stock, and metallurgic defects. Extraction can be difficult and is often accomplished with the use of multiple trephines or via tamping through a distal cortical window