Faculty Bibliography

Metal hypersensitivity (MHS) is a rare complication of total joint arthroplasty that has been linked to prosthetic device failure when other potential causes have been ruled out. The purpose of this review was to conduct an analysis of existing literature in order to get a better understanding of the pathophysiology, presentation, diagnosis, and management of MHS. It has been described as a type IV hypersensitivity reaction to the metals comprising prosthetic implants, often nickel and cobalt-chromium. Patients suffering from this condition have reported periprosthetic joint pain and swelling as well as cutaneous, eczematous dermatitis. There is no standard for diagnosis MHS, but tests such as patch testing and lymphocyte transformation testing have demonstrated utility, among others. Treatment options that have demonstrated success include administration of steroids and revision surgery, in which the existing metal implant is replaced with one of less allergenic materials. Moreover, the definitive resolution of symptoms has most commonly required revision surgery with the use of different implants. However, more studies are needed in order to understand the complexity of this subject.

Introduction/UNASSIGNED:The rotating hinge prosthesis was originally used and designed as a primary total knee arthroplasty implant, but was hampered due to poor outcomes and catastrophic failures. Newer rotating hinge implants can be utilized in complex revision total knee arthroplasties when appropriately indicated, but their outcome data is very difficult to interpret due to the strict and varied indications for use and subsequently small number of procedures performed. The goal of this review is to evaluate the current evidence on large cohort, rotating hinge knee prostheses used in the revision setting, in order to provide a clearer understanding of the indications, outcomes and complications. Methods/UNASSIGNED:The PubMed database was utilized to search the available literature regarding "hinged knee," or "rotating hinge" devices. Exclusion criteria included papers focusing on primary arthroplasty, revision for oncologic issues, one-stage revision for infection or studies with less than fifty cases. Results/UNASSIGNED:Review of 115 abstracts after initial search, led to ten studies in the literature that met our inclusion and exclusion criteria. The data shows that rotating hinge knee implants have good survivorship ranging from 51% to 92.5% at 10 years post-operatively. Complication rates range from 9.2% to 63% with infection and aseptic loosening as the most common complications. Conclusion/UNASSIGNED:Rotating hinge knee prostheses are most commonly indicated for infection, aseptic loosening, instability and bone loss in the literature. They have good outcome scores and survivorship, but continue to have high complication and revision rates. The implant is a good option when utilized appropriately for patients that are not candidates for less constrained devices.

Paget's disease of the bone is a chronic osteopathy that leads to structural weakness, hypervascularity, and bone deformities. Rapid bone turnover in patients with Paget's disease may affect outcomes following total hip arthroplasty (THA). Most literature on THA in the setting of Paget's disease is limited to isolated case reports or case series documenting a single institution experience. By completing a comprehensive analysis of the available cases, this study aims to investigate the outcomes and complications of THA in patients with Paget's disease.

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.

Periprosthetic distal femoral fractures can present significant reconstructive challenges when associated with poor bone stock, comminution, or component loosening. Revision arthroplasty with stemmed components or distal femoral replacement arthroplasty often becomes necessary. This retrospective study reviewed the results of femoral revision arthroplasty in 16 knees with acute, extreme distal (Su type 3), supracondylar periprosthetic fractures using cemented, midlevel constrained implants. The mean patient age was 71 years and mean follow-up was 5 years. All fractures united with mean Knee Society scores of 86 and 55, at the last follow-up. All patients returned to preinjury activity level. Complications included one valgus malunion with shortening and one reoperation for functional lateral instability. This treatment modality achieved reliable fracture union and return of function. Moreover, the final salvage option of distal femoral arthroplasty is preserved.

There are limited data on the influence of a reduced tourniquet time strategy on the clinical outcome of primary total knee arthroplasty (TKA). The aim of our study was to prospectively compare clinical recovery in two groups of patients undergoing TKA based on differences in tourniquet strategy at the same institution. Group A (40 patients) consisted of TKAs performed by a surgeon using tourniquet from incision to arthrotomy closure, and group B (40 patients) consisted of TKAs performed by another surgeon using tourniquet only during cementation. The surgical technique, implants, perioperative management, and patient demographics were similar between groups. Average tourniquet time was significantly higher in group A (71.7 minutes) as compared with group B (36.8 minutes). The maximum hemoglobin (Hb)/hematocrit (Hct) drop was statistically higher in group B (Hb drop = 3.5 +/- 0.9 g/dL; Hct drop = 11 +/- 3) as compared with group A (Hb drop = 2.9 +/- 0.9 g/dL; Hct drop = 9 +/- 2; Hb drop p = 0.01; Hct drop p = 0.002). There were no significant differences in visual analogue scale pain scores, narcotic consumption, ability to straight leg raise during hospital stay, range of motion (ROM) at discharge, as well as isometric quadriceps strength, ROM, Short Form 36 scores, Knee Society scores at 6 weeks, 3 months, and 1 year follow-up with a similar multimodal pain management protocol. Radiographic analysis revealed no differences in cement penetration around the tibial component in any zone. Four patients developed pulmonary embolism (three in group A, one in group B) and five patients underwent manipulation under anesthesia for stiffness (four in group A, one in group B). Thus, the use of a tourniquet only during cementing in TKA increases the hemoglobin drop and does not significantly influence pain or clinical recovery with available numbers, but was associated with a lower incidence of early complications. It is a learned surgical skill which significantly reduces tourniquet time and achieves a similar quality of cementing.

Patient-specific instrumentation (PSI) in total knee arthroplasty (TKA) has been introduced to obtain consistent alignment, prevent instrumentation of the medullary canal and improve operating room efficiency. This article compares simultaneous bilateral TKA performed with and without the use of PSI in terms of surgical time; blood loss and transfusion requirements; length-of-stay, early thromboembolic events and complication rates. There was a trend to reduced total blood loss (as measured by drop in hemoglobin values) and lower transfusion rate after surgery. Further research in the form of high quality randomized trials and cost-benefit analyses may help in further consolidation of these findings.

The use of tapered, fluted, modular, distally fixing stems has increased in femoral revision surgery. The goal of this retrospective study was to assess mid-term to long-term outcomes of this implant. Seventy-one hips in 70 patients with a mean age of 69years were followed for an average of 10years. Preoperative HHS averaged 50 and improved to 87 postoperatively. Seventy-nine percent hips had Paprosky type 3A or more bone-loss. All stems osseointegrated distally (100%). Two hips subsided >5mm but achieved secondary stability. Sixty-eight percent hips had evidence of bony reconstitution and 21% demonstrated diaphyseal stress-shielding. One stem fractured near its modular junction and was revised with a mechanical failure rate of 1.4%. Distal fixation and clinical improvement were reproducibly achieved with this stem design.