Michel Malo

The unstable patella after total knee arthroplasty: etiology, prevention, and management.

Abstract In total knee arthroplasty, most complications related to the extensor mechanism are caused by patellar maltracking or instability. Patellar maltracking may result from component malpositioning and limb malalignment, prosthetic design, improper patellar preparation, or soft‐tissue imbalance. Patellofemoral instability likely results most frequently from internal malrotation of the femoral or tibial components. Although a patellofemoral radiograph may display the lateral subluxation of the patella, only computed tomography can quantify rotational malalignment of the femoral or tibial component. Nonsurgical treatment is generally unsuccessful; major malposition of components is best managed by implant revision. In the absence of component malposition, proximal realignments (lateral patellar retinacular release with lateral advancement of the vastus medialis obliquus muscle) or tibial tubercle transfers have been used. Surgical procedures on the patellar tendon itself may risk rupture of the extensor mechanism.

Functional evaluation in distal femoral endoprosthetic replacement for bone sarcoma

A multicenter study of successfully treated patients (mean age, 36.7 years) with a minimum 1-year followup (average, 35.4 months) after distal femoral endoprosthetic replacement for bone sarcoma was done using the 1987 and 1993 versions of the Musculoskeletal Tumor Society, the Short Form-36, and the Toronto Extremity Salvage Score functional evaluation criteria. Fifty-six patients (28 women and 28 men) fulfilled the criteria. Thirty-one Kotz prostheses (fixed hinge, uncemented) and 25 Modular Replacement System Prostheses (rotating hinge, cemented) were used. Thirty-five patients walked without aids, 19 used a cane, and two used crutches or a walker. The Musculoskeletal Tumor Society 1987 mean score was 28.1. The Musculoskeletal Tumor Society 1993 mean score was 80.4. The Toronto Extremity Salvage Score mean was 81.6. The Short Form-36 Physical Component Score had a mean of 43.2 and Mental Component Score mean of 54.2. The two groups of implants were comparable, except for the length of bone resection. Multivariate regression analysis revealed that patient age, existence of a pathologic fracture, and type of prosthesis all significantly accounted for differences in functional outcome as measured by the Musculoskeletal Tumor Society 1993, the Toronto Extremity Salvage Score, and the Short Form-36 Physical Component Score scales. Although both implants provided satisfactory function, the Musculoskeletal Tumor Society 1993 and the Toronto Extremity Salvage Score results were significantly better with the Modular Replacement System prosthesis. The effect of possible differences among surgeons or institutions was not addressed.

Treatment of large bone defects with trabecular metal cones in revision total knee arthroplasty: short term clinical and radiographic outcomes.

The early term results of 29 cases of revision total knee arthroplasty using highly porous trabecular metal cone implants for femoral and tibial major bone deficit reconstruction (Anderson Orthopedic Research Institute classification type 2B and 3) have been prospectively analyzed. Indications for revision surgery included: aseptic loosening/wear, staged reimplantation after infection, as well as periprosthetic fracture. At an average follow-up of 33 months (range, 13-73 months) the mean Knee Society Score and functional score statistically improved. Radiological follow-up revealed no evidence of loosening or migration of the constructs. No evidence of complications was noted in correlation with the use of trabecular metal cones. This study supports evidence that trabecular metal cones are an efficient and effective option for dealing with significant bone deficits and obtaining stable biological fixation in revision total knee arthroplasty.

Elucidating the Role of Protandim and 6-Gingerol in Protection Against Osteoarthritis

Protandim and 6‐gingerol, two potent nutraceuticals, have been shown to decrease free radicals production through enhancing endogenous antioxidant enzymes. In this study, we evaluated the effects of these products on the expression of different factors involved in osteoarthritis (OA) process. Human OA chondrocytes were treated with 1 ng/ml IL‐1β in the presence or absence of protandim (0–10 μg/ml) or 6‐gingerol (0–10 μM). OA was induced surgically in mice by destabilization of the medial meniscus (DMM). The animals were treated weekly with an intraarticular injection of 10 μl of vehicle or protandim (10 μg/ml) for 8 weeks. Sham‐operated mice served as controls. In vitro, we demonstrated that protandim and 6‐gingerol preserve cell viability and mitochondrial metabolism and prevented 4‐hydroxynonenal (HNE)‐induced cell mortality. They activated Nrf2 transcription factor, abolished IL‐1β‐induced NO, PGE2, MMP‐13, and HNE production as well as IL‐β‐induced GSTA4‐4 down‐regulation. Nrf2 overexpression reduced IL‐1β‐induced HNE and MMP‐13 as well as IL‐1β‐induced GSTA4‐4 down‐regulation. Nrf2 knockdown following siRNA transfection abolished protandim protection against oxidative stress and catabolism. The activation of MAPK and NF‐κB by IL‐1β was not affected by 6‐gingerol. In vivo, we observed that Nrf2 and GSTA4‐4 expression was significantly lower in OA cartilage from humans and mice compared to normal controls. Interestingly, protandim administration reduced OA score in DMM mice. Altogether, our data indicate that protandim and 6‐gingerol are essential in preserving cartilage and abolishing a number of factors known to be involved in OA pathogenesis. J. Cell. Biochem. 118: 1003–1013, 2017.

Incidence of symptomatic venous thromboembolism in 2372 knee and hip replacement patients after discharge: data from a thromboprophylaxis registry in Montreal, Canada

Background Low-molecular-weight heparin (LMWH) is a recommended anticoagulant for thromboprophylaxis after major orthopedic surgery. Dabigatran etexilate is an oral anticoagulant recognized as noninferior to LMWH. We aimed to assess the incidence of symptomatic venous thromboembolic events (VTEs) after discharge in patients who underwent joint replacement, using a hospital registry. Patients and methods Patients who underwent total knee and hip arthroplasty between September 2011 and March 2015 were selected. Subcutaneous enoxaparin (30 mg twice daily) was given during hospitalization. At discharge, patients received either enoxaparin 30 mg twice daily/40 mg once daily or dabigatran 220 mg/150 mg once daily. Patients were seen or called at 2, 6, and 12 weeks after surgery. Outcomes were the number of VTEs, including deep venous thrombosis, pulmonary embolism, and the number of major/minor bleeding events after discharge. Results After discharge, 1468 patients were prescribed enoxaparin and 904 dabigatran (1396 total knee arthroplasty and 976 total hip arthroplasty patients). Mean age was 66±10 years, and 60% were female. The cumulative incidence of VTEs during the 12-week follow-up was 0.7%. One patient sustained a VTE during the switch window. Seven patients sustained a pulmonary embolism (0.3%). There was no statistical difference between the total knee arthroplasty and total hip arthroplasty groups. The incidence of major and minor bleeding events during follow-up was 0.3% and 30.3%, respectively. These events had a higher incidence in the dabigatran group compared to the enoxaparin group after discharge (p<0.05), but not between knee and hip replacement groups for major bleeding events. Conclusion A pharmaceutical prophylaxis protocol using LMWH and dabigatran during the post-discharge period resulted in low incidences of VTE and equivalence between treatments. However, the increased number of major and minor bleeding events in patients taking dabigatran is of concern regarding the safety and needs to be evaluated using analyses adjusted for risk factors.

Managing Patella Defects

It is well known that patella resurfacing has its limits. Severe patella bone loss can occur in the primary knee where significant patella bone loss can make it difficult to perform a patella resurfacing. While the ultimate limit as to the smallest amount of residual bone will allow a patella resurfacing to be performed, it is commonly believed that at least 12 mm is needed to avoid complications of resurfacing.

Severe heterotopic ossification and stiffness after revision knee surgery for a periprosthetic fracture

Although heterotopic ossification (HO) after total hip arthroplasty has been very well described as a cause of disability, much less was written on clinical dysfunction of HO after total knee arthroplasty (TKA). To the extent of our knowledge, there has been no published case of complete bony ankylosis, secondary to severe generalized HO, after a TKA. We present the case of a 67-year-old female treated successfully, with surgical excision of ossification and TKA revision surgery, using a rotating hinge system.