Breakage of Tapered Junctions of Modular Stems in Revision Total Hip Arthroplasty-High Incidence in a Consecutive Series of a Single Institution.

BACKGROUND: Modularity in revision THA (RTHA) has become accepted during the last three decades. Nevertheless, specific risks of modularity of current revision devices such as breakage of taper junctions occur during follow-up. Data reporting failure rates are predominantly given by the manufacturers but independent data acquisition is missing so far. QUESTIONS/PURPOSES: 1. What time-related risk of breakage of taper junction between neck and body of an established modular revision device can be expected in a consecutive single institutional series and a mid-term follow-up? 2. Are there specific factors influencing breakage in this cohort? MATERIALS AND METHODS: A retrospective analysis was performed of a consecutive series of 89 cases after femoral revision using a tapered modular revision stem. Mean follow-up period was 7.1 (range: 3.0-13.7) years. Breakage of stem as failure criteria of the implant was investigated with a Kaplan-Meier analysis. RESULTS: Breakage of taper junctions occurred in four patients during follow-up showing a time-depending implant survival of 94.2 (95% CI: 88.6-100%) after 13.7 years. Implant survival of stems with lateralized necks of 87.4 (95% CI: 75.6-100%) after 13.7 years was significantly lower compared to the standard offset variant with 100% after 13.5 years (log rank test p = 0.0283). Chi square test also revealed a significantly higher risk of breakage of lateralized necks compared to standard offset pieces (p = 0.0141). Three of four patients were obese with a mean BMI of 37.9 kg/m2. Grade of obesity (grade 1 or higher) had significant influence on risk of breakage. Survival of the implant was significantly lower in obese patients with at least grade 1 obesity compared to patients with a BMI < 30 kg/m2 (82.9 (95% CI: 64.9-100%) after 11.6 years vs. 98.4 (95% CI: 95.3-100%) after 13.7 years; log-rank p = 0.0327). CONCLUSIONS: Cumulative risk for failure of taper junctions was high in this consecutive single institutional cohort and may further increase during follow-up. As independent data acquisition in registries is missing, failure rate may be higher than reported data of the manufacturers. The use of lateralized offset necks in obese patients of at least grade 1 obesity showed a significantly higher risk of breakage. The use of monobloc revision devices may be an option, but randomized control trials are currently missing to establish standardized treatment protocols considering individual risks for both monobloc and/or modular implants.

En-Bloc Resection of Metastases of the Proximal Femur and Reconstruction by Modular Arthroplasty is Not Only Justified in Patients with a Curative Treatment Option-An Observational Study of a Consecutive Series of 45 Patients.

BACKGROUND: There is little conformity regarding the surgical treatment of metastasis of the proximal femur, especially in palliative patients with limited life expectancy. PATIENTS AND METHODS: En-bloc resection of secondary bone malignancies of the proximal femur and reconstruction by modular arthroplasty was performed in a consecutive series of 45 patients. The mean follow-up period was 16.4 months (0.6-74.7). RESULTS: The survival rate of all patients was 6.6% (95% CI: 0-14.9) at 74.7 months. There was no significant difference in patients with a solitary or disseminated disease at index operation (log-rank p = 0.1214). Recurrent dislocation was the most frequent local complication (n = 6) necessitating an open reduction in four cases. The use of a Trevira tube showed a higher risk of dislocation compared to the simple bonding of remaining soft tissue (6 out of 28 vs. 0 out of 17; Fisher test: p = 0.0463). The worst-case survival rate with the removal of the arthroplasty for any cause and/or loss to follow-up was 80.0% (95% CI: 44.9-100) at 74.7 months (n = 1 due to low-grade infection). CONCLUSIONS: En-bloc resection of metastases and reconstruction by modular arthroplasty is reliable even in patients with very limited life expectancy. Local complications due to tumor growth or instability after intralesional surgery could be managed successfully but recurrent dislocation as the most frequent complication has to be taken into account. The simple bonding of remaining soft tissue around the prosthesis without the use of an attachment tube may reduce the dislocation rate and reoperation risk.

Vitamin D Deficiency: The Missing Etiological Factor in the Development of Juvenile Osteochondrosis Dissecans?

BACKGROUND: Vitamin D deficiency can result in rickets and hypocalcemia during infant and childhood growth. There is an increasing interest in the role of vitamin D with regards to childhood bone health. Osteochondrosis dissecans (OD) is a common disease affecting different joints. To date, the exact etiology of OD still remains unclear. The aim of this study was to evaluate a possible association of vitamin D deficiency and juvenile OD. METHODS: A retrospective chart review of the years 2010 to 2015 of all orthopaedic patients with an initial diagnosis of juvenile OD admitted to undergo operative treatment of the OD was performed. Patient demographics, medical history, information on sports activity (if available) and serum vitamin D (25-OH-D) level on admission date were obtained. For statistical comparison, we measured baseline prevalence of vitamin D insufficiency in age-matched orthopaedic patients presenting at the department of pediatric orthopaedics. RESULTS: A total of 80 patients were included in this study. Overall, 97.5% (n=78) of tested patients in the OD group had serum vitamin D levels below the recommended threshold of 30 ng/mL (mean value of 10.1 ng/mL (±6.7 ng/mL)). Over 60% (n=49) were vitamin D deficient, 29 patients (37%) showed serum levels below 10 ng/mL corresponding to a severe vitamin D deficiency. Of note, only 2 patients (2.5%) reached serum vitamin D levels above the recommended threshold of 30 ng/mL. No statistical difference was found in respect to sports activity level before onset of the symptoms (P=0.09). Statistical analysis found a significant difference in vitamin D levels between patients with OD and patients without an OD (P=0.026). CONCLUSIONS: We found an unexpected high prevalence of vitamin D deficiency in juveniles diagnosed with OD presenting with significant lower mean 25-OH-D level compared with a control group. These results suggest that vitamin D deficiency is potentially associated with the development of OD. Thus, vitamin D deficiency might be an important cofactor in the multifactorial development of juvenile OD. For this reason, supplementation of vitamin D might not only be a potential additional therapy but also be a possible preventative factor in patients with juvenile OD. However, future prospective studies are needed to confirm this preliminary data. LEVEL OF EVIDENCE: Level III-this is a case-control study.

Gluteal silicone injections and total hip arthroplasty: a case report.

INTRODUCTION: Silicone injection is a common procedure in cosmetic surgery. Granuloma formation and migration are the most commonly observed complications. CASE PRESENTATION: We report an unusual case of avascular necrosis of the hip in a 41-year-old woman from Thailand presenting with hip pain. Subcutaneous nodules were observed in the clinical examination. A pelvic X-ray revealed necrosis of the right femoral head and histological analysis of the punctuated nodules showed a reaction of foreign body granulomas. During surgical treatment with a hip replacement solitary silicone cysts were removed. CONCLUSIONS: This case report emphasizes that orthopedic surgeons treating patients with necrosis of the hip joint in combination with palpable granulomas in the gluteal region have to be aware of silicone augmentation and its potential complications before planning a hip replacement.

Preferred use of polyhexanide in orthopedic surgery.

In orthopedic and trauma surgery, the most frequently used antiseptic is polyhexanide. Its favored application is based on prepossessing tissue compatibility in contrast to various antiseptics and a high antimicrobiological effect. Recent studies showed toxic effects of this antiseptic on human chondrocytes. The aim of this study was to further analyze the toxic and apoptotic effects of polyhexanide on primary human chondrocytes. The hypothesis of this study was that polyhexanide induces apoptosis on human chondrocytes. Primary human chondrocytes were isolated and cultured from human donors with osteoarthritis of the knee who underwent total arthroplasty and had no indication of infection. Polyhexanide at a standard concentration of 0.04% was added to the monolayer cultures. Early and late apoptotic cells were analyzed by flow cytometric detection of annexin V, active caspases, and 7AAD, and by fluorescence microscopy using annexin V and propidium iodide staining. Flow cytometric analysis demonstrated an increase of annexin V and active caspases expression of human chondrocytes after incubation with polyhexanide. Fluorescence microscopy demonstrated a high number of annexin V positive and propidium iodide negative early apoptotic cells. The data show that polyhexanide promotes apoptosis on primary human chondrocytes in vitro, which may indicate the use of polyhexanide in septic joint surgery.

Do short-stemmed-prostheses induce periprosthetic fractures earlier than standard hip stems? A biomechanical ex-vivo study of two different stem designs.

INTRODUCTION: The causes of periprosthetic fractures of the femur due to the design of the prosthesis and the individual parameters of the patient are unexplored. By different anchorage techniques in cementless total hip arthroplasties, it is assumed that there are various load limits of the implant's bearing femur. MATERIALS AND METHODS: In the present study, we compared a standard hip stem (cementless Spotorno) and a short-stemmed design (Mayo) by an artificial reproduction of periprosthetic fractures in 20 femur specimens. RESULTS: The measured fracture loads showed an extensive range, with higher maximum loads in the standard stem group. The bone mineral density and the subsiding pattern of the standard stems showed a significant correlation to the incidence of the periprosthetic fractures. In the experimental setup, a slightly lower fracture resistance was shown for the short-stemmed prosthesis. Additionally, it was shown that donors with a higher body mass index had a significantly increased fracture risk. CONCLUSIONS: Short-stemmed prostheses, especially the Mayo hip, do not constitute a higher fracture risk. In general, an increased body mass index among patients with a cementless hip stem is associated with an increased fracture risk, particularly at high load values, i.e., resulting from a step during stumbling. Taking into account the ascertained results, the danger of provoking a femoral periprosthetic fracture can be reduced.