[Benign cystic bone lesions]. / Benigne zystische Knochenläsionen.

BACKGROUND: Bone cysts are benign tumor-like lesions which often present as a fluid-containing cavity in the bone. They can occur in the skeletal bone as solitary or sometimes multiple bone lesions. OBJECTIVES: This review discusses the diagnostics, radiological appearance and therapeutic strategies of the most important benign cystic bone lesions, such as simple bone cysts, aneurysmal bone cysts, intraosseous ganglia, epidermoid cysts and subchondral cysts. The differential diagnoses with respect to cystoid formations and tumors with cystic components are discussed. METHOD: A selective literature search was performed taking own experiences into consideration. RESULTS: These tumor-like lesions can have the radiological appearance of bone tumors but show no autonomic, stimulus-independent growth and can resolve spontaneously. In the majority of cases open biopsy is necessary to confirm the diagnosis. In some cases no surgical intervention is necessary (e.g. do not touch and leave me alone lesions), whereas in other cases the focus of treatment is on the prevention and therapy of pathological fractures as well as prevention of recurrence. CONCLUSION: Cystic bone formations are among the most commonly occurring non-traumatic bone lesions. To eliminate differential diagnostic unclarity, histological investigation of biopsy material is essential. In terms of surgical intervention there exists a trend towards multimodal therapy mostly based on a meticulous curretage.

Reconstruction of acetabular defects with porous tantalum shells and augments in revision total hip arthroplasty at ten-year follow-up.

AIMS: The use of trabecular metal (TM) shells supported by augments has provided good mid-term results after revision total hip arthroplasty (THA) in patients with a bony defect of the acetabulum. The aim of this study was to assess the long-term implant survivorship and radiological and clinical outcomes after acetabular revision using this technique. PATIENTS AND METHODS: Between 2006 and 2010, 60 patients (62 hips) underwent acetabular revision using a combination of a TM shell and augment. A total of 51 patients (53 hips) had complete follow-up at a minimum of seven years and were included in the study. Of these patients, 15 were men (29.4%) and 36 were women (70.6%). Their mean age at the time of revision THA was 64.6 years (28 to 85). Three patients (5.2%) had a Paprosky IIA defect, 13 (24.5%) had a type IIB defect, six (11.3%) had a type IIC defect, 22 (41.5%) had a type IIIA defect, and nine (17%) had a type IIIB defect. Five patients (9.4%) also had pelvic discontinuity. RESULTS: The overall survival of the acetabular component at a mean of ten years postoperatively was 92.5%. Three hips (5.6%) required further revision due to aseptic loosening, and one (1.9%) required revision for infection. Three hips with aseptic loosening failed, due to insufficient screw fixation of the shell in two and pelvic discontinuity in one. The mean Harris Hip Score improved significantly from 55 (35 to 68) preoperatively to 81 points (68 to 99) at the latest follow-up (p < 0.001). CONCLUSION: The reconstruction of acetabular defects with TM shells and augments showed excellent long-term results. Supplementary screw fixation of the shell should be performed in every patient. Alternative techniques should be considered to address pelvic disconinuity. Cite this article: Bone Joint J 2019;101-B:311-316.

Cup-cage reconstruction for severe acetabular bone loss and pelvic discontinuity: Mid-term Results of a Consecutive Series of 35 Cases.

AIMS: Severe acetabular bone loss and pelvic discontinuity (PD) present particular challenges in revision total hip arthroplasty. To deal with such complex situations, cup-cage reconstruction has emerged as an option for treating this situation. We aimed to examine our success in using this technique for these anatomical problems. PATIENTS AND METHODS: We undertook a retrospective, single-centre series of 35 hips in 34 patients (seven male, 27 female) treated with a cup-cage construct using a trabecular metal shell in conjunction with a titanium cage, for severe acetabular bone loss between 2011 and 2015. The mean age at the time of surgery was 70 years (42 to 85) and all patients had an acetabular defect graded as Paprosky Type 2C through to 3B, with 24 hips (69%) having PD. The mean follow-up was 47 months (25 to 84). RESULTS: The cumulative five-year survivorship of the implant with revision for any cause was 89% (95% confidence interval (CI) 72 to 96) with eight hips at risk. No revision was required for aseptic loosening; however, one patient with one hip (3%) required removal of the ischial flange of the cage due to sciatic nerve irritation. Two patients (6%; two hips) suffered from hip dislocation, whereas one patient (one hip) required revision surgery with cement fixation of a dual-mobility acetababular component into a well-fixed cup-cage construct. Two patients (6%; two hips) developed periprosthetic infection. One patient was successfully controlled with a two-stage revision surgery, while the other patient underwent excision arthroplasty due to severe medical comorbidities. For the whole series, the Harris Hip Score significantly improved from a mean of 30 (15 to 51) preoperatively to 71 (40 to 89) at the latest follow-up (p < 0.001). CONCLUSION: Our findings suggest that cup-cage reconstruction is a viable option for major segmental bone defects involving the posterior column and PD. It allows adequate restoration of the acetabulum centre with generally good stability and satisfactory postoperative function. Instability and infection remain drawbacks in these challenging revision cases. Cite this article: Bone Joint J 2018;100-B:1442-48.

Pelvic reconstruction following resection of malignant bone tumours using a stemmed acetabular pedestal cup.

AIMS: Pelvic reconstruction after the resection of a tumour around the acetabulum is a challenging procedure due to the complex anatomy and biomechanics. Several pelvic endoprostheses have been introduced, but the rates of complication remain high. Our aim was to review the use of a stemmed acetabular pedestal cup in the management of these patients. PATIENTS AND METHODS: The study involved 48 patients who underwent periacetabular reconstruction using a stemmed pedestal cup (Schoellner cup; Zimmer Biomet Inc., Warsaw, Indiana) between 2000 and 2013. The indications for treatment included a primary bone tumour in 27 patients and metastatic disease in 21 patients. The mean age of the patients at the time of surgery was 52 years (16 to 83). RESULTS: At a median follow-up of 6.6 years (95% confidence interval 4.6 to 8.2), local control was achieved in all patients; 19 patients had died (16 of disease). Complications occurred in 19 patients (40%), of which deep infection was the most common, affecting eight patients (17%). Seven patients (15%) had a dislocation of the hip. Aseptic loosening was found in three patients (6%). Two (4%) underwent hindquarter amputation for non-oncological reasons. The risk of revision, with death being treated as a competing event, was 28% at one year, 39% at five years and 48% at ten years post-operatively. The mean Musculoskeletal Tumour Society Score at final follow-up was 71% (27% to 93%). CONCLUSION: This type of reconstruction is a satisfactory option for the treatment of patients with a periacetabular tumour. There remains, however, a high rate of complication, which may be reduced by future modifications of the device such as silver coating and tripolar articulation. Cite this article: Bone Joint J 2017;99-B:841-8.

Review of the outcomes of complex acetabular reconstructions using a stemmed acetabular pedestal component.

AIM: Until now, there has been no consensus as to whether stemmed acetabular components are appropriate for use in patients undergoing revision total hip arthroplasty (THA) who have major acetabular defects or pelvic discontinuity. We wished to address this deficiency in the literature. PATIENTS AND METHODS: We carried out a retrospective study of 35 patients (six men and 29 women) with a mean age of 68 years (37 to 87), with major acetabular defects who underwent revision THA between 2000 and 2012. RESULTS: At a mean follow-up of 63 months (24 to 141), a total of 15 patients (43%) had required at least one further operation. Six implants (17%) loosened aseptically, four (11%) were further revised for infection and two (6%) for technical failure. By taking revision for any reason as the endpoint, the rate of survival of the implant was 61% after five years; by taking revision for aseptic loosening as the end point, it was 78%. The cumulative five-year survival for aseptic loosening was 94% in patients without pelvic discontinuity, and 56% in those with pelvic discontinuity. CONCLUSION: These results indicate a significantly worse survival in patients with pelvic discontinuity (p = 0.020) and we advise caution in the use of the pedestal component in patients with major acetabular defects and pelvic discontinuity who require revision THA. As a result of these findings we have stopped using this implant and prefer to use particulate bone grafts protected with an anti-protrusion cage and posterior column plate fixation, if necessary. TAKE HOME MESSAGE: Based on these poor results, we advise caution if using the pedestal component in patients with major acetabular defects with the presence of a pelvic discontinuity. Cite this article: Bone Joint J 2016;98-B:772-9.