Early failure of a mobile-bearing unicompartmental knee replacement.

Concerned by a perceived high revision rate, we retrospectively reviewed the survivorship of a series of 43 cemented, medial, mobile-bearing Preservation unicompartmental knee replacements implanted during a 2-year period at a single institution. The initial post-operative AP and lateral radiographs were independently assessed to test the hypothesis that suboptimal implantation of the prosthesis was responsible for early failure. An X-ray scoring system based on the criteria for assessing the Oxford mobile-bearing unicompartmental knee replacement was devised. The components of this score included assessment of prosthesis alignment, sizing and cementation. Nine (21%) LCS Preservation mobile-bearings prostheses had required revision at a mean of 22 months post-implantation. The commonest causes for failure were pain (44%) and tibial component loosening (33%). Analysis of post-operative radiographs showed no difference (n.s.) between the compound error scores for the revised and the surviving prostheses. No particular surgical error was identifiable leading to subsequent need for revision. The high failure rates shown in this study have led us to cease using this implant. The clinical relevance of this study is that the captive running track of the LCS mobile-bearing prosthesis may over constrain the meniscal component leading to early failure.

The relationship between gastro-oesophageal reflux symptoms and achalasia.

BACKGROUND AND AIMS: Patients with achalasia can experience heartburn, which may be misinterpreted as gastro-oesophageal reflux disease (GORD), leading to a delay in diagnosis and subsequent treatment. We investigated the relationship between gastro-oesophageal reflux (GOR) and reflux symptoms in a large cohort of patients with achalasia. METHODS: The symptoms of all patients with a manometric diagnosis of achalasia made over the past 15 years were studied. The types of treatment, onset and pattern of heartburn, lower oesophageal sphincter pressure (LOSP) and 24-h oesophageal pH studies were compared. RESULTS: A total of 110 out of 225 untreated (48.9%) and 57 out of 99 treated (57.6%) patients experienced heartburn. An oesophageal pH study was performed on 80 patients and GOR was found in only six out of 57 untreated (10.5%) and 10 out of 23 treated (43.5%) patients. A low LOSP (<10 mmHg) was associated with an increased risk of GOR [odds ratio (OR) 14.2; 95% confidence interval (CI) 1.6-128.7; P<0.02). Treated patients were also more likely to develop GOR (OR 7.9; 95% CI 2.0-32.1; P<0.005). Neither the LOSP nor previous treatment was, however, a predictor of heartburn. The timing of the onset of dysphagia and heartburn was categorized in 111 patients. There was no significant difference in mean (or median) LOSP between these three groups, indicating that the LOSP is unlikely to predict the occurrence of symptoms. CONCLUSIONS: Heartburn is common in patients with untreated and treated achalasia, but is a poor predictor of GORD. Such patients should always be investigated with a 24-h oesophageal pH study to clarify the presence of GORD.

Does it really spin? Intra-medullary nailing of segmental tibial fractures--a cadaveric study.

This study aims to quantify the effect of intra-medullary reaming on rotational displacement of both long diaphyseal segmental tibial fractures (Melis Type III) and short (Melis Type IV) in a cadaveric model with differing degrees of soft tissue stripping. Eighteen fresh-frozen cadaveric specimens (9 matched pairs), median age at death was 85 years (68-92) were used to perform a standardized reaming procedure for an intra-medullary tibial nail and the rotational displacement of the segmental fracture fragment (long and short diaphyseal fractures) was recorded. Rotational displacement was recorded using a goniometer and K-wires positioned in the proximal, segmental and distal fracture fragments. Type III fractures rotate more than Type IV fractures (p<0.0001). In Type III fractures reaming to fit with 0%, 50% and 100% soft tissue stripping resulted in rotational displacement of 11.7 SD 12), 13 (SD 16.5) and 307.3 (SD 118.1) degrees respectively. In Type IV fractures reaming to fit with 0%, 50% and 100% soft tissue stripping resulted in rotational displacement of 8.5 (SD 5.5), 12.7 (SD 9.9) and 135.3 (SD 147.1) degrees respectively. The use of a pointed reduction clamp or unicortical plate eliminated rotational displacement. Reaming is a major risk factor for rotational displacement of segmental tibial fractures irrespective of the degree of soft tissue stripping. Long diaphyseal segmental fractures rotate more than shorter segmental fractures. We recommend always clamping the fracture during reaming to avoid rotational displacement.