Long-term results and explant analysis of the ReMotion total wrist arthroplasty.

The ReMotion wrist replacement has good short- to medium-term survival with an acceptable complication profile as we previously reported in a cohort of patients with rheumatoid arthritis. We now report the long-term results of the same cohort and details of explant analysis of revisions undertaken for aseptic loosening. A total of 16 wrists were reviewed. Seven prostheses remain in situ with no obvious signs of wear or radiological loosening at a mean follow-up of 15.5 years. Three wrists had been revised: one for infection and two for aseptic loosening. Five patients (six wrists) died 2-9 years after operation from unrelated causes. Explant analysis demonstrated relatively minor wear compared with the published results of the Universal-2 prosthesis. We hypothesize that this may be explained by differences in polyethylene sterilization and prosthetic design. The ReMotion wrist replacement has favourable long-term results in patients with rheumatoid arthritis with a 16-year survival rate of 78%-86%.Level of evidence: IV.

Length Matters: Short Base-Plate Angle Guides May Lead to Guide-Wire Mal-Positioning When Inserting a DHS. A Radiographic Modeling Study.

The dynamic hip screw (DHS) consists of a barrel-plate fixed to the relatively-straight proximal femoral shaft, and a screw which slides within the barrel at a fixed angle, usually 135°. The guide-wire is inserted using a guide at the set angle. Guide design varies between manufacturers, with some new guides being particularly short. We analysed the impact of guide design on the resulting trajectory of the guidewire, and its potential to cause a surgical error. Twenty AP hip radiographs were analysed. Trauma Cad (Brainlab, Munich, Germany) software was used to template a 4-hole 135° DHS onto the intact femur with the screw positioned in the center of the head. A template of a Stryker (Michigan, USA) 135° DHS guide (37 mm long) was then overlaid at the hip screw entry point, and the set trajectory marked. The divergence between the two trajectories was measured (α angle). The distance the guide would have to be moved inferiorly to attain the correct position in the head was then noted. The median divergence (α angle) caused by the guide relative to the ideal position was 6° (range 2-12). This led to the guidewire placement being a median of 9.1 mm (range 3-23) superior in the head (ß).To achieve the correct position of the wire in the head, the guide needed to be moved inferiorly a median of 8 mm (range 2-10). © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:574-577, 2020.

Simple radiographic assessment of bone quality is associated with loss of surgical fixation in patients with proximal humeral fractures.

AIM: This study aimed to determine if the ratio of cortical thickness to shaft diameter of the humerus, as measured on a simple anterior-posterior shoulder radiograph, is associated with surgical fixation failure. PATIENTS AND METHODS: 64 consecutive fractures in 63 patients (mean age 66.1 years, range 35-90) operated with surgical fixation between March 2011 and July 2014 using PERI-LOC locking plate and screws (Smith and Nephew, UK) were identified. Predictors of bone quality were measured from preoperative radiographs, including ratio of the medial cortex to shaft diameter (medial cortical ratio, MCR). Loss of fixation (displacement, screw cut out, or change in neck-shaft angle >4 degrees) was determined on follow-up radiographs. RESULTS: Loss of fixation occurred in 14 patients (21.9%) during the follow up. Patients were older in the failure group 72.8 vs. 64.2 years (p=0.007). The MCR was significantly lower in patients with failed fixation 0.170 vs 0.202, p=0.019. Loss of fixation is three times more likely in patients with a MCR <0.16 (41% vs. 14%, p=0.015). Increased fracture parts led to increased failure rate (p=0.0005). CONCLUSION: Medial cortex ratio is significantly associated with loss of surgical fixation and may prove to be a useful adjunct for clinical decision making in patients with proximal humeral fractures.

The litigation cost of negligent scaphoid fracture management.

The aims of the study were to quantify the litigation cost of scaphoid mismanagement, identify the main reasons why patients sought compensation and hence provide suggestions for reducing litigation. Data were obtained from the National Health Service Litigation Authority. All orthopaedic-related litigation between 1995 and 2010 in the UK was reviewed. Litigation specifically against mismanagement of scaphoid fractures were identified and grouped according to the plaintiff's complaint. Exclusions were all unsettled claims. There were 85 closed cases of scaphoid fracture mismanagement over 15 years. Reasons for litigation were as follows: seven failures in interpreting radiographs, 57 missed fractures, four fractures not immobilized, nine discharged too early, five delayed operations and three inappropriate surgeries. The mean cost was &OV0556;41 680 per case (range &OV0556;0-&OV0556;206 789), and a cumulative cost of &OV0556;3 542 855. The majority of litigation may relate to a lack of follow-up and may demonstrate a failure of protocol-driven reassessment. Secondary surveys following major trauma are also highly relevant.

Differential distribution of cobalt, chromium, and nickel between whole blood, plasma and urine in patients after metal-on-metal (MoM) hip arthroplasty.

Evidence shows that raised cobalt (Co), chromium (Cr), and nickel (Ni) whole blood concentrations correlate with poor device outcome in patients following metal-on-metal (MoM) hip arthroplasty. To understand the local and systemic pathological effects of these raised metal concentrations it is important to define their distribution between whole blood, plasma, and urine. The metals were measured by Inductively Coupled Plasma Mass Spectrometry (ICPMS). Two hundred and five plasma, 199 whole blood, and 24 sets of urine samples were analyzed from 202 patients with Co-Cr alloy MoM hip prostheses implanted between 8 months to 12 years (mean 6.0 years) prior to analysis. Plasma Co (median 39.1 nmol/L) showed significantly positive 1:1 correlation with whole blood Co (median 45.9 nmol/L; R(2) = 0.98, p < 0.001, slope = 1.0). Plasma Cr (median 53.8 nmol/L) and whole blood Cr (median 40.3 nmol/L) were also correlated; however, concentrations were significantly higher in plasma indicating relatively little blood cell uptake (R(2) = 0.96, p < 0.001, slope = 1.6). Urinary Co was up to threefold higher than Cr (median 334.0 vs. 97.3 nmol/L respectively). Nickel concentrations in whole blood, plasma, and urine were low relative to Co and Cr. The analysis shows fundamental differences in the physiological handling of these metals: Co is distributed approximately equally between blood cells and plasma, whereas Cr is mainly in plasma, despite which, Cr had far less renal excretion than Co.