Previous studies have identified clinical and demographic risk factors for recurrence in the treatment of idiopathic clubfoot (congenital talipes equinovarus). Evertor muscle activity is not usually considered amongst them. This study aimed to evaluate whether recurrence could be predicted by demographic, clinical and gait parameters. From a series of 103 children with clubfeet, 67 had completed a follow-up of two years: 41 male and 26 female, 38 with idiopathic and 29 with non-idiopathic deformities. The mean age was 3.2 years (2.1 to 6.3). Primary correction was obtained in all 38 children (100%) with an idiopathic deformity, and in 26 of 29 patients (90%) with a non-idiopathic deformity. Overall, 60 children (90%) complied with the abduction brace regime. At a mean follow-up of 31.4 months (24 to 62), recurrence was noted in six children (15.8%) in the idiopathic and 14 children (48.3%) in the non-idiopathic group. Significant correlation was found between poor evertor activity and recurrence in both groups. No statistically significant relationship was found between the rate of recurrence and the severity of the initial deformity, the age at the time of treatment, the number of casts required or the compliance with the brace.

After correction of idiopathic and non-idiopathic clubfoot using the Ponseti method, only poor evertor muscle activity was statistically associated with recurrence. The identification of risk factors for recurrent deformity allows clinicians to anticipate problems and advocate early additional treatment to improve muscle balance around the ankle.

Cite this article: Bone Joint J 2014;96-B:1264–8.

Cross-shear has been shown to increase ultra-high molecular weight polyethylene (UHMWPE) wear in pin-on-disk, total knee, total hip, and spinal disc replacement testing. Computer modelling of implant wear holds promise for improving efficiency in the development of new implant designs, but it is desirable to accurately account for the effects of cross-shear in the computational simulation. Several studies have sought to propose a quantitative metric for cross-shear in multidirectional sliding and to correlate average cross-shear intensity with apparent wear rate measured in experiments. The apparent wear rate accounts for the total volume loss from all points on the UHMWPE surface. In principle, if the cross-shear metric correlates with experimental wear rates, it is then possible to predict an estimated wear rate for any arbitrary set of kinematic inputs. UHMWPE wear may then be simulated numerically with some form of Archard’s law.

One limitation of the above approach is that counter-face kinematics are homogenized by the use of a spatially and temporally averaged apparent wear rate. In a sliding contact interface of a joint implant in vivo, the intensity of cross-shear wear may vary with time and location on the surface. To address this variation we have proposed a novel cross-shear metric (x*) and developed a modified form of Archard’s law that is capable to differentiate between unidirectional and multidirectional sliding wear. The wear model and x* have been implemented in an explicit finite element framework (ABAQUS) that is capable of quantifying wear from any number of wear surfaces (e.g., front side, backside, post) with completely general geometry and loading conditions.

Preliminary validation of x* and the wear model have been performed by comparison with data from the open literature. Cross-shear metric x* is easy to compute, exhibits invariance to the choice of kinematic reference frame, and is able to reliably distinguish between similarly shaped sliding paths of different lengths – all improvements compared to cross-shear metrics described elsewhere. The wear model that incorporates x* has shown good agreement with pin-on-disk and cervical disc replacement wear results previously reported. Ongoing research focuses on demonstrating similar validity of the model for cross-shear wear in hip and knee replacements.

Introduction: Outcome data is essential for clinical governance and research purposes, and will inform decisions on resource re-distribution. The Spinal Assessment Clinic (SAC) treats patients with low back pain referred by their GPs.

Method: Low Back Outcome Score (LBOS) data was collected at presentation (Q1) for 691 patients and on review (Q2) for 98 patients. At presentation further administrative information is also collected. At review Q2 patient satisfaction is recorded as well as the patient’s perception of the status of their LBP. Results were compared between three clinic locations; inner city (CIT), urban (URB) and semi-rural (RUR).

Results: Significantly more patients at the inner city clinic cancelled and re-appointed, and significantly fewer could be discharged after the first consultation. Equal numbers were employed in the three locations.

Despite failure of improvement of perceived LBP, many patients reported an improvement of LBOS.

Conclusion: Social and environmental factors influence behaviour within a treatment program. Patients can appreciate the difference between a satisfactory treatment experience and an actual change in their low back pain. Function can increase even when reported pain does not.