The Pronator Quadratus (PQ) is commonly damaged in the surgical approach to the distal radius during volar plating. This study explored the functional strength of the PQ muscle, 12 months after volar plating of a distal radial fracture.

Testing of treated and contralateral forearms was carried out using a custom-made Torque Measuring Device (TMD) and surface Electromyography (sEMG). To assess both the direct and indirect function of PQ in participants treated with volar plating and compared to the contralateral non-injured forearms. The angle of elbow flexion was varied from 45o, 90o and 135o when measuring forearm pronation. Mean peak torque of the major pronating muscles, PQ and Pronator Teres (PT) was directly measured with the TMD and the indirect activation of the PQ and PT was measured with sEMG.

In total 27 participants were studied. A statistically significant reduction in mean peak pronation torque was observed in the volar plated forearms (P<0.05 SE 0.015, CI 95%). This is unlikely to be of clinical significance as the mean reduction was small (13.43Nm treated v 13.48Nm none treated). Pairwise comparison found no statistically significant reduction in peak torque between 45o, 90o and 135o of elbow flexion. There was an increase in PQ muscle activation at 135o compared to 45o elbow flexion. The converse was identified in PT.

The small but statistically significant difference in mean peak torque in treated and uninjured forearms is unlikely to be of clinical significance and results suggest adequate functional recovery of the PQ after volar plating.

MTPJ instability is very common yet there is no consensus of best surgical technique to repair it. The current techniques range from extensive release, K-wire fixation or plantar plate repair, which requires release of remaining intact plantar plate and all collaterals. Such varieties reflect a controversy regarding its aetiology. The aim of this study was to assess how much each structure contributes towards the stability of MTPJ and describing a simple technique designed by the senior author that can anatomically reconstruct all contributing structures to the pathology.

Eleven cadaveric toes in two groups (five in group 1 and six in group 2) were included. Dorsal displacement (drawer test) was used to measure instability in an intact MTPJ followed by two different series of sequential sectioning of each part of collateral ligament (PCL and ACL) and part or complete plantar plate.

Group 1 result showed that after incising PCL dorsal displacement was 0.51mm, PCL+ACL was 0.8mm and PCL+ACL+50% plantar plate was 2.39mm. Group 2 results showed that after incising 50% plantar plate dorsal displacement was 0.48mm, after full plantar plate 0.62mm, plantar plate +PCL was 0.74mm and plantar plate +PCL+ACL was 1.06mm.

To produce significant instability, both collaterals on one side with combination of 50% plantar plate tear was needed. An isolated 50% tear of plantar plate caused less displacement of MTPJ compared to isolated collaterals. PCL contributed more towards the stability of MTPJ when the plantar plate was intact. Whereas, ACL contributed more stability when plantar plate was sectioned. The current practice of releasing the collaterals to gain access for repairing plantar plate by indirect method should be re-evaluated. A new technique of proximal tenotomy of extensor digitorum brevis tendon looped around the transverse ligament and attached to the neck of metatarsal reconstructs both structures (plantar plate and collaterals).

Growth rods are currently used in young children to hold a scoliosis until the spine has reached a mature length. Only partial deformity correction is achieved upon implantation, and secondary surgeries are required at 6-12 month intervals to lengthen the holding rod as the child grows. This process contains, rather than corrects, the deformity and spinal fusion is required at maturity. This treatment has a significant negative impact on the bio-psychosocial development of the child.

Introduction: Total hip replacement is a commonly performed surgical procedure with at least 50,000 operations taking place each year in Britain The Swedish Hip Registry quotes a success rate of 94.6% at 10years, decreasing with time. The major reason for failure of the total hip replacement is aseptic loosening of the femoral stem, which accounts for 75.7% of revision. Polymethylmethacrylate cement is used in THR, unlike glues, which form a chemically adhesive bond, cement forms a mechanical bond with bone. In order to maximize the strength of this mechanical bond, an optimum interlock between the cement and the irregular, lattice-like, structure of the cancellous bone must be achieved. Current surgical methods to insert the stem into the bone cavity are purely manual; it is proposed to increase the amount of cement penetration by using a vibration technique.

Materials and Methods: A model was developed to approximate the conditions under which a cemented THR would be performed. The model consisted of a Zimmer Collarless Polished Tapered size 1 stem and a reusable mould, designed to simulate the femoral cavity into which a cemented stem would be inserted. This was then used to compare the cement micro-interlock induced under normal and mechanically vibrated conditions. To impart mechanical vibration to the stem of the prosthesis during insertion into the cement filled mould a custom built device was employed. PMMA cement was mixed and inserted into the mould according to the manufacturer’s instructions. The stem was then lowered into the cement mantle. The cement was allowed 10minutes to cure, the mould was then separated and the cement mantle retrieved and removed from the prosthesis stem. The resulting cast had dimples across the surface that corresponded to the holes in the mould. These dimples were then counted and classified into one of four categories, formed, semi-formed, unformed and voids. Two variables were studied, frequency and amplitude. All other known variables were controlled or monitored.

Results: The frequency and amplitude of vibrations at which optimum interlock was achieved in this test was at 19Hz and 4mm.The maximum force needed to insert a stem without vibration was found to be approximately equal to 185N, the same test was performed when the stem was vibrated during insertion, and the force was found approximately equal to 125N.

Conclusion: The results found indicate that vibration of the femoral stem during insertion into PMMA cement has a beneficial effect on the cement-bone interface. An increase in the frequency of formed and semi-formed dots with the use of vibration has been noted. Another effect of vibrating the prosthesis as it is inserted into the cement is to significantly lower the force needed for insertion by about 50N at an insertion depth of 100mm. This is a considerable force, roughly the weight of a gallon of water. Evidence presented here and from previous studies suggests mechanical vibration of an implant during cemented joint replacement has a beneficial effect on the cement bone interface.