The aim of this study was to establish the ability of an invasive fibre-optic probe to measure intra-muscular pH, pCO₂, pO₂, HCO₃-⁻, ambient temperature, base excess and O₂ saturation. The secondary aim was to determine the effect of elevation of the limb on these parameters.

Fibre-optic probes were introduced into the anterior compartment muscle of the leg in five volunteers via 16G cannulae. After equilibration the limb was monitored for 11min with the volunteer supine on an examination couch. The limb was elevated to 22cm (Braun frame) and then 44cm for the same time. Subsequently the leg was returned to 22cm and supine. All volunteers followed this set protocol. Continuous recording of all indices was made throughout. Data was stored to a personal computer for analysis.

Similar trends were observed across all subjects for all parameters. The mean pO₂ when lying flat was 27mmHg (S.D.7.4). Elevation to 22cm increased muscle pO₂ to 33 mmHg (S.D. 5.8). Further elevation to 44 cm resulted in a reduction in muscle pO₂ to a level below that measured when supine. When the limb was returned to 22cm the pO2 trend reversed, the level improving. Returning to the supine position the pO₂ returned to the level seen at the start of monitoring.

This novel probe gives reproducible measures of pH, pCO₂, pO₂, HCO₃⁻, ambient temperature, base excess and O₂ saturation. Results indicate that elevation to 22cm improves muscle oxygenation; a height of 44cm seems detrimental. This technique may be applicable in surveillance for compartment syndromes and muscle ischaemia.

Arthroscopic acromioplasty is said to be a difficult procedure to learn although Gartsman stated that most surgeons can reliably perform an arthroscopic decompression after instruction in 10–20 cases. We assessed the learning curve for one consultant surgeon.Patients were selected on the basis of clinical examination and all had signs of impingement at arthroscopy. Surgery was performed between February 1993 and June 1996. Patients with full thickness tears were excluded from the study. The senior author had not performed any arthroscopic acromioplasties prior to providing a service in this hospital. Each shoulder was assessed immediately prior to surgery and at follow up using the Constant and Murley method of functional assessment without the power component. Patients were asked if they would have the operation again, with the benefit of hindsight.Of 89 shoulders complete preoperative and postoperative scoring beyond 6 months was available in 71. Of these, 62 operations were performed by one consultant (ANS) and 9 by trainees under his guidance. Patient questionnaires were completed for 73 of 89 shoulders.

A standard operative technique under general anaesthesia was used for all patients.

The overall improvement in shoulder function was 10.3 (SD 12.4) points (p< 0.0001). The change in shoulder score did not vary with increasing surgical experience. The length of operation, however, shortened with increasing experience with a mean of 106 minutes and 60 minutes for the first and last five operations. Questionnaire analysis found 82% would have the operation again.

In our study operative time reached a plateau after approximately the first twenty five cases but the results of these early operations are good.

An innovative Kirschner (K-) wire point was developed and compared in fresh pig femora in terms of drilling efficiency and temperature elevation with the trochar and diamond points currently used in clinical practice. The tips of thermal couples were machined to the defined geometry and the temperature measured during drilling. Using the same drill speed (rev/min) and feed rate, the new K-wire point produced the lowest thrust force and torque as measured by a Kistler dynamometer. Drill point temperatures were highest with the trochar geometry (129 ± 6°C), followed by the diamond (98 ± 7°C). The lowest temperatures were recorded with the Medin K-wire (66 ± 2°C). On repeated drilling it could be used for up to 30 holes before reaching the less satisfactory drill performance of the diamond tip. The new K-wire provides a better alternative as it requires less effort for insertion, generates less heat and may be re-used.