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Establishing the three portals for hip arthroscopy in the correct sequence is crucial, as is use of the image intensifier for location and passage of needles. Patient position for hip arthroscopy can be either lateral decubitus or supine. Gentle techniques are essential to avoid scuffing of the articular surface. The 70 degrees scope is the "workhorse" in this procedure. Location of portals is essential to successful hip arthroscopy.

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The virtual reality arthroscopic knee simulator (VR-AKS) consists of a computer platform, a video display, and two force-feedback (haptic) interfaces which also monitor the position of the instruments in the user's hands. The forces that the user would normally apply to the lower limb during arthroscopy are directed through an instrumented surrogate leg. Proprietary software furnishes the mathematical representation of the physical world and replicates the visual, mechanical, and behavioral aspects of the knee while task-oriented programs monitor and record specific areas of user performance. A prototype has demonstrated the feasibility of the system and work on the first, fully functional simulator will begin soon.

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From 1983 to 1989, 147 unicompartmental knee arthroplasties (UKA) were performed. Eighteen knees (13%) have required revision: there were 11 (37%) Porous Coated Anatomic (PCA), three (8%) Microloc, and four (17%) Fibermesh UKAs. Retrieved implants were examined to determine the pattern and extent of polyethylene wear. Wear was severe in each series and was characterized by delamination, pitting, peripheral cracking, deformation, and abrasion. Polyethylene failure appeared to result from large localized stresses resulting from lack of conformity of the articular geometries of the prostheses. Progressive subluxation of the implants occurred that produced very high localized contact stresses at the periphery of the tibial component where the polyethylene was thinnest. The progression of osteoarthritis in these knees, particularly the attenuation of the anterior cruciate ligament, increased the tendency of these incongruous implants to subluxate. Although changes in the design and manufacturing of unicompartmental knee arthroplasties may increase the resistance of these implants to polyethylene wear, the progression of osteoarthritis at an unpredictable rate is likely to be associated with persistent polyethylene wear in this type of arthroplasty.

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Gastroendoscopic examinations were conducted on 75 Thoroughbred foals aged two to 85 days on seven breeding farms in England and Ireland. The foals showed no signs of gastric disease. There was no significant difference between lesion prevalence in foals in England (16 of 28 foals; 57 per cent) or Ireland (22 of 47 foals; 47 per cent). Neither was there any sex predilection (18 of 36 males; 20 of 39 females). Lesions were most prevalent in foals under 10 days old (8 of 9) and least prevalent in foals older than 70 days (3 of 10). Lesions occurred most frequently in the squamous mucosa immediately adjacent to the margo plicatus along the greater curvature (34 foals), whereas lesions in the squamous fundus, the glandular fundus, and the lesser curvature were observed in 11, six and three foals, respectively. Lesions were not observed in the squamous mucosa surrounding the cardia. Gastric lesions were more prevalent in foals with a previous disorder than in those without (68 vs 43 per cent) and particularly with a history of recent or concurrent diarrhoea (9 of 14).

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Correlation of double contrast arthrotomography (DCAT) of the shoulder and arthroscopic surgery diagnostic results have been undertaken in 55 patients with persistent shoulder pain or involuntary shoulder instability. During the period March 1984 to December 1986, 55 patients underwent DCAT followed by videotaped diagnostic shoulder arthroscopy. The primary indication for DCAT was persistent pain in 36 patients and instability in 17 patients. DCAT was performed according to the method of El-Khoury and Albright, and all arthroscopies were performed in a similar fashion by the senior author (HJS). Both tests were reviewed separately, retrospectively, and their results were correlated. For combined (anterior and posterior) labral pathology, the sensitivity/specificity for the instability group was 0.91/0.91, respectively; sensitivity/specificity for the pain group was 0.63/0.94. DCAT accurately depicted the status of 76% of anterior labrums and 96% of posterior labrums. For complete rotator cuff tears, sensitivity/specificity was 1.0/0.94. The status of a complete rotator cuff tear was accurately depicted in 91% of patients. Partial rotator cuff tears were missed in 83% of patients by DCAT. The presence or absence of loose bodies was accurately represented by 96% of DCAT. Arthroscopy showed that 71% of the instability patients had a labral tear, compared with 44% of the pain patients. Rotator cuff pathology was present in 12% of instability patients and 42% of pain patients. These findings indicate that DCAT may be a conditionally reliable test in the diagnosis of shoulder instability. DCAT must be considered inconclusive, however, in the painful shoulder without instability. Its usefulness as a preoperative screening test is discussed, and a diagnostic algorithm is presented. DCAT does not equal the diagnostic accuracy of shoulder arthroscopy.

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Twenty-nine patients with tibial non-union or delayed union were treated by onlay grafting, using long struts from the ipsilateral fibula and without disturbing the non-union site. Internal fixation and excessive dissection can be avoided. Follow-up in 28 patients showed solid healing in all; 20/28 patients united the fracture within 7 months. Removal of the fibula as a distracting force, combined with the principles of onlay grafting advocated by Phemister, is effective surgical treatment.

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