Gerald A. B. Saunders

Hemiarthroplasty in the Treatment of Hallux Rigidus

Background: Osteoarthritis of the first metatarsophalangeal (MTP) joint is a painful, disabling condition. It can interfere with the ability to run and even walk without pain. An implant of cobalt-chrome steel alloy to replace the base of the proximal phalanx is one solution. The purpose of this study is to review our results with one of these implants. Materials and Methods: A series of 23 cases of hemiarthroplasty for the treatment of hallux rigidus from June 2000 to October 2001 has been evaluated using the AOFAS rating system, and the results are presented. Results: The average preoperative AOFAS score was 57 (range, 39 to 80). The AOFAS score after hemiarthroplasty was 88 (range, 75 to 100) at last followup (34 to 72 months). There were no perioperative complications except for a small hematoma. Only one patient has required further surgery after 3 years for worsening of a preexisting tendency to hallux valgus. Conclusion: A hemiarthroplasty retained, in most cases, joint mobility, strength, and alignment while relieving pain. There was no evidence, at last followup, of component loosening or osteolysis.

The development of a surface arthroplasty for the elbow.

Complex kinematics, anatomical features, and load distribution have contributed to the poor function of constrained and semiconstrained cemented arthroplasties of the elbow. Resurfacing by porouscoated components has the potential, by reproduction of normal joint geometry and restoration of ligament balance, to recreate relatively normal kinematics and load-bearing and provide relief of pain. A method was developed to provide information on the geometry of the lower humeral joint surface and olecranon fossa. The information gained was used to design components to resurface the trochlea, capitellum, and olecranon fossa. A technique was also developed to remove a minimal amount of subchondral bone from the ulna and humerus in a precisely directed fashion for exact fit of the porouscoated components.

Knee analyser: an objective method of evaluating mediolateral stability in the knee.

A machine is described which is capable of accurately determining the mechanical behaviour of the knee as it undergoes mediolateral bending under controlled conditions. This knee analyser applies a constant valgus and varus angular deflection rate to the knee up to a preset moment limit. The applied moment is sensed by a strain-gauged pillar and the angular deflection by a precision potentiometer. The resulting voltages are fed to an xy recorder yielding a plot of moment against angle. By monitoring distraction of the joint concurrently, the deformation characteristics of ligament and cartilage components can be evaluated. The machine should assist in the diagnosis of knee problems, follow-up of patients with rheumatoid arthritis, evaluation of operative procedures on the knee and should also provide fundamental information on the properties necessary for future knee replacements.

Application of Bench-Mounted Saws for Precision Replacement Arthroplasty of the Arthritic Knee — The Questor Systems

Prosthetic replacement arthroplasty has revolutionised surgical treatment for arthritis of hip and knee joints, but as time passes, the number of failures, (mainly) due to loosening of the implant, increases. Although poor design and material features have a recognised importance in loosening, a malpositioned prosthesis must carry the greatest responsibility [1–4]. The precision involved in the manufacturing process of the implant is set to a level of tolerance ±0. 2 mm. This is, in all likelihood, a factor of over ten times greater precision than current bone cutting/placement techniques. The geometric accuracy employed in the construction of the implants sets a standard to be emulated in the orientation and accurate placement of the prosthesis; it recommends a comparably high level of placemealignment accuracy for the bone cuts.