Can Chiari Osteotomy Favorably Influence Long-term Hip Degradation in Multiple Epiphyseal Dysplasia and Pseudoachondroplasia?

BACKGROUND: Multiple epiphyseal dysplasia (MED) and pseudoachondroplasia (PSACH) are congenital skeletal disorders characterized by irregular epiphyses, mild or severe short stature and early-onset osteoarthritis which frequently affect the hips. The current study evaluates the long-term results of the Chiari osteotomy in MED and PSACH patients. METHODS: Twenty patients (14 MED and 6 PSACH) were retrospectively included. Clinical assessment used the Postel Merle d'Aubigné (PMA) score and the Hip disability and Osteoarthritis Outcome Score (HOOS). Risser index, Sharp angle, acetabular depth index, center-edge angle, Tönnis angle, and femoral head coverage were measured on the preoperative radiographs and at last follow-up. The Treble index, which identifies the hip at risk in MED patients, was also determined. Stulberg classification (grades I to V) was used to evaluate the risk of osteoarthritis in the mature hips.Statistical analyses determined differences between preoperative and postoperative data. The Kaplan Meier method was used to calculate the survival rate of the operated hips using total hip arthroplasty as the endpoint. RESULTS: Thirty-three hips which underwent a Chiari osteotomy were reviewed. The average follow-up was 20.1 years. The PMA scores were significantly better at last follow-up than preoperatively. All radiographic parameters significantly improved. Moreover, the Sharp angle, center-edge angle, and femoral head coverage improved to a normal value at hip maturity. All of the operated hips had a Treble index of type I. At hip maturity, a majority of hip were aspherical congruent (Stulberg grades of III and IV). The survival rate of the operated hips was 80.7% at 24 years postoperative. CONCLUSIONS: The Chiari osteotomy is a satisfying solution for severe symptomatic hip lesions in MED and PSACH patients. At long-term follow-up, this procedure lessens pain and improves hip function, which delays total hip arthroplasty indication. LEVEL OF EVIDENCE: Level IV.

Joint contact areas after radial head arthroplasty: a comparative study of 3 prostheses.

BACKGROUND: Contact stresses of radial head prostheses remain a concern, potentially leading to early capitellar cartilage wear and erosion. In particular, point contact or edge loading could have a detrimental effect. The purpose of this study was to compare 3 different types of radial head prostheses in terms of joint contact areas with each other and with the native situation. The hypothesis was that the joint contact areas would be lower after monopolar arthroplasty. METHODS: Seven fresh-frozen cadaveric upper limbs were used. Radiocapitellar contact areas of a monopolar design, a straight-neck bipolar design, and an angled-neck bipolar design were compared with each other and with the native joint. After standardized preparation, polysiloxane was injected into the loaded radiocapitellar joint to create a cast from which the joint contact area was measured. Measurements were performed at 3 angles of elbow flexion and in 3 different forearm positions. RESULTS: In the native elbow, contact areas were highest in supination. Elbow flexion had no significant effect on native and prosthetic joint contact areas. Contact areas were decreased for all types of arthroplasties compared with the native joint (from 11% to 53%). No significant contact area difference was found between the 3 designs. However, bipolar prostheses showed lateral subluxation in neutral forearm rotation, resulting in a significant decrease in the contact areas from pronation to the neutral position. CONCLUSIONS: All types of radial head prostheses tested showed a significant decrease in radiocapitellar contact area compared with the native joint. Bipolar designs led to subluxation of the radial head, further decreasing radiocapitellar contact.

Effects of humeral shortening on the three-dimensional configuration of the brachial plexus: a cadaveric study.

This study reports the gains in length of nerves after three different humeral shortenings. Ten brachial plexuses were dissected. The lengths of the different parts of the brachial plexus were measured using a three-dimensional digitizing system after humeral shaft shortenings of 2, 4 and 6 cm and after a standardized force of 0.588 N was used to apply tension to the plexus. The feasibility of nerve suturing was studied. Humeral shortening allowed for significant gains in lengths of the musculocutaneous (42 mm), median (41 mm), ulnar (29 mm) and radial nerves (15 mm). A 2 cm humeral shortening allowed a 2 cm nerve gap to be directly sutured in 70% to 90% of cases. This study suggests that humeral shortening could allow direct suture of nerve defects, or shorten the length of nerve grafts required to bridge a gap.

The effect of humerus diaphyseal shortening on brachial plexus tension: a cadaver study.

PURPOSE: To assess the extent to which diaphyseal shortening of the humerus can allow direct suture in case of rupture or transection injuries of the brachial plexus. METHODS: The use of 3 fresh cadaver specimens allowed for the study of 6 brachial plexuses. Distance measurements were made between reference points placed on the clavicle and on different parts of the plexus. Those measurements were repeated after shortening the humerus by 2, 4, and 6 cm. RESULTS: None of the dissected plexuses had classic anatomy. A humeral shortening of 6 cm allowed for a statistically significant reduction of length between the supraclavicular part of the plexus and the terminal branches, which did not exceed 17 mm on average. The difference of length was much greater for the specimen in which the musculocutaneous nerve did not pierce the coracobrachialis muscle proximally. CONCLUSIONS: In clinical situations, nerve defects are usually larger than the gain observed when doing a 6-cm humeral shortening. Moreover, this procedure implies a large dissection, a functional loss of certain muscles, and a risk of humeral nonunion. CLINICAL RELEVANCE: In the absence of extensive nerve dissection, the observed change of length is insufficient in the most brachial plexus disruptions to allow for a direct suture instead of long nerve grafts.