Abstract
The purpose of the study was to analyse the clinical and radiological results of cementless HAP-coated Mallory- Head hip replacement in dysplastic hips. The collective included 20 males and 30 females (64 hips), with a mean age of 52.6 (range 20–68) years at operation. We also included two patients (4 hips) with spondyloepiphy-seal dysplasia (dwarfism). All patients were operated by one surgeon (EvL) during the period 1991–1997. A majority had “champaign flute” type femur. A minority had a normal or “stove pipe” type femur (Dörr). Most patients had acetabular dysplasia classified as A or B (Eftekar); some were classified as C and one as D (after Schanz osteotomy). Previous operations included: derotating varous osteotomy (11), acetabular shelf plasty (9), Salter or Chiari pelvic osteotomy (4) and tenotomy of the hip adductors (2).
After a mean follow-up of 57 (range 32 to 97) months, a clinical and radiological analysis was performed by an independent investigator (TG). Postoperatively no or only mild pain was reported by 89% of all patients. The VAS for pain (0–10) was excellent: 1.70 (0–7). Limping was reported in 23% and 75% used no support when walking. The HHS increased from 42 to 90 points.
Complications were marginal and there were no infections. One patient developed habitual dislocation and a revision of the cup was perfomed. We saw two periprosthetic fractures of the femur: once during surgery (treated conservatively) and once after a fall (treated by plating). We saw one case of temporary ischiadical nerve palsy after leg lenghtening of 5 cm. There were two cases in which we had used 32mm heads, and PE-wear necessitated revision of the cup after seven and eight years follow-up, respectively.
Cortical hypertrophy indicating stress transfer was found in 28% and located mostly on the borders of Gruen-zones 2, 3 and 5, 6. This cortical hypertrophy (“ballooning”) started to appear after 0.5 to 1 year and did not disappear after a longer follow up. Endosteal spotwelds were infrequently seen (9%) and in 13% of all patients we saw some form of halo- or shelf-formation at the distal stem. The criteria of Enghs fixation scale are not signs of loosening in the Mallory-Head HAP-coated femoral prosthesis.
No radiolucent or radiodense lines were seen around the acetabular cup. In all cases but one (Schanz osteotomy) the anatomical centre of rotation could be restored.
We conclude that the cementless Mallory-Head HAPcoated femoral prosthesis has shown, up to present time, excellent clinical and radiological results in hip dysplasia.
The abstracts were prepared by David P. Davlin. Correspondence should be addressed to him at the Orthopedic Clinic Bulovka, Budínova 2, 18081 Prague 8, Czech Republic.
