SPONGY METAL LUBECK HIP PROSTHESES FOR OSTEOARTHRITIS SECONDARY TO HIP-DYSPLASIA

Between May 1987 and December 1990, 66 hips in 59 patients with osteoa rthritis secondary to hip dysplasia underwent cementless total hip art hroplasty with a spongy metal Lubeck hip prosthesis (S+G Implants, Lub eck, Germany) that had a fully porous-surfaced short stem made of cast ed cobalt-chrome-molybdenum alloy. Sixty-five hips in 58 patients were prospectively followed for 2-6 years (mean, 43 months). Patient age a t operation ranged from 29 to 63 years (mean, 51 years). The Merle d'A ubigne hip score improved from 7.8 before surgery to 16.9 at the final followup evaluation. Air hips were rated as either excellent (63%) or good (37%). Mild thigh pain was recognized in only three hips (5%) at 6 months after surgery, but it disappeared within 2 years. Serial roe ntgenograms showed stable fixation with bone ingrowth in all hips, tha t is, bone densification in contact with the implant and trabecular co nnection to the endosteal surface. The authors found no migration of t he implant or circumferential radiolucency. Moderate osteopenia, presu mably due to stress shielding, was seen in only four hips (6%). Acetab ular bone-grafting performed in 31 hips gave. successful support to th e socket. Cancellous bone chips grafted to small defects showed excell ent remodeling. The authors conclude that the spongy metal Lubeck hip prosthesis contributed to lower rates of thigh pain and migration than cementless prostheses.