[Design considerations for improving the acetabular cup of the ESKA hip endoprosthesis by using the ceramic/ceramic wear couple]. / Konzeptionelle Uberlegungen zur Verbesserung der Pfanne der ESKA-Hüftendoprothese durch die Gleitpaarung Keramik/Keramik.

Since 1987, cementless THR acetabular components with coarsely reticulate surfaces (S&G, ESKA) have been implanted in the Department of Orthopaedic Surgery of the Alfried Krupp Hospital in Essen. By 31st December 1995, 590 of these components had been implanted. Follow-up of the first 51 of these completely cement free THRs revealed loosening in an only single case (2%). Despite these good medium-term results, however, it must be expected that over a ten-year period, the life of the THR will decrease, the probable reason being increasing debris caused by polyethylene (PE) wear leading to aseptic loosening. An alternative to the PE/ceramic system of opposing materials would be ceramic/ceramic. Experience to date has shown that the biological inertness of ceramic does not allow ingrowth and bony integration to take place. Against this background an acetabular component employing a metal backing with the 3-dimensional reticulate surface mentioned above and a Biolox ceramic cup insert articulating with a Biolox ceramic femoral head was designed. The result is a cement free modular THR with optimal bony integration properties and articulating surfaces. To investigate the superiority of this new concept, a comparative study involving two groups of 50 patients each, one group receiving the PE/ceramic system, the other the new ceramic/ceramic system, has been initiated.

[Prevention of heterotopic ossification by radiotherapy following total hip prosthesis]. / Verhinderung ektoper Ossifikationen nach Totalendoprothese des Hüftgelenks durch Strahlentherapie.

BACKGROUND: Clinically relevant heterotopic bone formation (HBF) following total hip arthroplasty (THA) occurs in about one third of all high risk patients. HBF can reduce the functional result of surgery by pain and limited range of motion. The experience with patients treated with postoperative radiation therapy after THA with or without removal of HBF is reported. PATIENTS AND METHOD: Between November 1986 und June 1993, postoperative irradiation was performed on 238 hips of 216 patients (117 men, 99 women, median age 66 years, range 38-86 years) with defined risk factors using 10 Gy in 5 fractions (n = 176) or 7 Gy in one fraction (n = 62) with a cobalt unit. In general, irradiation was performed during the first four postoperative days after primary THA alone in 182 hips or removal of HTB in 56 hips with (n = 28) or without (n = 28) revision surgery. Risk factors for HBF were preexisting ipsi- or contralateral HBF in 105 hips (group 1) or hypertrophic osteoarthritis, previous operative procedures of the hip and others in 134 hips (group 2). After a follow-up of at least 6 months patients were examined and radiographs of the hip were performed to classify HBF. RESULTS: New or progressive ossifications had developed in the interval in 15 of 104 hips of group 1 (14.4%), compared with 19 of 134 hips in group 2 (14.2%). Clinically significant new HBF (grade 3 or 4) occurred in none of group 2, and in 3 hips of group 1 (2.9%). After radiation with 10 Gy HBF of all grades occurred in 23 of 176 hips (13.1%), and in nine of 62 hips after 7 Gy (14.5%). The lowest number of treatment failures was found in patients irradiated during the first 4 postoperative days. CONCLUSION: These results demonstrate that immediate postoperative radiation is efficacious for prevention of clinically relevant HBF following THA and removal of HBF.

Evidence for lysosomotropism of memantine in cultured human cells: cellular kinetics and effects of memantine on phospholipid content and composition, membrane fluidity and beta-adrenergic transmission.

Memantine, an amantadine derivative, is therapeutically used for the treatment of various neurological and psychiatric disorders such as Parkinson's disease, spasticity, and dementia. Pharmacokinetics of memantine and its effects on phospholipid content and composition, on membrane properties and functions such as fluidity and beta-adrenergic transmission were studied in cultured human fibroblasts and macrophages. The kinetic behaviour of memantine was characteristic for a lysosomotropic drug. Fibroblasts exposed to 14C-memantine in the microM range accumulated the drug up to 200 fold above initial medium concentrations. Lysosomal drug storage was proven by indirect evidence and by analyses of subcellular fractions. Repetitive exposure to memantine resulted in a cumulative uptake. While memantine uptake after single exposure was fully reversible, the rate and extent of release of chronically accumulated drug was reduced but could be enhanced by the addition of unlabelled memantine or ammonium chloride to the medium. Chronic, but not single, exposure to memantine above 10 microM resulted in a concentration dependent phospholipid accumulation and in a shift in the phospholipid composition. There was an overproportionate increase in phosphatidylinositol at the expense of phosphatidylserine and sphingomyelin. Chronic exposure of cultured cells to memantine increased fluidity in the superficial layers of the plasma membrane and reduced the isoproterenol-stimulated cAMP-response without affecting beta-adrenoceptor density. All these findings were compatible with the kinetic behaviour and the effectiveness expected of a weak lysosomotropic drug.

Impingement of the rotator cuff in athletes caused by instability of the shoulder joint.

An impingement of the rotator cuff can be caused by chronic anterior instability of the shoulder joint. This particular disease is often found in athletes engaged in overhead motion in abduction/external rotation of the arm, such as in ball sports like volleyball or European handball, racket sports like tennis or badminton, or swimming. For those patients that cannot be cured by conservative treatment such as muscular stabilization, surgical treatment is indicated: anterior reconstruction of the capsule and/or the glenoid labrum, and in addition--if necessary--subacromial decompression and revision of the rotator cuff. Between October 1988 and April 1992, we operated on 66 shoulders in 64 top athletes suffering from chronic anterior or multidirectional instability of the shoulder joint that had caused an impingement syndrome of the rotator cuff. In all cases, the athlete was unaware of the instability. Conservative treatment had been unsuccessful. Surgical treatment was successful in close to 90% of the athletes.