Desiderius Sabo

Pattern of Periprosthetic Bone Remodeling Around Stable Uncemented Tapered Hip Stems: A prospective 84-month follow-up study and a Median 156-month Cross-Sectional Study with DXA

Bone resorption in the proximal femur is commonly seen after total hip arthroplasty (THA). With dual energy X-ray absorptiometry (DXA), the amount of bone mass (BMD) after implantation of a total hip stem can be precisely determined. However, prospective evaluation of the change of bone mass around the stem is only available for selected stems and short-term follow-up (up to 36 months). We analyzed BMD in patients who had undergone uncemented THA by DXA. Only patients with good clinical outcome (Merle d’ Aubigné score > 12) were included to obtain normative data for regular bone response. Two separate studies were performed: a prospective longitudinal study over 84 months with baseline values acquired within the first postoperative week (group A) (n = 26 patients) and a separate cross-sectional study, median follow-up 156 (124-178) months (group B) (n = 35 patients). Regions of interest were defined according to Gruen (ROI 1-7) and as net average ROI (net avg) for the periprosthetic femoral bone. After the initial remodeling process (12 months), BMD was compared to the 84-month (longitudinal) and the 156-month (cross-sectional) follow-up values to determine long-term periprosthetic changes of bone mineral density. The longitudinal study (group A), after the initial bone remodeling, showed no relevant further bone loss for women and men with BMD values 1.19 ± 0.15 and 1.40 ± 0.19, respectively, 12 months (women 89.8%, men 93.6%), and 1.19 ± 0.13 and 1.36 ± 0.18, respectively, after 84 months (women 90.0%, men 91.3%) (P = 0.98, P = 0.08,) respectively. The distribution of the BMD around the stem changed during the first 12 months. The ROIs around the proximal stem (ROI 1 and 7) showed the lowest absolute values at the 12-month follow-up and BMD in ROI 7 decreased most during the further follow-up until 84 months. The cross-sectional study (group B) showed no significant difference in BMD (net avg) values at a median of 156 months follow-up compared to the 12-month values (group A) (women: P = 0.77, men: P = 0.44). Initial BMD, implant diameter, and body mass index did not influence BMD loss (net avg) in this study, whereas age showed a weak correlation with BMD loss. The results show that after the initial remodeling process, no relevant further bone loss (net avg) occurs up to 84 months postsurgery, and values after a median of 156 months are similar. Normative long-term changes in the periprosthetic bone can be demonstrated in defined ROIs after implantation of a tapered corundum-blasted titanium stem with a good clinical result.

Periprosthetic Mineralization Around Cementless Total Hip Endoprosthesis: Longitudinal Study and Cross-Sectional Study on Titanium Threaded Acetabular Cup and Cementless Spotorno Stem with DEXA

In a prospective longitudinal study over 2 years and a separate cross-sectional study more than 5 years after operation, we analyzed periprosthetic bone mineral density (BMD) after cementless total hip arthroplasty (THA) (press-fit cementless Spotorno stem, Mecron threaded acetabular cup) by dual-energy X-ray absorptiometry (DEXA). BMD was analyzed in a longitudinal prospective study (n = 53 patients: 29 women, 24 men) and in a separate cross-sectional study (n = 23 patients: 13 women, 10 men) with good clinical outcome (Merle d’ Aubigne score > 12). Regions of interest were defined according to Gruen (ROI 1–7) and as netto average ROI (NETAVG I) for the periprosthetic femur, and according to De Lee and Charnley (ROI I-III) and as NETAVG II for the periprosthetic acetabulum. BMD during follow-up was compared with immediate postoperative values of the affected limb. Mean precision error (CV%) was 2.6 ± 0.5% for ROI 1–7 and 1.3 ± 0.9% for ROI I–III. BMD significantly decreased in the periprosthetic femur and acetabulum during the first 3 months after operation. At the femur, BMD (NETAVG I) for women and men, respectively, was 92.4% and 87.5% at 6 months, then 89.4% and 96.2% at 2 years. ROIs around the proximal stem showed the lowest absolute values and decreased most during follow-up (to 79.9% ROI 1 and 68.2% ROI 7, respectively). Mineralization around the cup (NETAVG II), respectively, amounted to 81.1%, 82.6% at 6 months, then 80.1% and 93.8% at 2 years. The medially placed ROI II demineralized most (respectively, 72.1% and 76.7%). More than 5 years after THA, BMD in the femur showed little change, but decreased significantly to 76.4% and 79.1%, respectively, around the cup (NETAVG II). DEXA is a useful method for analyzing changes of mineralization around cup and stem of cementless THA. The results reflect the different stress on the periprosthetic bone after implantation of THA in defined ROIs, supporting earlier reported good clinical results of the Spotorno stem and increased loosening rate of threaded acetabular cups after 5 years.

Adenovirus-Mediated Gene Transfer of Growth and Differentiation Factor-5 into Tenocytes and the Healing Rat Achilles Tendon

Growth and differentiation factor-5 (GDF-5) is known to induce tendon tissue and stimulate tendon healing. The hypothesis was that adenoviral GDF-5 transfer leads to transitory transgene expression and improves Achilles tendon healing. In vitro experiments were first performed with rat tenocytes. Transgene expression was evaluated by RT-PCR, Western blotting and GDF-5-ELISA. In vivo virus dosage and transgene expression were examined by a marker gene transfer (LacZ and luciferase). In the main experiment in 131 rats, adenovirus particles (3× 1010) were injected into transected Achilles tendons. The time course of GDF-5 mRNA expression was assessed by real-time RT-PCR. Histology and biomechanical testing were used to evaluate tendon healing and tensile strength. In vitro GDF-5 was secreted with a maximum after 2 weeks (330 ng GDF-5/106 cells per 24 hr). In vivo GDF-5 transgene expression showed a maximum at 4 weeks. At 8 weeks, GDF-5 specimens were thicker (p < 0.05) with a trend to higher strength (p = 0,064). Histology showed greater cartilage formation in type II collagen stains than in controls. Injection of adenovirus particles successfully can deliver the GDF-5 gene in healing tendons and leads to thicker tendon regenerates after 8 weeks. This technique might become a new approach for nonsurgical treatment of tendon injuries.

Osteoporosis in patients with paralysis after spinal cord injury

Abstract In a cross-sectional study, 46 male patients with paralysis after spinal cord injury (average age 32 years; injuries sustained from 1 to 26 years ago; 33 Frankel A, 13 Frankel B, C, D) were examined clinically and by dual-energy X-ray absorptiometry (DEXA). Their bone mineral density (BMD) values were compared with age-related controls and correlated to clinical parameters. BMD was reduced in the proximal femur (p < 0.05) and the distal forearm (p < 0.05), but not in the lumbar spine. Demineralisation was influenced in the proximal femur (Z-score –2.95) by immobilisation after surgical treatment. Patients suffering from complete lesions had significantly lower BMD in the lumbar spine (–1.47) compared with patients with incomplete lesions (+0.02). BMD was not significantly influenced by the level of the lesion and the ambulatory status. Long-term monitoring showed significant demineralisation in the proximal femur (r = –0.36) and the distal forearm (r = –0.4), but not in the lumbar spine (r = –0.21). By correlating BMD with clinical parameters, it can be deduced that, firstly, immobilisation after surgical treatment should be reduced to a minimum; secondly, that every effort must be expended to prevent turning an incomplete into a complete lesion; and finally, that rehabilitation treatment should be lifelong.

MIDDLE-TERM RESULTS OF THREADED ACETABULAR CUPS: HIGH FAILURE RATES FIVE YEARS AFTER SURGERY

We report our results using three different threaded acetabular components (Mecring A, Mecring B and Weill) in 715 hips with a follow-up of between one and ten years (median: 99.1, 56.5, 38.3 months, respectively). All cups were implanted with one type of cementless stem. The clinical results were good or acceptable in about 70% of the hips, but signs of loosening with radiolucency and/or migration were found in 10.1%. Radiological evidence of loosening did not correlate significantly with the clinical outcome. Pain was not a reliable indicator of loosening and its absence sometimes allowed severe osteolysis to develop. Twenty-five hips were revised (3.5%) for aseptic loosening of the acetabular component. Kaplan-Meier estimates of the cumulative rate of failure showed a rapid increase five years after the initial operation, but no significant correlation with gender, age or weight. The high rate of failure indicates that further use of these acetabular components cannot be recommended. Annual radiographs are required to assess osteolysis even if the patients are free from pain.

Relationship between calcifying tendinitis and subacromial impingement: A prospective radiography and magnetic resonance imaging study

In a prospective study radiographs and magnetic resonance images of 75 patients with calcifying tendinitis of the rotator cuff were analyzed. The aim was to evaluate any relation between calcifying tendinitis and subacromial impingement. A total of 83% of the calcifications were located in the supraspinatus or the adjoining part of the subscapularis tendon. On T1-weighted images they could be demonstrated with high accuracy as areas of decreased signal intensity. A magnetic resonance imaging categorization of the calcium deposits was carried out by means of a differentiation of form, outline, and density. A partial rotator cuff tear was found in one shoulder; in 11% variable aspects of degenerative alteration of the affected tendon were seen. By analysis of the radiographic outlet view 16% of the cases had a type III acromion. In conclusion, little correlation exists between calcifying tendinitis and additional findings associated with subacromial impingement.

Influence of extracorporeal irradiation on the reintegration of autologous grafts of bone and joint

We studied the effects of irradiation on the reintegration of autologous osteoarticular grafts over a period of 24 weeks in a canine model. In 16 foxhounds the medial femoral condyle was resected, irradiated and immediately replanted. In the control group resection and replantation were performed without irradiation. Reintegration was assessed by macroscopic analysis, histology, radiography and gait analysis. Reintegration was equal at 12 weeks, but significantly inferior in the irradiated group after 24 weeks with delayed bone remodelling. The articular cartilage showed modest degeneration. Conventional radiography and histology showed corresponding changes. Limb function was adequate but the gait was inferior in the treated group.

Operative Therapie — 1. Strahl

Der Hallux rigidus ist eine zunehmende Einsteifung im Groszehengrundgelenk, beginnend mit der schmerzhaften Einschrankung der Dorsalextension. In die Entscheidung, welche Operation gewahlt wird, sollte immer die Beurteilung des Rontgenbildes mit eingebunden werden. Hier hat sich die Einteilung von Hattrop u. Johnson (1988) in 3 Gruppen bewahrt:

Hallux rigidus – Resektionsarthroplastiken

Die Resektionsinterpositionsarthroplastik bei Hallux rigidus nach Keller-Brandes galt in fruheren Jahren in vielen Kliniken als Standardverfahren zur Behandlung des Hallux valgus (Keller 1912; Brandes 1929). Die aktuelle Differenzierung der Therapieschemata nach Patientenalter, Arthrosegrad und klinischem Befund sowie der Anspruch des Patienten hat zwischenzeitlich nahezu zu einer Verdrangung der Methode durch Arthrodese, Endoprothese oder gelenkerhaltende Verfahren gefuhrt. Es besteht weitgehend Ubereinstimmung, die Anwendung der Resektionsinterpositionsarthroplastik auf altere Patienten mit geringerem funktionellem Anspruch zu beschranken (Wulker 2002) bzw. auf Patienten, die nicht uber langere Zeit entlasten konnen.