[Long-term results of thrust plate prostheses: comparison of patients younger than and older than 50 years]. / Langfristige Analyse der Druckscheibenendoprothese: Vergleich von Patienten unter und über 50 Jahren.

BACKGROUND: Hip replacement in patients younger than 50 years old is no longer an exception in view of the increasing necessity for care. The aim of the present study was to analyze whether the results after implantation of thrust plate prosthesis (TPP) with metaphyseal anchorage are equal for patients below 50 years compared to older patients. PATIENTS AND METHODS: The investigation comprised 465 TPP implantations. In 149 TPP the patient age was below 50 years (group A) und in 316 TPP cases above 50 years (group B). Clinical and radiological evaluation of the results for both groups was carried out as well as a differentiated survival analysis with defined endpoints. RESULTS: Survival analysis of group A (96%/13.2 years) showed a significantly improved survival rate compared to group B (86%/12.5 years). Additionally, the risk of prosthesis and/or radiological signs loosening of was significantly lower in group A than in group B (p <0.05). CONCLUSION: Comparison of long-term results of prostheses with intramedullary fixation shows that the anchorage principle of TPP with bone-saving implantation to the proximal femur is justified especially for patients below 50 years of age.

Clinical evaluation of a novel press-fit acetabular cup using "Ein-Bild-Roentgen-Analysis" (EBRA): A positive short-term prognosis.

INTRODUCTION: Demographic change and demand for high quality of life lead to increasing implantation numbers. Aim of this study was to compare the Plasmafit® cup to Allofit® and Plasmacup®. METHODS: The study included 174 patients who had received 33 Plasmacup®, 68 Allofit® and 73 Plasmafit® cup implants. These were reviewed postoperatively, after 6 months control and after 12 months. RESULTS: No significant progressive migration could be discovered in any of the cup systems. At each follow-up the cups showed nearly constant values. CONCLUSIONS: All examined acetabular cups showed excellent migration behavior within the first 12 postoperative months.

[Comparative study after hamstring ACL plasty with RigidFix (pin fixation) and EndoButton (anchor fixation)]. / Vergleichende Studie nach vorderer Hamstring-Kreuzbandplastik mit RigidFix (Pinfixation) und EndoButton (Ankerfixation).

AIM: Within a prospective case group study, two hamstring fixation techniques, a pin fixation with RigidFix (RF) and an anchor fixation with EndoButton (EB), were compared. METHOD: 67 patients were followed clinically and by MRI preoperatively (t0), at six months (t6) and at twelve months (t12). In one group (N = 21), EB was used for representing a juxta-articular graft fixation. The second group (N = 46) with RF was used to represent the ab-articular fixation. KT-1000 stability measurement, IKDC, Lysholm and Tegner scores were used to determine the clinical outcomes. Reflux and tunnel widening (TW) were investigated by MRI. RESULTS: The KT-1000 values were slightly more stable at t6 (EB: 2.1 +/- 4.1 mm, RF: 1.0 +/- 2.5 mm) in the RF group (p = 0.044) but equalised later at t12 (EB: 0.5 +/- 3.1 mm, RF 1.0 +/- 2.4 mm). The median Tegner score at t6 (EB: 4.3 +/- 1.2, RF 4.1 +/- 1.7) and t12 (EB: 5.9 +/- 1.8, RF 5.4 +/- 2.0) were comparable (p = 0.692). The mean Lysholm score at t6 (EB: 90 +/- 11, RF: 91 +/- 8.9) and t12 (EB: 95 +/- 7.5, RF: 95 +/- 7.4) was comparable in each group (p = 0.589). The same was valid in the median of the IKDC score at t6 (EB: II, RF III) and t12 (EB: II, RF III). The category "femoral reflux" showed slight minimal fringe in the EB group at t6 but aligned to "no reflux" together with the RF group at t12 (NS, p = 0.550). A tunnel widening was not detectable in either of the groups.

[Long-term results of the cementless conical balgrist expansion cup--comparison analysis to the Zweymüller-Alloclassic screw cup]. / Langzeitergebnisse der zementfreien konischen Balgrist-Spreizpfanne--Vergleichsanalyse zur Alloclassic-Schraubpfanne.

AIM: The press-fit fixation of the conical Balgrist expansion cup (Allo Pro, Baar, Schweiz) is realised by the help of a (titanium alloy) split ring and a metal-backed inlay. The results and fixation principles of the cement-free Balgrist hip socket are analysed within a clinical and radiological long-time study and compared with those of the conical Zweymüller-Alloclassic CFS (Zimmer-GmbH, Winterthur, Schweiz) screw cup for a concluding evaluation. METHOD: Between 1993 and 2003, 277 Balgrist hip sockets and between 1994 and 2000 130 Alloclassic-Zweymüller screw cups were performed consecutively in 364 patients considering similar indications with an average age of 54.6 years and 51.9 years, respectively. The clinical investigation was carried out with the Harris hip score (HHS). Radiological evaluation included a manual migration analysis according to Sutherland et al., Nunn et al. and Effenberger et al.; radiolucent lines were registered according to the zones of DeLee and Charnley. The survival rate of both cups was calculated on the basis of the Kaplan-Meier and the life-table analyses. RESULTS: Besides 4 (1.4%) aseptic loosenings, 5 Balgrist cups (1.8%) had to be replaced because of infection and another 1 (0.8%) because of persisting pain. Three Balgrist sockets (1.1%) showed a migration > 2 mm. In the Alloclassic group 1 cup (0.8%) was considered as being migrated, another cup (0.8%) had to be replaced due to infection. Considering aseptic loosening and radiological migration as an end point, the cumulative survival of the Balgrist cup at 13 years was 97.3%, that of the Zweymüller-Alloclassic cup at 10 years was 99.2%. In comparison with the Alloclassic group, the Balgrist hip sockets showed increased radiolucent lines of zone 1 (p < 0.001), without any effects on the survival time or the clinical result however. Both cups resulted in good to excellent clinical results in the HHS (91 points). CONCLUSION: The long-term analysis of the Balgrist hip socket proved that the concept of the retightening conical expansion cup leads to good clinical results and fulfils the minimum survival rate of 95% at 10 years as demanded by Delaunay and Kapandji. The good results obtained with the aid of this concept are comparable to those of the Alloclassic screwing cup.

[Eight-year results of the femoral neck prosthesis ESKA-CUT]. / 8-Jahres-Resultate der Schenkelhalsprothese ESKA-CUT.

AIM: With the help of a clinical and radiological follow-up evaluation 8 years after implantation of the femoral neck prosthesis CUT (ESKA Implants, Lübeck Germany), the question of whether this metaphyseal anchoring implant is recommendable in young patients will be answered. METHOD: Between 2000 and 2001 82 CUT-prosthesis procedures were performed in 79 patients (38 female, 41 male patients; average age 51.3 years) and evaluated prospectively. The clinical investigation was carried out according to the criteria of the Harris Hip and Merle d'Aubigné scores. Radiological periprosthetic bone changes were registered and a measurement of the CCD angle and femoral offset was performed. The survival rate was calculated according to both the Kaplan-Meier and the life-table analyses. RESULTS: During the 12-month follow-up examination the HHS (48.4 preop.) as well as the Merle d'Aubigné score (10 preop.) increased significantly to an average value of 85.1 and 15.8, respectively (p < 0.000). Cumulative survival with replacement of the prosthesis as an end point at 8 years was 49.6 %. Due to 25 aseptic loosenings, three periprosthetic infections and three cases of persisting thigh pains, 31 replacements of the femoral neck prosthesis became necessary up to June 2008. The implantation of the CUT prosthesis led to a significant valgisation (p < 0.001) of 17.4 degrees degrees with a consecutive reduction of the femoral offset of 5 mm. Radiologically periprosthetic progressive radiolucencies, hypertrophic cortical bone changes as well as atrophy of the calcar femoris were often evaluated and interpretated as a sign of a stress shielding and migration process. CONCLUSION: The analysis of the eight-year follow-up of 82 CUT prostheses shows that the implant does not fulfil our expectations of a femoral neck prosthesis, in spite of the possibility of a less invasive and bone-saving implantation technique. In view of unacceptable survival rates, valgisation changes of the joint geometry and critical changing procedures, from our point of view the femoral neck prosthesis CUT does not represent a recommendable alternative implant in young, active patients.

[Results after replacement of femoral neck prostheses - thrust plate prosthesis (TPP) versus ESKA cut prosthesis]. / Ergebnisse nach Wechsel von Schenkelhalsprothesen - Druckscheibenprothese versus ESKA-Cut-Prothese.

AIM: The aim of this study was to analyse and evaluate comparatively loosening mechanisms, failure frequency, surgical changing strategies and results after replacement of thrust plate prostheses (TPP) and ESKA Cut prostheses. METHOD: Between 1993 und 2007, 465 TPP and in the years 2000 and 2001 82 ESKA Cut prostheses were performed and evaluated prospectively. Until 2007 46 change interventions of the TPP and 35 of the CUT prosthesis became necessary. All patients who received a stem revision procedure in our hospital were included within this study. Besides the evaluation of clinical results according to the criteria of the Harris Hip Score on the average at 15.6 months (+/- 14.4) postoperatively, radiological loosening processes and surgical difficulties were registered. Furthermore, an analysis of perioperative data was performed according to some criteria of the German Federal Office of Quality Assurance (BQS), such as duration of the surgery, intraoperative blood loss and complications. Statistical investigations for comparative analysis as well as survival analysis of both groups were calculated using SPSS for Windows 13.0. RESULTS: The mean age of the 46 patients who had to undergo revision surgery after TPP was 60.1 years, that of 35 patients in whom revision surgery was necessary after receiving an ESKA Cut femoral neck stem was 56.6 years. The survival rate analysis according to Kaplan-Meier at 13 years was 89.4 % (TPP) and 53.6 % at 66 months (ESKA Cut). In all cases the partial osteointegration of the tripod surface of the loosened Cut prosthesis complicated the explantation. It led on the one hand to a significant difference of the surgery duration and on the other hand to an increased frequency of fractures of the trochanteric region. The conversion of the TPP on standard type stems was usually free of problems. The HHS increased significantly to the averages of 86.6 (TPP) or, respectively, 91.69 (ESKA Cut) after revision. CONCLUSION: In comparison with the usually problem-free changing procedure of the TPP to a standard type stem, the revision surgery of the Cut prosthesis becomes substantially more complex and leads frequently to complications. In view of unacceptable survival rates, the Cut prosthesis does not represent an alternative implant in young patients. Except for the implantation technique, which does not allow a less invasive surgical procedure, the TPP fulfils the requirements of femoral neck prosthesis due to acceptable survival rates and good convertibility.

[Clinical and radiological results of the thrust plate prosthesis in patients with aseptic necrosis of the femoral head]. / Klinische und Radiologische Ergebnisse nach Implantation der Druckscheibenendoprothese (DSP) bei Patienten mit Femurkopfnekrose.

AIM: In this study, we investigated the results after implantation of the thrust plate prosthesis (TPP) in patients with femoral head necrosis. We intended to answer the question if the femoral neck prosthesis, inaugurated by Huggler and Jacob in Switzerland, which needs a good bone stock for a successful implantation, is a recommendable alternative to other cementless intramedullary fixed prostheses. METHOD: In a prospective study, 62 patients who had received 70 TPP because of femoral head necrosis as a result of various aetiologies between 1993 and 2004 were examined clinically and radiologically. The follow-up examinations were carried out 3 and 6 months postoperatively and subsequently once a year. The mean follow-up interval was 6.0 +/- 1.9 years (1.0-10.2 years). Clinical examination was carried out using the Harris hip score; the radiological examination was performed according to predefined criteria in an exact a.-p.-view. Four sectors can be distinguished: A corresponds to the femoral neck stump, B to the bony stock cranial (= 1) and caudal (= 2) to the mandrel of the prosthesis, C is the region above and under the bolt and D is the cortical area around the lateral plate. Furthermore, we performed a Kaplan-Meier survival rate analysis. RESULTS: We found excellent clinical results. The preoperative Harris score increased from 48.3 to 91.6 +/- 6.6 at 24 months after the operation. Radiolucencies of various relevancies were detected depending on the localisation. We often saw bony atrophy under the thrust plate (sector A: A 1 21.4%, A 2 9.9%) and small radiolucencies along the bolt (sector C 30 % in general). As a pathological finding we interpreted progressive radiolucencies of sector B, which was considered to be a sign of loosening, when they showed a thickness of > or = 2 mm. Therefore, we had to change one TPP. In two additional cases we saw an extended atrophy under the lateral plate, which was also interpreted to be a sign of loosening. The Kaplan-Meier survivorship analysis for 5 and 10 years was 95.1% (95% - 0.95 +/- 0.05). Our study suggests that, in spite of a slightly higher aseptic loosening rate in comparison with cementless stem prosthesis, the thrust plate prosthesis proved worthwhile. On account of our previous experience we consider the TPP to be a good alternative implant, especially for young patients. CONCLUSION: Due to excellent clinical results and nearly identical findings in the survivorship analysis in comparison to cementless stem prostheses, the TPP is also a good alternative implant for total hip arthroplasty in patients with femoral head necrosis. For a successful implantation of the TPP a good bone quality of the proximal femur is necessary. Therefore we cannot recommend the use of a thrust plate prosthesis in patients with femoral head necrosis and simultaneous osteopeny.

[Midterm results after treatment of injuries of the distal extensor mechanism with the MPT-fixateur. A critical analysis]. / Mittelfristige Resultate nach Anwendung des MPT-Fixateurs bei Verletzungen des distalen Kniestreckapparates. Eine kritische Analyse.

Between 1994 and 2000 at our institution 37 patients (8 women, 29 men) with fractures of the lower patellar pole and a proximal avulsion fracture of the patellar ligament underwent a primary surgical repair and patello-tibial fixateur for external protection. All patients underwent immediately after the reconstruction a functional rehabilitation program without any movement limitation and under early full weight bearing. Postoperative follow-up after an average of 58.5 months (range 14 to 102 months) was possible in 26 patients. Physical examination, roentgenographic evaluation and isokinetic testing were performed. The clinical evaluation was carried out according to the strict criteria of the IKDC-score. The radiological measurement of the patella height was carried out using the index of Blackburne & Peel; the femoropatellar changings were registered according to the score of Sperner. The clinical evaluation showed in 8 patients a normal, in 10 patients a nearly normal, in 7 patients an abnormal and only in 1 patient a severe abnormal result. The average muscle strength deficit in comparison to the contralateral knee joint was between 10 % and 20 %. All patients showed clinically and radiologically a sufficient distal knee extensor mechanism. The patella height ratio was in the average 0.82 on the injured and 0.79 on the non-injured side. In 17 cases we didn't saw any femoropatellar arthrosis. Eight patients showed a moderate femoropatellar arthrosis. There was no case with severe femoropatellar arthrosis. By good follow-up results in general we could demonstrate the value of the MPT-fixateur as a dynamic protection method after reconstructive operations of the distal knee extensor mechanism.

[Radiological analysis of the thrust plate prosthesis (TPP)]. / Radiologische Verlaufsanalyse der Druckscheibenendoprothese (DSP).

AIM: The various radiological changes after implantation of the thrust plate prosthesis (TPP) are demonstrated and, with the help of a standardized radiological classification, divided in pathological and non-pathological findings. METHOD: The radiological follow-ups of 167 TPP implanted between 1993 and 1998 was analyzed in this study. The follow-up examination was carried out postoperatively, after 6 months and subsequently every year. The radiological assessment was carried out in an exact a.p. view. We subdivided the images into four sectors: A corresponds to the femoral neck stump, B to the bony stock cranial (=1) and caudal (=2) to the mandrel of the prosthesis, C is the region above and under the bolt and D the cortical area around the lateral plate. RESULTS: Radiolucencies were especially seen in sector A (A 1 = 34.7 %; A 2 = 18%) and sector C (44 %). As a pathological finding, we saw progressive radiolucencies of sector B (6 %), which were interpreted to be a sign of loosening, when they showed a thickness of = 2 mm. Furthermore, in some cases we observed extended atrophy under the lateral plate, which was also judged to be a sign of loosening. CONCLUSION: The radiological changes of the bony stock of the TPP can be divided into physiological adaptation processes because of changed biomechanics and signs of loosening. As a stress-shielding phenomenon we see a progressive atrophy under the thrust plate and simultaneously a sclerosis of the spongious bone above the calcar femoris. An indication for a loosening of the prosthesis is a progressive radiolucency of sector B.

[Midterm results and revisions of the thrust plate prosthesis (TPP)]. / Mittelfristige Ergebnisse und Wechseloperationen nach Druckscheibenendoprothesen (DSP).

AIM: Although already in use for 20 years, the concept of the metaphyseal anchored thrust plate prosthesis has not yet gained general acceptance. Clinical and radiological follow-up examinations were carried out 5 to 8 years after implantation of a TPP. We tried to answer the question if the metaphyseal anchorage of the cement-less TPP is equal to a diaphyseal anchorage of a cement-less stem prosthesis and to define the advantages of the TPP. METHODS: We included 170 of the patients from our clinic with an implanted TPP in this study. Furthermore we reviewed the results of 30 revision hip arthroplasties of the TPP. The clinical examination were carried out using the Harris hip score while the radiological examinations were performed on the basis of predefined criteria. RESULTS: We found good clinical results. The preoperative Harris score of 48.7 increased to 93.7 at 24 months postoperatively. Radiolucencies were detected and were of varying relevance in dependence on their localization. The Kaplan-Meier survival analysis at 8 years was 90.5 %. The clinical results after changing the TPP were also good to excellent. The mean Harris hip score was 87.3. CONCLUSION: Our study suggests that in spite of a slightly higher aseptic loosening rate in comparison to the cement-less stem prosthesis, the thrust plate prosthesis proved to be worthwhile. On the basis of previous experience we assume that the TPP is a good alternative implant especially for young patients.