PURPOSE: There are two problems using structural allografts in revision total hip surgery. The long-term stability of bulk allografts and the intraoperative primary stability of the graft and implant limit the success of this revision philosophy. The purpose of this study was to analyse the reasons of early loosening of cementless cups after reconstruction with bulk allografts. METHOD: In a retrospective study 78 revisions were analysed radiologically. The preoperative stage of bone destruction, the size of allografts, the implant-allograft coverage, and the position of implants were analysed in X-ray series. RESULT: There were 12 (15.3%) cases with aseptic and 5 (6%) cases with septic cup loosening, after revision surgery, with an average follow-up of 37 (25-84) months. All of these failures were registered in the first 12 months postoperatively. Large bone defects and an implant-allograft coverage of more than 50% are significant (p < 0.001) risk factors of early aseptic loosening. CONCLUSIONS: It is important to give careful attentions to primary stability, especially in revision total hip arthroplasty using structural allografts and cementless cups. For primary stability as well as secondary stability a stable fixation with as large as possible areas of contact between implant and living bone is necessary. The limit of the method (allograft and cementless cup) is to be seen in stage 2B according Paprosky (1990). In larger defects alternative reconstruction methods have to be used.

Acetabulum↗

PubMedDate not supplied

[ROBODOC--a path into the future of hip endoprosthetics or an investment error?].

GOAL: The Orthopaedic Department of Martin-Luther-University has been using computer-guided, robot-assisted surgery in cementless total hip arthroplasty since June 1997. The goal of the present paper is to critically evaluate the advantages and disadvantages of the ROBODOC system when using two different femoral components and the employment of the system in orthopaedics in general. METHOD: Between June 1997 and August 1999 87 procedures have been performed using the ROBODOC system. 48 ABG stems and 39 OSTEOLOC stems manufactured by HOWMEDICA were used. The results are based on a prospective study. RESULTS: The main advantage of the system is the excellent three-dimensional preoperative planning and the precise execution of the preoperative plan during surgery. Problematic situations of the proximal femur can be evaluated and the optimal position of the femoral component can be guaranteed. Investigations on cadaver femurs showed significant differences in the bone-implant contact. The first results let us expect some advantage in congenital and acquired femoral deformities. CONCLUSION: The ROBODOC system has to be critically considered as an alternative to hand implantation. In our opinion, it should be used only under certain circumstances considering the current technical progress. Only in these cases the potential of the system can be used beneficially.

Arthroplasty, Replacement, Hip↗

PubMedDate not supplied

[Early results of a prospective study in patients with computer-assisted femur shaft preparation in total hip endoprosthesis implantation (Robodoc system)--indications, outcome, complications].

AIM: Indications, results, advantages and disadvantages of the computer-guided femoral preparation in total hip arthroplasty (Robodoc) in our patients are recorded and represented. METHOD: 41 patients who underwent a computer-guided femoral preparation in total hip arthroplasty (Robodoc) were examined after 1 year on average in a prospective study. The evaluation was made using the Harris Hip Score. The advantages and disadvantages of the Robodoc-assisted surgery are described. RESULTS: More than 80% of the patients had a good or very good result (> 80 points of Harris Hip Score) 3 month after surgery; after 6 months in 20 of 21 patients a score of more than 85 pts. was calculated. The following complications were noticed: thrombotic embolism (2) with one lethal embolism included, fracture of the greater trochanter using the straight stem (3), aseptic drainage due to hematoma (2). 12 patients noticed a postoperative pain at the distal marking pin location (condylus femoris medialis) for an average of 3 months. CONCLUSION: Generally, Robodoc-assisted surgery may be performed in all uncemented total hip arthroplasties. The individual indication should be checked because of the increased effort of surgery, the advantages and disadvantages, and the non-proven better long-term results in comparison to the regular technique. It seems that the Robodoc system provides advantages in post-traumatic arthritis and deformities of the proximal femur (varus and valgus neck) on account of the computer-aided preoperative planning and correct operative realization.

Adult↗

PubMedDate not supplied

[DNA flow cytometry of bone metastases of different primary tumors].

AIM: Some human tumors of different primary localization metastasize preferably into the bone. This concerns especially kidney, breast, prostate and lung cancer. So far, the reason for this specific pattern of metastazing could not sufficiently be clarified. The aim of the study was the search for mutuality in the results of the DNA analysis of bone metastases of different primary tumors and their importance for prognosis and therapy. METHOD: In this study, the DNA content of 40 excised bone metastases of different primary localisation has been determined by flow cytometry. By means of the DNA distribution pattern, the percentage of tumor cells in the particular cell cycle phase as well as the respective ploidy condition have been calculated. RESULTS: Altogether, no preference of DNA diploid or DNA aneuploid stem cell lines could be found. Whether this can be applied for metastases of all primary tumors has not been clarified yet. The fact that, in 11 out of 12 tested cases of the same metastasis, DNA diploid as well as DNA aneuploid areas could be demonstrated, seems to be fundamental. CONCLUSION: There exist a high variability of the extent of dysregulation and the intensity of the growth of bone metastasis. This does not seem to be crucial for the preferable tendency to metastazise into the bone. Due to the often insufficient tumor amount for material extraction from different areas and the large amount of DNA diploid metastases after flow cytometry analysis there should be considered the additional use of pictorial analytical methods for the DNA ploidy and proliferation assessment. A knowledge of the intensity of the course and the degree of dysregulation of tumor cell proliferation of bone metastases is beneficial in order to estimate the prognosis and to design an individual therapy regime.

Adult↗

PubMedDate not supplied

[Advantages of minimal invasive total hip replacement in the early phase of rehabilitation].

UNLABELLED: In arthroplasty the term "minimal invasive" not only refers to the length of the skin incision but more so to its soft tissue and thereby muscle-protecting features. STUDY AIM: The aim of this study is to compare the early postoperative mobilisation and rehabilitation of the different surgical approaches in cementless total hip arthroplasty. METHODS: 27 patients underwent a total hip replacement (Trilogy cup, MAYO stem) via a ventral minimal invasive approach (one incision technique) (MIS group). 23 patients underwent a total hip replacement with the same implant via a anterolateral transgluteal approach (standard group). We evaluated the Harris Hip Score (HHS), the visual analogue scale (VAS) for pain and patient satisfaction preoperatively as well as 3 days, 10 days, 6 weeks and 3 months postoperatively. RESULTS: After 3 and 10 days the MIS group showed better scores for pain, gait and mobilisation as well as for the overall HHS compared to the standard group. These differences could not be shown 6 weeks postoperatively. The MIS group had a significantly higher rate of complications with 22 % transient impairment of the lateral cutaneous nerve. CONCLUSION: The patients of the MIS group showed a better mobilisation and rehabilitation during the early postoperative period. This can be attributed to the lessened intraoperative damage of to soft tissue and especially muscle damage. Due to the increased rate of nerve irritations, we modified our surgical approach. The minimal invasive approach to modern hip joint arthroplasty remains a non-standard technique. Compared to the standard approach it carries additional risks (like nerve damage and malpositioning of the implants and thus should remain in the hands of the experienced orthopaedic surgeon in specialised orthopaedic centres.

Aged↗

PubMedDate not supplied

[Wristing -- a new opportunity in digital migration analysis of uncemented total hip arthroplasty].

AIM: The aim of this study was to evaluate a computer program (Wristing) for digital migration analysis in hip endoprotheses and to assess the most accurate landmarks in hip-alone radiographs. METHOD: Conventional radiographs of 52 patients with a minimum follow-up period of seven years and five consecutive radiographs were digitised and different landmarks were compared. The parameters with the greatest accuracy were analysed to calculate inter- and intra-observer variability in 30 radiographs. Digital and manual measurement techniques were compared with each other. RESULTS: The obtained accuracy (95 % confidence interval) was 1.7 to 2.2 mm and 2.8 degrees to 3.2 degrees for the most accurate landmarks. The intra-observer variability was 0.12-0.3 mm; 0.28 degrees and the inter-observer variability ranged from 0.14 to 0.45 mm and 0.5 degrees to 0.53 degrees . In comparison to the migration measurement with pencil and ruler (precision: 0.24-0.67 mm; 0.57-0.74 degrees ) the new software (precision: 0.12-0.3 mm; 0.28 degrees ) was associated with a superior accuracy (t test: p < 0.001). CONCLUSION: With the program "Wristing" migration in hip-alone radiographs could be recorded with high precision. The integrated sketch, zooming and the current possibility of comparing radiographs and patient data with previous follow-ups and examples leads to a high inter- and intra-observer accuracy and is very useful in day-to-day clinical practice.

Acetabulum↗