Adequate resection of malignant osseous tumors of the pelvis within wide margins is demanding surgery. To avoid disabling hemipelvectomies, during the seventies of the last century internal hemipelvectomy combined with a partial pelvic replacement had become a new surgical and meanwhile standard procedure. To achieve adequate reconstructions of the osseous pelvis custom-made replacements were recommended. In the very early stages of this type of surgical procedure using megapros-theses, individual pelvic models were manufactured but, until recently, little is known about the accuracy of such models. Thus, it was the aim of this retrospective study to evaluate this.

We analysed the charts of 24 patients (25 pelvic models) for whom an individual model of the osseous pelvis had been constructed to manufacture such a tool and to enable the surgeon a better intraoperative orientation. Two patients refused surgery. Thus, in 23 patients surgical resection of parts of the bony pelvis was performed followed by either a partial pelvic replacement (13 x), hip transposition procedure (5 x), ilio-sacral resection (4 x) or revision surgery (exchange of a partial pelvic replacement).

In all patient who received a partial pelvic replacement, the fit of the replacement was optimal, in none of them a major unplanned resection was necessary. The same was observed in patients who received a hip transposition procedure or an ilio-sacral resection.

Oncologically, in most of the patients we achieved wide resection margins (14 x). In only 5 patients the margins were marginal (4x) or intralesionsal (1 x). In two cases the aim was a palliative resection because of a metastatic disease (1x) or benign entity (1 x).

Thus, pelvic models are helpful tools to planning the manufacture of partial pelvic replacements and ensuring optimal osseous resection of the involved bone. Further attempts have to be made to evaluate the aim of navigational techniques regarding improvement of the accuracy of the osseous and the soft tissue resection.

Clear cell sarcoma (CCS) is a rare and highly malignant soft-tissue sarcoma (STS) constituting 1% of all STS. It most often appears in the soft tissue closely assocíated with tendons, aponeuroses or fascial tissue of the distal extremities. It shares features of melanomas, hence is dubbed as a soft-tissue melanoma or clear cell sarcoma of the tendons and aponeuroses (CCSTA). CCS differs from the more common STS by its more aggressive growth and greater propensity to metastasise to lymph nodes, bones and lung. On a molecular basis, CCS is characterised by the chromosomal translocation.

Clinically, the tumor is firm, slowly growing and painless in half of the cases, thus rarely awakening suspicion of a STS. Thus, the diagnosis is difficult. Furthermore, on an MRI the tumor exhibits mostly a homogenous mass with a higher signal intensity as compared to muscle on T1-weighted images and implies a benign tumor.

The most important treatment is a wide resection to ensure local control. Little is known about neo- and/or adjuvant chemotherapy or radiation. Regarding chemotherapy different substances (doxorubicin, ifosfamide, cisplatin, mesna, dacarbazine, cyclophosphamide) have been administered under different conditions (single or combined substances, different doses, neo- or adjuvant). There are also some reports displaying the advantages of caffeine-assisted chemotherapy.

Under similar different circumstances radiation therapy was applied.

Most important prognostic factors are the presence of tumor necroses, size and regional lymph node metastases, local recurrence and distant metastases.

The reported 5-year survival ranges from 48% to 68%, the 10-year survival from 36% to 41%. Summarising all reports there is a need at least for a retrospective study to gather information about more patients.

We reviewed 25 patients in whom a MUTARS megaprosthesis with a conical fluted stem had been implanted. There were three types of stem: a standard stem was used in 17 cases (three in the proximal femur, nine in the distal femur and five proximal tibia), a custom-made proximal femoral stem in four cases and a custom-made distal femoral stem in four cases. The mean age of the patients was 40.1 years (17 to 70) and the mean follow-up was for 2.5 years (0.9 to 7.4).

At follow-up two patients had died from their disease: one was alive with disease and 22 were disease-free. One of 23 prostheses had been removed for infection and another revised to a cemented stem. The mean Musculoskeletal Tumor Society score was 24.9 (12 to 30) and the mean Karnofsky index was 82% (60% to 100%).

There was no radiological evidence of loosening or subsidence. Stem stress shielding was seen in 11 patients and was marked in five of these.

There were five complications, rupture of the extensor mechanism of the knee after extra-articular resection in two patients, deep venous thrombosis in one, septic loosening in one, and dislocation of the hip in one.

The survival rate after seven years was 87% (95% confidence interval (CI) 83 to 91) for the patients and 95% (95% CI 91 to 99) for the megaprosthesis. A longer follow-up is needed to confirm these encouraging results.

One of the most important factors influencing therapeutical decisions in orthopaedic surgery are long-term results. Although, osteochondritis dissecans (o.c.d.) of the femoral condyles is the most often occurring location little is known about long-term results. Furthermore, it is of interest to see the time course of such patients regarding the development of secondary osteoarthritis. Thus, it was the aim of our study to re-analyse patients suffering from o.c.d. of the femoral condyle which had been operated have been followed up after a medium time-intervall.

Material & methods: 97 of 147 with o.c.d. of the femoral condyles which were operated using different surgical techniques depending on the stage were followed-up clinically (Lysholm-Score) & radiologically (Arcq- classification/Tapper- & Hoover-score for OA). Results were analysed depending on the age, stage and surgical technique. In 2nd follow-up ten years after the first follow-up patients were reexamined with the same clinical and radiological scores.

Results: At 1st follow-up we found a median Lysholm-Score of 83.7 (21–100, SD 19.6) pts.. Regarding the OA-changes in 56.3% no changes, in 21.9 % 1°-changes, in 3.1% 3°-changes, in 6.3 % 3°-changes & in 12.5 % 4° changes. The mean stage postop. was 0.97 SD 1.4. Ten years later similar results were found: in 56.3% no osteoarthritic changes were seen. 1°-changes were found in 21.9%, 2°-changes in 3.1% and 3°-changes in 6.3% and severe OA 4°-changes were found in 12.5%. In comparison to the 1st follow-up at the 2nd follow-up no individual changes could be detected in 73 %, a slight impairment in 11.5 % & a slight improvement in 15.4%. In most of the patients osteoarthritic changes were slight & did not show a severe impairment after a mean of 20.3 years.

Depending on the age (the stage of the growth plate open vs. closed) adolescents exhibited no or slight oa-changes in 83.3% & moderate changes in 16.7%. Severe oa-changes were not detectable. Adults exhibited a distinct higher incidence of oa (no o.-a.: 37.5%/1°: 25%/2°: 12.5% 3°:/12.5%/4°:12.5%). Regarding the surgical technique retrograde technique leaving the cartilage layer intact resulted in distinct better results than those perforating the cartilage layer.

Conclusion: Best long-term results with a low incidence of OA are to obtain in cases with o.c.d. with intact cartilage layer not necessitating cartilage damage. Worst results are seen in adult patients with 4°-lesions.

Our aim was to examine the potential of autologous perichondral tissue to form a meniscal replacement. In 18 mature sheep we performed a complete medial meniscectomy. The animals were then divided into two groups: 12 had a meniscal replacement using strips of autologous perichondral tissue explanted from the lower rib (group G) and six (group C) served as a control group without a meniscal replacement. In all animals restriction from weight-bearing was achieved by means of transection and partial resection of tendo Achillis. Six animals (four from group G and two from group C) were each killed at 3, 6 and 12 months. The grafts and the underlying articular cartilage were removed and studied by gross macroscopic examination, light microscopy, SEM, polarised light examination, and by biomechanical tests.

In all the transplanted animals a new perichondral meniscus developed. After three months the transplants resembled normal menisci in size and thickness, while in the control animals only small rims of spontaneously grown tissue were seen. Microscopically, the perichondral menisci showed a normal orientation of collagen fibres and normal cellular characteristics, but in the central region, areas of calcification disturbed the regular tissue differentiation. Healing tissue in control animals lacked the normal fibre orientation and cellularity. SEM of perichondral menisci showed surface characteristics similar to those of normal sheep menisci without fissures and lacerations; the control specimens had these defects. The femoral and tibial cartilage in contact with the new menisci had normal surface characteristics apart from one animal with slight surface irregularities. Control animals showed superficial lesions after three months which increased at six to 12 months postoperatively. Microangiography of the newly grown tissue demonstrated a less intense vascularisation after three months when compared with normal menisci.

The failure stress and tensile modulus of perichondral menisci were significantly lower than those of normal contralateral menisci, and spontaneously regenerated tissue in meniscectomised animals had even lower values. There were no significant differences in values between newly grown perichondral menisci and spontaneously grown tissue.