Aim: During periods of rapid growth hip diseases can deteriorate unexpectedly. This retrospective evaluation should determine standard values that might allow earlier determination of such growth disturbances and a better classification of almost normal findings.

Methods: 520 standardized made and normal pelvis x-rays of children aged 4–16 years were examined under respect to the development of the hip and pelvis itself (20 x-ray pictures per age-group and gender). Among others these parameters were assessed: acetabular index (AC) and ACM-angle, acetabular width, depth and length, width and altitude of the epiphysis, transverse pelvic diameter and pelvic altitude.

Results: At the age 6–14 years boys have a higher ace-tabular index and ACM-angle than girls. The acetabular index decreases up to the age of 15 to 10 in average, the ACM-angle up to the age of 9 years to 47 in boys and 45 in girls to be subsequently constant. The bony acetabulum grows concentrically and spherically in form and slower than the femoral head. The acetabulum of girls is deeper, smaller and stops growing at the age of 14. The pelvic growth proceeds with the exception of iliac width in girls up to the age of 16.

Conclusion: Due to an age depending mechanical load of the femoral head on the acetabulum a mild DDH can develop to severe pathology in times of rapid growth. With the found normal values and its variations it is easier to assess the development of hip joints especially in such cases.

Purpose: To evaluate the vascularisation of the femoral head in children with slipped capital femoral epiphysis (SCFE) before and after surgery with use of contrast-enhanced MRI

Methods and Materials: 20 consecutive children, 13 boys and 7 girls, aged 9–15 years, with slipped capital femoral epiphysis, were included into the study. The classification of SCFE was performed traditionally due to the patient’s history, physical examination and findings of the radiographs. There were no pre-slips, 9 children had acute, 5 children had acute-on-chronic and 6 children had chronic SCFE. The MRI-examinations were performed in a 1.5 Tesla MR-scanner with use of the body coil and all postoperative MR-examinations were carried out within 4 weeks after surgery. The examination protocol included a coronal fat-suppressed STIR-sequence, a coronal contrast-enhanced T1-weighted spin-echo sequence and a sagittal 3D-gradient-echo (FFE) sequence. Morphology, signal intensities and contrast-enhancement of the femoral head were assessed retrospectively by two experienced radiologists in consensus.

Results: Morphologic distortion of the physis, bone marrow edema in the metaphysis and epiphysis and joint effusion were the preoperative MRI-findings of slipped capital femoral epiphysis in each child. In 17 children, who underwent in situ-fixation with a single screw, and in one child, who underwent open reduction of the epiphysis, the vascularisation of the femoral head before and after surgery was normal. An avascular zone in the posterior-lateral aspect of the epiphysis was visible preoperatively in one child, which completely revascularized after open reduction and internal fixation of the epiphysis with two screws. One child with severe SCFE developed avascular necrosis of the femoral head after open reduction and corrective osteotomy through the physis.

Conclusion: MRI allows for accurate evaluation of the femoral head vascularisation before and after surgery in children with slipped capital femoral epiphysis.

Although osteochondral grafting techniques have nearly been perfected, donor site morbidity still causes concern. A synthetic β-tricalcium phospate cement was used in the attempt to obtain a primary closure of such osteochondral defects, while supplying a scaffold for tissue ingrowth.

Twenty merino sheep underwent an osteochondral grafting procedure. The paste-like β-TCP cement was used to fill the ensuing cylindrical, full-thickness defect. Animals were sacrificed after 3 or 6 months.

The macroscopic observations revealed neither osteophytes nor synovial proliferation, while demonstrating coverage of the defect with cartilage-like tissue. After 6 months, all defects were covered with a ”neo-cartilage” and the congruity of the joint surface was restored in 6 of 10 animals. A surface depression was found in the remaining cases. A demarkation of the defect border at the interface with the original cartilage could only be seen in 2 instances. The x-rays of the retrieved distal femurs revealed only traces of the dense β-TCP particles. Microradiographs demonstrated the incorporation of the implant. Fluorescent staining showed continuous bone ingrowth. Histologically, masses of unabsorbed TCP were irregularly distributed through-out the defect. Newly formed bone had filled much of the defect. The histological evaluation confirmed that the surface of the cement was covered with a cartilage-like tissue.

This study showed, that the newly developed in-situ self-hardening resorbable β-tricalcium phosphate cement is easy to handle, hardens in a clinical-type setting, is bioactive and resorbable. Its osteoconductive effect lead to a restoration of biomechanically stable bone and allows for a normal remodeling process. Biomaterials made of β-TCP promise to play a role as a biodegradable scaffold, allowing osteo-blast ingrowth and cartilagenous resurfacing, while being fully resorbed during the process. The cement may also be used to deliver bioactive agents and cells for defect repair in the near future.

Among the wide variety of bone substitutes presently available, pure β-tricalcium phosphate ceramics have become available (Biosorb®; Aesculap, Tuttlingen). During the first 12 months of a prospective clinical trial, Biosorb® products were implanted in 21 patients. The ceramics were used in a variety of clinical settings, ranging from pelvic osteotomies in children (n=9), to filling of bone cysts or osseous defects (n=4), to dorsal spondylodesis (n=6), as well as for the grafting of pseudarthroses (n=2). Average follow-up period was 13 (6–18) months.

The β-TCP granules, when used as part of a composite graft in combination with autologous bone, were completely resorbed after an average period of 14 weeks, while the cubes required 12 to 15 months. The more massive wedges have shown only a decrease in size and radio density. Due to the ability of the cubes and wedges to bear loads of up to 30 MPa, they were successfully implanted during pelvic osteotomies to augment or completely replace the bicortical grafts. Complications or foreign body reactions were not noted. The osseointegration was found to be favorable for all forms.

In light of the problems associated with autologous and allogeneic grafts, the use of synthetic bone substitutes will continue to increase. The combination of complete resorption, lack of risk of infection, and load sharing ability make the β-tricalcium phosphate implants a valuable addition to the spectrum of bone replacement products presently available. Their use in pediatric orthopedics could help avoid donor site morbidity including contour changes or growth disturbances, while providing a more stable graft. During the first phase of a prospective clinical trial, we have come to the conclusion, that the β-tricalcium phosphate ceramics represent a real alternative to other bone substitutes.