Aims

The aim of this study was to examine the implant accuracy of custom-made partial pelvis replacements (PPRs) in revision total hip arthroplasty (rTHA). Custom-made implants offer an option to achieve a reconstruction in cases with severe acetabular bone loss. By analyzing implant deviation in CT and radiograph imaging and correlating early clinical complications, we aimed to optimize the usage of custom-made implants.

Background: Calcaneonavicular coalitions (CNC) have been reported to be associated with anatomical aberrations of either the calcaneus and/or navicular bones. These morphological abnormalities may complicate accurate surgical resection. Three-dimensional analysis of spatial orientation and morphological characteristics may help in preoperative planning of resection.

Materials and Methods: Sixteen feet diagnosed with CNC were evaluated by means of 3D CT modeling. Three angles were defined that were expressed in relation to one reproducible landmark (lateral border of the calcaneus): the dorsoplantar inclination, anteroposterior inclination and socket angle. The contact surface area was determined from the depth and width of the coalitions. Three-dimensional reconstructions of the calcanei evaluated the presence and morphology of the anterior calcaneal facet and of a navicular beak. The inter-observer correlations were assessed for the accuracy of the measurement methods. Sixteen normal feet were used as controls for comparison of the socket angle and anatomy of the anterior calcaneal facet and of the navicular beak.

Results: The dorsoplantar inclination angle averaged 50° (±17), the anteroposterior inclination angle 64° (±15), and the pathologic socket angle 98° (±11). The average contact area was 156mm2. Ninety-four percent of all patients in the CNC group revealed a plantar navicular beak. In 50% of those patients the anterior calcaneal facet was replaced by the navicular portion and in 44% the facet was totally missing. In contrast, the socket angle in the control group averaged 77° (± 18), which was found to be statistically different than the CNC group (p=0.0004). Only 25% of the patients in the control group had a plantar navicular beak. Statistically significant inter-observer correlations were found for all measured angles.

Conclusions: Computer aided CT analysis and reconstructions help to determine the spatial orientations of CNC and provide useful information in order to anticipate morphological abnormalities of the calcaneus and navicular.

Introduction: Throughout known medical literature the proximal humeral fracture is mentioned with an approximately 5% contribution to all fractures. The optimal operative strategy regarding proximal humeral fractures is still being discussed controversely. This study was conducted to show implant associated problems and their clinical relevance.

Materials and methods: Of a total 198 patients with proximal humeral fractures 166 patients, 98 females and 68 males at a mean age of 74,7 years were treated operatively from 2000 to 2004 in our clinic with an angle-stabile plate osteosynthesis and underwent a clinical and radiological follow-up. Retrospectively we characterised the fractures by using the most common classification of NEER and assessed the functional results with the CONSTANT score.

Results: The 166 evaluated patients with 8 cases of a type I fracture, 13 patients with type II fracture, 34 patients with type III fracture, 47 cases with type IV fracture, 42 patients with type V fracture and 22 cases with type VI were all operatively treated with an angle-stabile plate osteosynthesis. 142 patients underwent early assisted physical therapy. Of all assessed patients the average CONSTANT score was 79,7 points. Among the 8 patients with type I fracture the average CONSTANT score was 84,4 points, among the 13 patients with type II fracture it reached an average 87,4 points. The average score of the 34 patients with type III fracture was 78,8 points. The more complex fractures, according to NEER’s classification, reached average scores of 71,2 points among the 47 cases with type IV fractures, 69,8 points (42 patients, type V) and 61,6 points (22 patients, type VI). The presence of avascular necrosis of the humeral head in 18 cases resulted in a significantly worse functional outcome and therefore a lower average score of 48,1 points. For 36 patients the follow-up revealed intraarticular dislocation of the proximal locking screws which required operative revision in 15 cases.

Conclusion: Even in the complex proximal humeral fracture one can achieve good clinical results for the patients by using an angle-stabile plate osteosynthesis and therefore establishing a secure and rigid situation for an optimized consecutive physical therapy, especially in the elderly. To prevent from intraarticular screw placement the proximal locking screws should be chosen shorter, if possible, then initially measured.