[Mega-prostheses in revision knee arthroplasty]. / Megaprothesen in der Knierevision.

BACKGROUND: Due to a predicted increase in primary total knee arthroplasty (TKA), revision TKA will gain importance over the following years. Because the average age of patients receiving a TKA is decreasing the possible need for multiple revisions might increase as well. Despite efforts to minimize bone and soft tissue damage, the resulting bone and soft-tissue loss increases with each revision and will make the use of megaprostheses indispensable in the future. COMPLICATIONS: The implantation of a mega-prosthesis must be carefully considered and planned, since mega-prostheses in particular are associated with an increased risk of infection and loosening. Mechanical complications, patient-specific problems and periprosthetic infections can be either the cause for or the result of revision surgery of a mega-prosthesis. In the case of a complication, only a salvage procedure, namely an arthrodesis, amputation or-if necessary-the installation of a permanent fistula is commonly recommended.

Acetabular defect classification in times of 3D imaging and patient-specific treatment protocols.

Parallel to the rising number of revision hip procedures, an increasing number of complex periprosthetic osseous defects can be expected. Stable long-term fixation of the revision implant remains the ultimate goal of the surgical protocol. Within this context, an elaborate preoperative planning process including anticipation of the periacetabular defect form and size and analysis of the remaining supporting osseous elements are essential. However, detection and evaluation of periacetabular bone defects using an unsystematic analysis of plain anteroposterior radiographs of the pelvis is in many cases difficult. Therefore, periacetabular bone defect classification schemes such as the Paprosky system have been introduced that use standardized radiographic criteria to better anticipate the intraoperative reality. Recent studies were able to demonstrate that larger defects are often underestimated when using the Paprosky classification and that the intra- and interobserver reliability of the system is low. This makes it hard to compare results in terms of defects being studied. Novel software tools that are based on the analysis of CT data may provide an opportunity to overcome the limitations of native radiographic defect analysis. In the following article we discuss potential benefits of these novel instruments against the background of the obvious limitations of the currently used native radiographic defect analysis.

Extensor hallucis longus-transfer for tibialis anterior tendon rupture repair.

OBJECTIVE: Restore the function of the tibialis anterior muscle, which is responsible for dorsiflexion and inversion of the foot. INDICATIONS: Spontaneous or traumatic rupture of the tibialis anterior tendon. CONTRAINDICATIONS: Patients with multimorbidity or lack of functional demands. SURGICAL TECHNIQUE: Direct repair of the tibialis anterior tendon with fiber-wire suture and augmentation with extensor hallucis longus tendon, potentially in combination with reinsertion of the tibialis anterior tendon in the medial cuneiform. POSTOPERATIVE MANAGEMENT: Six weeks of non-weight-bearing: 3 weeks of cast immobilization with ankle in 10° dorsiflexion, followed by 3 weeks of splint immobilization and passive mobilization. Then stepwise increase in weight-bearing over a period of 2-3 weeks. RESULTS: In 8 patients postoperative results with a mean follow-up of 13.5 months were available. One patient showed a rerupture of the augmented tendon. The mean American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score was 81.0 (range 67-88). The median ankle dorsiflexion muscle strength was 67% (range 29.3-85.5%) compared to the nonoperated leg. All patients, except the one that experienced rerupture, were very satisfied or satisfied with the result.

The prevalence of vitamin D deficiency in patients with vertebral fragility fractures.

Hypovitaminosis D has been identified as a common risk factor for fragility fractures and poor fracture healing. Epidemiological data on vitamin D deficiency have been gathered in various populations, but the association between vertebral fragility fractures and hypovitaminosis D, especially in males, remains unclear. The purpose of this study was to evaluate serum levels of 25-hydroxyvitamin D (25-OH D) in patients presenting with vertebral fragility fractures and to determine whether patients with a vertebral fracture were at greater risk of hypovitaminosis D than a control population. Furthermore, we studied the seasonal variations in the serum vitamin D levels of tested patients in order to clarify the relationship between other known risk factors for osteoporosis and vitamin D levels. We measured the serum 25-OH D levels of 246 patients admitted with vertebral fractures (105 men, 141 female, mean age 69 years, sd 8.5), and in 392 orthopaedic patients with back pain and no fractures (219 men, 173 female, mean age 63 years, sd 11) to evaluate the prevalence of vitamin D insufficiency. Statistical analysis found a significant difference in vitamin D levels between patients with vertebral fragility fracture and the control group (p = 0.036). In addition, there was a significant main effect of the tested variables: obesity (p < 0.001), nicotine abuse (p = 0.002) and diabetes mellitus (p < 0.001). No statistical difference was found between vitamin D levels and gender (p = 0.34). Vitamin D insufficiency was shown to be a risk factor for vertebral fragility fractures in both men and women.