Osteonecrosis of the Upper Extremity: MRI-Based Zonal Patterns and Differential Diagnosis.

Regarding the upper extremity, osteonecrosis can relate to the humeral head and to any carpal bone, most commonly the lunate (Kienböck's disease), scaphoid (Preiser's disease and nonunion), and capitate bone (osteonecrosis of the capitate head). In children and adolescents, osteochondrosis is an important differential diagnosis at the epiphyses. Appropriate imaging of osteonecrosis depends on knowledge about blood supply, biomechanical load, and bone repair mechanisms. Contrast-enhanced MRI (ceMRI) enables the differentiation of up to three mostly band-shaped zones: necrotic tissue (proximal), hypervascular repair tissue (intermediate), and viable bone (distal). To distinguish between necrotic and repair zones, intravenous gadolinium is recommended in MRI. Osteosclerosis and insufficiency fractures in early and intermediate stages as well as osteoarthritis in advanced stages are best depicted using high-resolution CT (HRCT). The combination of HRCT and ceMRI allows for exact classification of osteonecrosis regarding morphology and viability.

[Scaphoid pseudarthrosis : Complex reconstruction using vascularized bone grafts]. / Skaphoidpseudarthrose : Komplexe Rekonstruktionen mithilfe vaskularisierter Knochentransplantate.

The most important goals of scaphoid reconstruction in pseudarthrosis are correction of the humpback deformity, the realignment of the proximal carpal row and the bony union of the scaphoid. Therefore, in most cases bone grafting is required. To increase the healing rate and to improve vascularization, several kinds of vascularized bone grafts have been developed. Pedicled grafts are preferably harvested from the dorsal or palmar side of the distal radius with fusion rates between 27% and 100%. Free microvascular grafts can be obtained from the iliac crest and the medial or lateral femoral condyle with fusion rates between 60% and 100%. For their application microsurgical equipment and skills are required. Up to now osteochondral grafts from the femoral condyle offer the only chance for joint surface replacement by transferring part of the surface of the femoropatellar joint. The use of vascularized grafts is still a matter of controversy, since their superiority is still unproven compared to nonvascularized grafts, which also achieved 100% fusion rates in several series. They are indicated in secondary procedures after failed reconstruction and nonunion with small avascular proximal pole fragments. Since no evidence-based guidelines exist, this article provides an experience-based treatment algorithm for scaphoid nonunion with special consideration to vascularized bone grafts.

[Brachioradialis rerouting for restoration of forearm supination or pronation]. / Rerouting des Musculus brachioradialis zur Verbesserung der Unterarmsupination oder -pronation.

OBJECTIVE: Improvement of active forearm supination or pronation. Reduction of paralytic pronation or supination posture. INDICATIONS: Disability or impairment of active supination or pronation due to cerebral palsy, obstetric palsy or traumatic brachial plexus palsy, quadriplegia or paralysis from other causes. CONTRAINDICATIONS: Inadequate passive range of motion of forearm supination or pronation. Insufficient power of brachioradialis muscle < M4. Insufficient rehabilitation after conservative treatment or neurosurgical intervention with possible improvement of supination or pronation. Lack of patient's cooperation and compliance. SURGICAL TECHNIQUE: Exposure and mobilisation of brachioradialis muscle. Division of brachioradialis tendon distally with Z-plasty. Passing distal tendon through the interosseus space in dorsal to palmar direction for restoration of supination respectively in palmar to dorsal direction for restoration of pronation. Suturing both tendon ends. POSTOPERATIVE MANAGEMENT: Management includes an above elbow cast with the elbow in 70° flexion for 4 weeks. Then active physiotherapy to learn new brachioradialis muscle function for supination or pronation over 1-1.5 years. If needed dynamic orthesis. RESULTS: Özkan et al. performed brachioradialis rerouting to restore supination in 5 children between 4 and 14 years with pronation deformity and to restore pronation in 4 children aged 5-9 years with supination deformity. Mean active gain for supination was 81° (40-140°). Active pronation improved from 28 to 49° (30-75°; Özkan et al., J Hand Surg Br 29:263-268, 2004; Özkan et al., J Hand Surg Am 29:22-27, 2004). Between April 2006 and January 2011 we used this technique in 4 patients aged 7-26 years (mean 14 years). Three patients could be followed up. One patient had preoperative a fixed pronation deformity of the forearm in 80° pronation. In this case active range of motion could be improved to 80/30/0° pronation/supination. One patient improved from preoperative 0/0/90° pronation/supination to 30/0/90° postoperatively. In one case no functional improvement of forearm rotation could be achieved in long-term follow-up. No functional loss in forearm rotation to the opposite direction or of the elbow function was observed. Mean follow-up time was 51 months (21-77 months).

[Early radiological diagnostics for scapholunate dissociation (SLD)]. / Radiologische Frühdiagnostik der skapholunären Dissoziation (SLD).

The partial tear of the scapholunate ligament (pre-dynamic stage of SLD) as well as the complete tear (dynamic stage) does not lead to carpal malalignment. However, if the completely ruptured ligament is accompanied by lesions of the extrinsic ligaments, both the scaphoid and the lunate are malaligned already at rest (static stage of SLD). Later, osteoarthritis will develop, beginning in the radioscaphoid compartment, progressing to the midcarpal joint, and ending in a carpal collapse (osteoarthrotic stage of SLD). Dynamic SLD is detectable only in stress views and in cinematography. The high utility of MRI for directly visualizing the injured ligament is emphasized: reparation tissue is focally enhanced at the rupture site by intravenously applied contrast agent; the individual segments of the scapholunate ligament can be visualized in direct MR arthrography, therefore allowing differentiation of partial and complete ligamentous tears.

[Scaphoid fracture and nonunion: current status of radiological diagnostics]. / Skaphoidfraktur und -pseudarthrose: Eine aktuelle Standortbestimmung der radiologischen Diagnostik.

Scaphoid fractures, which involve approximately two-thirds of all wrist injuries, are often not detected during initial radiographic examination. By using high-resolution CT and dedicated MRI, it is possible to recognize scaphoid fractures soon at the first diagnostic approach and to assess fragment stability. CT imaging provides all the relevant information of the fracture extent and of the fracture healing in the follow-up. MRI is most sensitive in the detection of scaphoid fractures; however, fracture signs must be differentiated from those of a bone bruise. Both the initially overseen scaphoid fracture and the unsuccessful healing can lead to the natural history of scaphoid nonunion. In the injured scaphoid, CT imaging is essential for depicting the osseous morphology, whereas contrast-enhanced MRI is crucial for assessing the viability of the proximal fragment.