[Single-compartment knee arthroplasty prosthesis and idiopathic necrosis of the medial tibia surface]. / Prothèse unicompartimentaire et nécrose idiopathique du plateau tibial interne.

PURPOSE OF THE STUDY: Idiopathic necrosis of the medial articular surface of the tibia is exceptional. Diagnosis is quite difficult and often made late. Among the different treatments proposed, we preferred single-compartment arthroplasty. MATERIAL AND METHODS: We report 8 cases in women with a mean age of 71.1 years. Diagnosis was suspected due to drug-resistant knee pain, particularly frequent at night, initially with radiographically normal knees. The first radiographic signs, seen 3 months after the onset of pain, were pathognomonic for osteonecrosis evidencing subchondral defects of the tibial surface with a dense peripheral rim and apparently "sequestered" in a notch. Bone scintigraphy evidenced intense uptake in the medial compartment. MRI confirmed the diagnosis evidencing a band of low intensity signals completely surrounding a sequestered zone reaching the cortical. This band was stable and irreversible. In 5 cases CT scan and in 3 cases tomography identified the width and height of the necrotic area that was limited to the medial compartment in all cases. All patients were treated with a single compartment implant. The diagnosis of necrosis was confirmed at pathology. RESULTS: At 4,6 years of mean follow up all patients had an excellent outcome, "forgetting" their knee. No lucent lines developed along the femoral or tibial implants. DISCUSSION: Necrosis of the medial articular surface of the tibia is exceptional and often diagnosed late by bone scintigraphy or MRI. Surgical treatment is usually based on tibial osteotomy for valgisation or a single or three-compartment prosthesis. In our 8 cases, the necrosis was limited to the medial compartment, warranting our therapeutic option.

[Compression of the posterior branch of the radial nerve. An unknown etiology of certain paralysis and certain refractory epicondylalgies]. / La compression de la branche postérieure du nerf radial. Une étiologie méconnue de certaines paralysies et de certaines épicondylalgies rebelles

In certain circumstances, compression of the posterior branch of the radial nerve (posterior interosseous nerve) may be caused either by transverse fibrous bands in front of the articular capsule of the elbow, by the anterior border of the 2nd radial, by Frohse's lugament or by the superficial part of supinator brevis. Such problems may be accentuated by repeated dorsal flexion movements of the wrist, with hyperextension of the elbow and above all in prosupination. Clinically, they may result in either complete paralysis (2 cases), or in a syndrome of refractory epicondylar pain with nerve involvement (4 cases). The approach described by the authors permits complete exploration of all the potential points of compression and good results were obtained in the five patients who underwent surgery.