Laxity of the elbow after experimental excision of the radial head and division of the medial collateral ligament. Efficacy of ligament repair and radial head prosthetic replacement: a cadaver study.

We studied the stabilising effect of prosthetic replacement of the radial head and repair of the medial collateral ligament (MCL) after excision of the radial head and section of the MCL in five cadaver elbows. Division of the MCL increased valgus angulation (mean 3.9 +/- 1.5 degrees) and internal rotatory laxity (mean 5.3 +/- 2.0 degrees). Subsequent excision of the radial head allowed additional valgus (mean 11.1 +/- 7.3 degrees) and internal rotatory laxity (mean 5.7 +/- 3.9 degrees). Isolated replacement of the radial head reduced valgus laxity to the level before excision of the head, while internal rotatory laxity was still greater (2.8 +/- 2.1 degrees). Isolated repair of the MCL corrected internal rotatory laxity, but a slight increase in valgus laxity remained (mean 0.7 +/- 0.6 degrees). Combined replacement of the head and repair of the MCL restored stability completely. We conclude that the radial head is a constraint secondary to the MCL for both valgus displacement and internal rotation. Isolated repair of the ligament is superior to isolated prosthetic replacement and may be sufficient to restore valgus and internal rotatory stability after excision of the radial head in MCL-deficient elbows.

Muscular performance and fatigue in primary hyperparathyroidism.

The purpose of this study was to evaluate changes in muscular strength and endurance, work capacity, and subjective fatigue following surgical treatment of primary hyperparathyroidism (pHPT), and to assess whether changes in muscular function were due to changes in activation of the muscles. A prospective consecutive study design was used, and patients surgically treated for nontoxic goiter served as controls. Nineteen female patients with mild to moderate pHPT and 20 controls were included. Maximal isometric handgrip and quadriceps strength, quadriceps endurance (intermittent stimulation), and quadriceps activation (superimposed twitch technique) were used for evaluation of muscular function. All patients were operated on successfully. Knee extension strength increased by 17 +/- 17% (mean +/- SD; p = 0.0004) in the patients, whereas no change was observed in the controls. The relative strength increase correlated positively to patient age at operation (r = 0.52, p = 0.02). Handgrip strength, quadriceps endurance, and general work capacity did not change in any group after operation. Subjective fatigue was preoperatively higher in patients than in controls (p = 0.01), and decreased postoperatively to the level of controls. In conclusion, women with pHPT increase knee extension force after parathyroidectomy as a result of increased force generation capacity of the muscle. If change in physical performance is a determinant for change in subjective fatigue in pHPT after operation, then change in strength of the quadriceps muscle seems to be of primary importance, whereas handgrip strength, muscular endurance, and work capacity do not seem to be important. The cause of the increasing strength benefit with increasing age at operation as found in this study needs further investigation.