Inhibition of inducible nitric oxide synthase promotes recovery of motor function in rats after sciatic nerve ischemia and reperfusion.

PURPOSE: To investigate the effects of inhibition of inducible nitric oxide synthase (iNOS) on the recovery of motor function in the rat sciatic nerve after ischemia and reperfusion injury. METHODS: A 10-mm segment of the sciatic nerve from 169 rats had 2 hours of ischemia followed by up to 42 days of reperfusion. The animals were divided into 2 groups that received either iNOS inhibitor 1400W or the same volume of sterile water subcutaneously. A walking track test was used to evaluate the motor functional recovery during reperfusion. Statistical analysis was performed for the measurements of the sciatic functional index (SFI) by using 2-way analysis of variance; 1-way analysis of variance was used for the post hoc analysis of specific values at each time point of the SFI measurement. RESULTS: 1400W-treated rats had earlier motor functional recovery than controls, with a significantly improved SFI between days 11 and 28. Histology showed less axonal degeneration and earlier regeneration of nerve fibers in the 1400W group than in the controls. Inducible NOS messenger RNA and protein were up-regulated during the first 3 days of reperfusion but there was a down-regulation of neuronal NOS and up-regulation of endothelial NOS in control animals. 1400W treatment attenuated the increase of iNOS but had no effect on neuronal NOS and endothelial NOS. CONCLUSIONS: Our results indicate that early inhibition of iNOS appears to be critical for reducing or preventing ischemia and reperfusion injury.

Medial or lateral dislocation (snapping) of a portion of the distal triceps: a biomechanical, anatomic explanation.

Medial and lateral snapping (dislocation) of the distal triceps over the epicondyle during elbow flexion has been reported but is frequently misdiagnosed and is not well understood. In this study a mathematical model was designed to simulate the effect that bony abnormalities at the distal humerus and soft tissue variations of the distal triceps have on the line of pull of the triceps. The predictions were then tested on prefabricated and fabricated plastic elbow models, as well as 8 cadaveric elbows. When the bony alignment was altered, varus angulation had the greatest effect: 30 degrees varus malalignment of the distal humerus displaced the centroid of the triceps vector medially by approximately 2.0 cm. Valgus malalignment had a lesser effect: 30 degrees valgus displaced it laterally by 1.5 cm. Negligible effects on the triceps line of pull were seen with internal or external malrotation and with flexion or extension malalignment. Of the soft tissue alterations, displacement of the triceps insertion had a greater effect than movement of the triceps origin. The triceps vector was displaced by approximately 70% of the amount of translation of the triceps insertion. The relationship between the triceps line of pull and the bony alignment is represented by the triceps (T) angle. Our use of the T angle to understand snapping triceps is analogous to the use of the quadriceps (Q) angle for patellar subluxation/dislocation. Treatment should aim to restore normal triceps biomechanics with soft tissue or bony procedures.

Stiffness of simulated radial neck fractures fixed with 4 different devices.

We performed a structural investigation of several fixation devices for radial head and neck fixation. Fourteen pairs of fresh-frozen human elbows were used to simulate unstable radial neck fractures fixed with each of the following plates: 2.0-mm T-plate, 2.0-mm blade plate, 2.7-mm T-plate, and 2.7-mm T-plate modified with a fixed-angle blade. The plate constructs were axially loaded in compression with a materials testing machine, and stiffness was calculated from a load-deformation curve. Through use of paired comparisons, the average stiffness of the modified 2.7-mm plate was found to be significantly greater than that of either 2.0-mm plate, whereas a trend was observed for increased stiffness of the modified 2.7-mm T-plate in comparison with the standard 2.7-mm T-plate. The results indicate that two important variables affecting construct stiffness are plate thickness and incorporation of a fixed-angle blade. Given these findings, the addition of a fixed blade to the 2.7-mm plate may improve the stability of fixation of comminuted radial neck fractures.

Macrodystrophia lipomatosa with associated fibrolipomatous hamartoma of the median nerve.

Macrodystrophia lipomatosa (MDL) is a rare disease typically causing localized gigantism and is often associated with a fibrolipomatous hamartoma (FH) of the median or plantar nerve. A previously unreported case of MDL with associated FH of the median nerve is presented.

Unrecognized dislocation of the medial portion of the triceps: another cause of failed ulnar nerve transposition.

OBJECT: Failed surgical treatment for ulnar neuropathy or neuritis due to dislocation of the ulnar nerve presents diagnostic and therapeutic challenges. The authors of this paper will establish unrecognized dislocation (snapping) of the medial portion of the triceps as a preventable cause of failed ulnar nerve transposition. METHODS: Fifteen patients had persistent, painful snapping at the medial elbow after ulnar nerve transposition, which had been performed for documented ulnar nerve dislocation with or without ulnar neuropathy. The snapping was caused by a previously unrecognized dislocation of the medial portion of triceps over the medial epicondyle. Seven of the 15 patients also had persistent ulnar nerve symptoms. The correct diagnosis of snapping triceps was delayed for an average of 22 months after the initial ulnar nerve transposition. An additional surgical procedure was performed in nine of the 15 cases and, in part, consisted of lateral transposition or excision of the offending snapping medial portion of the triceps. Of the four patients in this group who had persistent neurological symptoms, submuscular transposition was performed in the two with more severe symptoms and treatment of the triceps alone was performed in the two with milder neurological symptoms. Excellent results were achieved in all surgically treated patients. Six patients declined additional surgery and experienced persistent snapping and/or ulnar nerve symptoms. CONCLUSIONS: Failure to recognize that dislocation of both the medial portion of the triceps and the ulnar nerve can exist concurrently may result in persistent snapping, elbow pain, and even ulnar nerve symptoms after a technically successful ulnar nerve transposition.

Median nerve palsy presenting as absent elbow flexion: a result of a ruptured pectoralis major to biceps tendon transfer.

We describe a patient with a preexisting posttraumatic brachial plexopathy who had a complete high median nerve palsy due to rupture of the pectoralis major to biceps transfer near its distal insertion at the elbow region.

Cubitus varus associated with dislocation of both the medial portion of the triceps and the ulnar nerve.

Five patients with cubitus varus deformities from malunited childhood fractures had dislocation (snapping) of both the medial portion of the triceps and the ulnar nerve over the medial epicondyle. In addition to snapping, these patients had medial elbow pain or ulnar nerve symptoms. Cubitus varus shifts the line of pull of the triceps more medial, which can cause anteromedial displacement of the medial portion of the triceps during elbow flexion. The ulnar nerve is concomitantly pushed or pulled anteromedially by the triceps, and ulnar neuropathy may result from friction neuritis or from dynamic compression by the triceps against the epicondyle. Recognition of both the dislocating ulnar nerve and the snapping medial triceps is crucial in the successful treatment of this pathologic finding. In symptomatic individuals, we recommend either corrective valgus osteotomy of the distal humerus or partial excision or lateral transposition of the snapping medial triceps, or a combination of both. Alternatively, medial epicondylectomy can also eliminate the snapping. Transposition of the ulnar nerve can be performed for ulnar nerve symptoms and/or ulnar nerve instability. Using this approach, correction of the snapping and/or ulnar nerve symptoms was achieved in all cases.

Snapping of the triceps tendon over the lateral epicondyle.

We present a patient with translocation (snapping) of a portion of the triceps over the lateral epicondyle with elbow flexion. This condition is in many ways analogous to its counterpart at the medial aspect of the elbow, snapping of the medial head of the triceps, a clinical entity that is being increasingly recognized.

Episodic snapping of the medial head of the triceps due to weightlifting.

We describe two patients who had episodic elbow snapping and ulnar nerve dysesthesias only after weightlifting. These symptoms would disappear soon afterward. The episodic nature of their complaints and findings led to misdiagnosis. We documented by repeated clinical examinations and magnetic resonance imaging that the presence of these symptoms correlated directly with the finding of intermittent, activity-related snapping of the medial triceps. In both patients, the symptoms disappeared when the medial portion of the triceps migrated medially but did not dislocate over the medial epicondyle with elbow flexion. Thus, a minor change in the configuration of the medial portion of the triceps (fluid accumulation) in the same individual at different times can cause intermittent dislocation of the medial triceps. Previous papers dealing with patients with snapping of the medial triceps describe symptoms exacerbated by athletic activities, but the constant finding of snapping on sequential examinations.

Snapping of the medial head of the triceps and recurrent dislocation of the ulnar nerve. Anatomical and dynamic factors.

We describe seventeen patients (twenty-two limbs) who had snapping (dislocation) of both the ulnar nerve and the medial head of the triceps over the medial epicondyle. Two patients (two limbs) were seen because of painless snapping, four patients (five limbs) had snapping and pain in the medial aspect of the elbow, three patients (three limbs) had symptoms related to the ulnar nerve only, and six patients (seven limbs) had snapping and symptoms related to the ulnar nerve. In addition, snapping was identified incidentally on routine screening in five asymptomatic limbs in four patients, one of whom was seen because of snapping and symptoms related to the ulnar nerve on the contralateral side. The diagnosis was confirmed with magnetic resonance imaging or computerized tomography, or both, in all but the first three patients, in whom the operative findings were confirmatory. Only six patients (seven limbs) were sufficiently symptomatic to be managed operatively. Of these six patients, five (six limbs) who had symptoms related to the ulnar nerve had lateral transposition or excision of the dislocating medial head of the triceps in addition to decompression and transposition of the ulnar nerve. Two of these patients had had persistent symptoms immediately after a previous transfer of the ulnar nerve performed at another institution for symptoms related to, and well documented dislocation of, the ulnar nerve; we performed the index procedure to correct the postoperative snapping, which was the result of an unrecognized dislocation of the medial head of the triceps in one patient and the result of an accessory triceps tendon in the other. One patient who had pain in the medial part of the elbow, snapping (without symptoms related to the ulnar nerve), and cubitus varus had a valgus osteotomy of the distal aspect of the humerus that corrected the line of pull of the triceps and relieved the snapping. All of the patients who were managed operatively had an excellent result (no snapping, no symptoms related to the ulnar nerve, and a full range of motion), at an average of 4.5 years postoperatively. Non-operative treatment provided control of symptoms related to the ulnar nerve in four limbs and control of pain from the snapping in four limbs. Snapping on the medial side of the elbow, even if it is associated with symptoms related to the ulnar nerve, is not necessarily caused by dislocation of the ulnar nerve alone. Patients who have a transposition of the ulnar nerve, especially those who have dislocation of the ulnar nerve, should be examined intraoperatively with the elbow in flexion and extension so that the surgeon can be certain that the medial head of the triceps does not snap over the medial epicondyle. Failure to recognize concurrent dislocation of the ulnar nerve and the medial head of the triceps can result in persistent, symptomatic snapping after an otherwise successful transposition of the ulnar nerve.

Dislocating medial triceps and ulnar neuropathy in three generations of one family.

Variations in the medial triceps in conjunction with bilateral ulnar neuropathy have been identified in three generations of one family also possessing the phenotype of Waardenburg syndrome (a rare autosomal-dominant disorder with clinical features including cochlear deafness, dystopia canthorum, and pigmentation problems). To our knowledge, no other inherited condition with triceps anomalies has been reported. Study of this family provided insight into the relationship between dislocating medial triceps and ulnar neuropathy and demonstrated that a broad spectrum of clinical presentations exists-from being completely asymptomatic to producing symptomatic snapping and ulnar neuropathy.

Periprosthetic infections due to Mycobacterium tuberculosis in patients with no prior history of tuberculosis.

Although uncommon, infection of prostheses with Mycobacterium tuberculosis can be managed successfully if it is diagnosed early and treated correctly. A case of M. tuberculosis infection of a prosthetic knee first diagnosed 4.5 years after initial arthroplasty is described. This case and a review of the literature led to the conclusion that there are two distinct patterns of M. tuberculosis infection following joint implant surgery in patients without a history of tuberculosis. (1) Mycobacterium tuberculosis infection may be an unexpected finding at the time of arthroplasty. These patients generally have favorable outcomes using standard antituberculous chemotherapy, without implant removal. (2) Late-onset M. tuberculosis joint infection may be identified in patients with painful, clinically infected, or malfunctioning prostheses. In these cases, medical treatment alone is usually unsuccessful; prosthesis removal is often required. With recent increases in the incidence of tuberculosis in the United States and the emergence of multidrug-resistant strains of M. tuberculosis, periprosthetic tuberculous infection is likely to become more common.

Changes on magnetic resonance images after traumatic hip dislocation.

Fourteen patients with traumatic hip dislocation had serial magnetic resonance imaging and routine radiographic studies from the time of injury through 24 months after injury. One experienced radiologist interpreted all images prospectively for abnormalities suggesting osteonecrosis of the femoral head and posttraumatic arthritis. Eight hips demonstrated abnormal marrow signals on T1 and T2 weighted images within 6 weeks of injury. These changes progressed in 3 hips, and osteonecrosis was confirmed subsequently by plain radiography. The abnormal marrow signals in the remaining 5 hips proved to be transient, resolving on magnetic resonance images within 3 months in 4 of the 5 patients. Magnetic resonance imaging can be used with confidence for the early detection of osteonecrosis of the femoral head after traumatic hip dislocation or fracture-dislocation. The presence of acetabular or femoral shaft hardware did not preclude magnetic resonance imaging assessment of these patients when coronal, sagittal, and axial images were obtained. Magnetic resonance imaging was not reliable for assessing marrow changes within the first week after injury, nor was it helpful in predicting which patients were at risk for posttraumatic arthritis to develop. An algorithm is proposed for using magnetic resonance imaging in the early diagnosis of osteonecrosis of the femoral head after traumatic hip dislocation.

Results after replantation and revascularization in the upper extremity in children.

The rates of survival of the amputated part and the functional outcomes were studied retrospectively after seventy-three replantations and eighty-nine revascularizations in the upper extremity in 120 children. All operations were performed between January 1974 and December 1988 after partial and complete amputations at various levels. The ages of the patients ranged from three days to sixteen years. The average duration of follow-up was thirty-six months (range, fourteen months to seven years) for the patients who had had a replantation and thirty months (range, fourteen months to eight years) for the patients who had had a revascularization. The rate of survival of the amputated part was significantly higher (p < 0.0002) after revascularization (seventy-eight parts [88 per cent]) than after replantation (forty-six parts [63 per cent]). There was no association, for either group, between survival and the preoperative duration of ischemia, the level of the injury, the digit that had been injured, the number of arteries that had been repaired, or the use of venous grafts. The rate of survival after replantation of completely amputated parts was 72 per cent (twenty-eight of thirty-nine parts) when the amputation had resulted from a laceration injury and 53 per cent (eighteen of thirty-four parts) when the amputation had resulted from a crush or an avulsion injury. The rate of survival after revascularization of incompletely amputated parts was 100 per cent (all forty-five parts) when the injury had been the result of a laceration and 75 per cent (thirty-three of forty-four parts) when it had been the result of a crush or an avulsion. We did not find any relationship between the age of the patient and the rate of survival of the amputated part after revascularization; however, there was a significantly higher rate of survival (p , 0.02) after replantation in children who were less than nine years old (77 per cent [twenty-four of thirty-one parts]) compared with the rate in those who were nine to sixteen years old (52 per cent [twenty-two of forty-two parts]). The viability of the digit was in jeopardy after twenty-nine (40 per cent) of the seventy-three replantations and nineteen (21 per cent) of the eighty-nine revascularizations. Immediate reoperation resulted in the salvage of only two of the twenty-one replanted parts and six of the twelve revascularized parts that had a reoperation.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of immobilization on Achilles tendon healing in a rat model.

The aim of this study was to evaluate the effects of immobilization and mobilization on the functional and biomechanical recovery of injured Achilles tendons. Male Sprague-Dawley rats were allocated randomly into four groups: (a) sham operation, (b) division only (surgical transection of the Achilles tendon without immobilization), (c) "dummy" external fixation (division of the Achilles tendon and application of Kirschner wires), and (d) rigid external fixation (division of the Achilles tendon and immobilization with Kirschner wires connected by two triangular frames). All procedures were performed on the right lower limb; the left, uninjured, lower limb served as an internal control. Kirschner wires and external fixators were removed on day 12. Functional performance was determined from measurements of hind pawprints of rats walking preoperatively and on postoperative days 1, 3, 5, 7, 9, 11, 13, and 15. On day 15, the animals were killed and biomechanical evaluations were performed on both the injured and the uninjured Achilles tendon constructs. No functional or mechanical deficits were observed in the sham-operation group. Animals subjected to division of the Achilles tendon had an initial functional deficit that returned to near normal by day 15. The application of Kirschner wires was associated with an impairment of the functional performance of the rat as well as of the mechanical properties of the tendon-bone constructs. Immobilization by connection of the Kirschner wires to an external frame had an additional, highly significant (p < 0.001) detrimental effect on the functional and mechanical recovery of Achilles tendon-calcaneal complexes.

Shoulder pyarthrosis: a concomitant process.

Thirty cases of glenohumeral pyarthrosis are reported. Systemic immune compromise and local tissue abnormalities were each present in 74% of the adult patients. Both were present in 52%. Most adult patients were debilitated by chronic diseases. Diagnosis was frequently delayed due to mild symptoms and minimal, nonspecific laboratory findings. Poor results correlated with treatment delay. Shoulder pyarthrosis occurred ipsilateral to forearm arteriovenous dialysis fistulas in four patients. Postoperative shoulder pyarthroses were eradicated only in patients with clinically intact immune systems. Three patients (10%) with intact rotator cuffs had unsuspected associated subacromial bursa abscesses. Evaluation of suspected glenohumeral pyarthrosis should include evaluation of the subacromial bursa.

Achilles tendon injuries: a comparison of surgical repair versus no repair in a rat model.

Controversy exists regarding the treatment of Achilles tendon ruptures. The aim of this study was to determine whether surgical repair of the rat Achilles tendon offered any biomechanical, functional, or morphological advantage over no repair. Thirty-two male Sprague-Dawley rats were randomly allocated into four groups: (1) sham operated (skin incision only), (2) no repair (complete division of the Achilles tendon and plantaris tendon without repair), (3) internal splint (plantaris left intact), and (4) Achilles repair (with a modified Kessler-type suture). Functional performance was determined from the measurements of hindpaw prints utilizing the Achilles Functional Index. On day 15, the animals were killed, and biochemical and histological evaluations were performed on both the injured and uninjured Achilles tendon constructs. All groups subjected to Achilles tendon division had a significant initial functional impairment that gradually improved so that by day 15 there were no functional or failure load impairments in any group. The injured tendons in all three groups subjected to Achilles tendon division had a 13-fold increase in the cross-sectional area and were less stiff and more deformable than uninjured and sham-operated tendons on day 15 (P < .001). The magnitude of the biomechanical and morphological changes at postoperative day 15 and the initial impairment and rate of functional recovery were similar for no repair, internal splint, and Achilles repair groups. In summary, this study demonstrates that surgical repair of the Achilles tendon in the rat does not offer any advantage over nonoperative management.