Visuomotor Prediction Errors Modulate EEG Activity Over Parietal Cortex.

The parietal cortex is thought to be involved in visuomotor adaptation, yet it remains unclear whether it is specifically modulated by visuomotor prediction errors (i.e. PEs; mismatch between the predicted and actual visual consequences of the movement). One reason for this is that PEs tend to be associated with task errors, as well as changes in motor output and visual input, making them difficult to isolate. Here this issue is addressed using electroencephalography. A strategy (STR) condition, in which participants were instructed on how to counter a 45° visuomotor rotation, was compared to a condition in which participants had adapted to the rotation (POST). Both conditions were matched for task errors and movement kinematics, with the only difference being the presence of PEs in STR. Results revealed strong parietal modulations in current source density and low theta (2-4 Hz) power shortly after movement onset in STR vs. POST, followed by increased alpha/low beta (8-18 Hz) power during much of the post-movement period. Given recent evidence showing that feedforward and feedback information is respectively carried by theta and alpha/beta oscillations, the observed power modulations may reflect the bottom-up propagation of PEs and the top-down revision of predictions.

Arthroscopic treatment of instability attributable to capsular injury or laxity.

Among the many causes of shoulder instability are traumatic capsular injury associated with the Bankart lesion and capsular laxity as seen in multidirectional instability. Previously, open surgical procedures were the most commonly accepted surgical treatment of these disorders. However, because of the foresight of surgeons such as Richard Caspari, arthroscopy rapidly is becoming the surgical treatment of choice. Current studies have shown a 97% satisfactory outcome of arthroscopic Bankart repair. Similarly, the arthroscopic treatment of multidirectional instability has produced a 93% satisfactory outcome. These results parallel the gold standard open surgical techniques of the past and subsequently have led to a change in the treatment of shoulder instability.

Rotator cuff repairs in patients 62 years of age or older.

We retrospectively reviewed 105 consecutive patients aged 62 years and older who had undergone a repair of a rotator cuff tear to evaluate the efficacy of this surgery in patients in this age range. Six patients died, and 7 had less than 2 years of follow-up or were incapable of returning for examination. Ninety-two patients with 97 rotator cuff tears were re-examined. The average preoperative UCLA (University of California, Los Angeles) score was 12.9 (range 8 to 20), and the average postoperative score was 32.4 (range 12 to 35). Five patients (5%) had failure of the repair, accounting for the poor results. Severe complications included infection (1 patient) and brachial plexus stretch injury (1 patient). Four additional patients sustained minor complications, for an overall rate of 6%. Overall, 87% of patients had good or excellent results. Eight additional patients, while satisfied, were classified as fair. Of the 5 failures, 3 were revised to a satisfactory result. Thus 90 of the 92 patients in the study were satisfied with the result of the surgery at final follow-up. Rotator cuff repair in patients 62 years and older results in increased function, decreased pain, and satisfactory results.

Osteochondritis dissecans of the elbow.

Osteochondritis dissecans of the elbow remains a difficult problem to manage in the young athlete. Though the etiology is unclear, a definite association between overuse with repetitive microtraumatic insult and OCD has been established. Early detection and appropriate treatment can provide the best chance for preventing an unfavorable outcome. In many cases, conservative treatment regimens will provide complete resolution of symptoms, return of function, and full recovery, including return to sports participation. Surgical indications should be recognized, however, and surgical management carried out when warranted. Most authors treat unstable lesions primarily by excision of the fragment, accompanied by drilling or burring of the base of the lesion. Symptoms usually improve significantly, but approximately half of all patients will continue to experience chronic pain or limitation of elbow motion, highlighting the significance and severity of OCD of the elbow.

Arthrofibrosis and complications in arthroscopy of the elbow.

The authors offer concise procedural advice for arthroscopic treatment of flexion contractures of the elbow, bracketed by indications for treatment and recommendations regarding postoperative complications.

Arthroscopic capsulodesis of the lunotriquetral joint.

A case series consisting of 20 consecutive patients with persistent ulnar-sided mechanical wrist pain, lunotriquetral interosseous (LTIOL) ligament tears resulting in joint incongruity and increased laxity, and traumatic triangular fibrocartilage complex (TFCC) tears was reviewed. Each patient underwent an arthroscopic reduction and internal fixation (ARIF) of the lunotriquetral joint, arthroscopic disk-carpal (disklunate-ulnocapitate-disktriquetral, DL-UC-DT) ligament plication, and TFCC repair or débridement. There were 12 right wrists and 8 left wrists, of which 12 were dominant. The mean patient age was 33 years; 7 patients had workers' compensation claims and 2 had legal claims. Fourteen patients recalled a specific injury mechanism, such as hyperextension or rotation. The accompanying traumatic TFCC tears were peripheral in 15 and linear radial in 6 patients (one patient had concomitant peripheral and radial linear tears), and in 6 cases, the palmar ulnocarpal extrinsic ligaments were partially torn. The mean preoperative modified Mayo Wrist Score was 50, and at a mean of 3.1 years after surgery, the score had increased to 88. There were 13 excellent, 5 good, and 2 fair results. Four patients had complications, including transient tenderness along the extensor carpi ulnaris and persistent neuritis of a dorsal branch of the ulnar nerve. Overall wrist comfort and function, as indicated by the modified Mayo Wrist Scores, improved after arthroscopic stabilization of ulnar-sided wrist injuries (pinning of the lunotriquetral joint, disk-carpal ligament plication, and TFCC repair or débridement).

Posterolateral rotatory instability of the elbow.

Since its original description by O'Driscoll in 1991, PLRI is becoming increasingly recognized as a significant cause of elbow pathology. It is well documented that this problem results from an insufficiency of the radial ulnohumeral ligament and its related lateral structures, and that this insufficiency is usually the result of elbow trauma. Diagnosis has improved with the introduction of the PLRI test to identify the instability and advancing MR imaging capabilities of illustrating the injury. Whereas open reconstruction was previously the only definitive treatment, improving arthroscopic techniques provide a satisfactory alternative in stabilizing the elbow.

Arthroscopic repair of partial-thickness tears of the rotator cuff.

Management of partial-thickness tears of the rotator cuff should include consideration of tear size, tear depth, patient age and activity level, and tear etiology. We present an arthroscopic technique for repair of articular surface partial-thickness tears that may promote healing by closing the tendon side-to-side, placing the debrided tendon end in contact with an abraded humeral surface. By repairing selected partial-thickness tears, progression of the tear and the need for subsequent repair may be prevented. Our preliminary results in 28 patients are encouraging and suggest that this technique is a useful adjunct to tendon debridement for articular surface partial-thickness tears of the rotator cuff.

Laser-assisted capsulorrhaphy for multidirectional instability of the shoulder.

PURPOSE: The purpose of this study was to review the clinical results of laser-assisted capsulorrhaphy performed on 27 shoulders in 26 patients for multidirectional shoulder instability with minimum follow-up of 2 years. TYPE OF STUDY: Prospective case series. METHODS: Laser shrinkage was performed on the entire capsule. In patients in whom the rotator interval did not shrink, suture plication of this area was performed. All patients were evaluated with respect to the incidence of recurrent instability, need for reoperation, and ability to return to their previous level of activity or sports participation. In addition, all patients were rated as satisfactory or unsatisfactory using criteria established by Neer. RESULTS: Twenty-six of 27 shoulders (96%) remained stable and asymptomatic a minimum of 2 years after surgery. Of 14 athletes in the study group, 12 (86%) returned to their previous level of sports participation. CONCLUSION: Our results suggest that laser-assisted capsulorrhaphy is an effective treatment alternative for multidirectional instability.

Anterior superior instability with rotator cuff tearing: SLAC lesion.

Anterosuperior instability of the shoulder may occur from a variety of pathologic lesions. We describe a specific entity, the SLAC (superior labrum, anterior cuff) lesion that involves an association of anterior-superior labral tear with a partial supraspinatus tear. We retrospectively isolated a group of 40 patients with this lesion. The presenting complaints, physical examination findings, surgical findings, and results were isolated. Overhead activities were the most common etiology; load and shift instability testing and whipple rotator cuff testing were the most common physical examination findings. Surgical repair was successful in 37 of the 40 patients. The SLAC lesion is a definable clinical entity with predictable history, examination, surgical pathology, and satisfactory results from surgery.

Technical note: a "new" arthroscopic sliding knot.

Sliding knots are an essential element of arthroscopic shoulder surgery. The authors have been using a previously undescribed arthroscopic sliding knot with good clinical success. This knot has been used in arthroscopic rotator cuff repair, arthroscopic shoulder stabilization, and arthroscopic SLAP repair. The technique of this knot is illustrated.

Basics of elbow arthroscopy.

With more innovation in arthroscopic equipment and surgical technique, elbow arthroscopy will continue to evolve and new indications will emerge. Strict adherence to the principles outlined above will allow the use of arthroscopy to treat a variety of elbow disorders in a safe and effective manner.

The pain control infusion pump for postoperative pain control in shoulder surgery.

PURPOSE: This study was initiated to evaluate the effect of a pain control infusion catheter in managing postoperative pain. TYPE OF STUDY: In a prospective, randomized trial, 62 consecutive patients undergoing arthroscopic subacromial decompression had an indwelling pain control infusion catheter placed at the operative site. MATERIALS AND METHODS: Thirty-one patients received 0.25% bupivacaine and 31 patients received saline infusions, each at a constant rate of 2 mL per hour. Patients evaluated their pain by visual analog scale, and also tabulated the amount of narcotic and nonnarcotic medication used each day in the first week of surgery. RESULTS: There was a statistically significant difference in pain in all parameters tested in the bupivacaine group as compared with the saline control group (P <.05). CONCLUSIONS: The bupivacaine pain control infusion pump is an effective means of decreasing postoperative pain.

Angiotensin II stimulates endothelial vascular cell adhesion molecule-1 via nuclear factor-kappaB activation induced by intracellular oxidative stress.

The recruitment of monocytes via the endothelial expression of vascular cell adhesion molecule-1 (VCAM-1) is a key step in the formation of the initial lesion in atherosclerosis. Because angiotensin (Ang) II may be involved in this process, we investigated its role on the signaling cascade leading to VCAM-1 expression in endothelial cells. Ang II stimulates mRNA and protein expression of VCAM-1 in these cells via the AT(1) receptor. This effect was enhanced by N(G)-nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor, and blocked by pyrrolidinedithiocarbamate, an antioxidant molecule. Ang II activated the redox-sensitive transcription factor nuclear factor-kappaB and stimulated the degradation of both inhibitor of kappaB (IkappaB)alpha and IkappaBbeta with different kinetics. The degradation of IkappaBs induced by Ang II was not modified by incubation with exogenous superoxide dismutase and catalase, suggesting that this effect was not mediated by the extracellular production of O(2)(-). In contrast, rotenone and antimycin, 2 inhibitors of the mitochondrial respiratory chain, inhibited the Ang II-induced IkappaB degradation, showing that generation of reactive oxygen species in the mitochondria is involved on Ang II action. BXT-51702, a glutathione peroxidase mimic, inhibited the effect of Ang II, and aminotriazole, an inhibitor of catalase, enhanced it, suggesting a role for H(2)O(2) in IkappaB degradation. This is confirmed by experiments showing that Ang II stimulates the intracellular production of H(2)O(2) in endothelial cells. These results demonstrate that Ang II induced an intracellular oxidative stress in endothelial cells, which stimulates IkappaB degradation and nuclear factor-kappaB activation. This activation enhances the expression of VCAM-1 and probably other genes involved in the early stages of atherosclerosis.

Thermal versus suture treatment of symptomatic capsular laxity.

This article reviews the clinical results of unipolar thermal capsular shrinkage in 30 patients and compares that group to similar groups previously managed by laser-assisted capsulorrhaphy or by an arthroscopic capsular shift procedure. Patients were evaluated with respect to incidence of recurrent instability, the need for reoperation, and the ability to return to previous levels of activity or sports participation. Patients were rated as satisfactory or unsatisfactory based on criteria established by Neer. The results of this study suggest that thermal capsulorrhaphy with rotator interval plication is an effective treatment alternative for multidirectional instability, with results comparable to those previously reported with open and arthroscopic procedures.

Repair of the rotator cuff. Mini-open and arthroscopic repairs.

The repair of rotator cuff tears by traditional open subacromial decompression and rotator cuff tendon reapproximation has proved successful in restoring function and decreasing pain, but open rotator cuff repair has some inherent disadvantages. Postoperative detachment of the deltoid repair has been reported and results in significant morbidity. The open technique may also require a longer period of limited motion resulting in greater stiffness. Arthroscopically assisted mini-open repairs and, more recently, completely arthroscopic repairs of the rotator cuff have been developed and increasingly are being applied. Both techniques avoid detachment of the deltoid. The mini-open and arthroscopic approaches to rotator cuff repair have the added benefit of arthroscopic evaluation of the glenohumeral joint. The mini-open technique has the advantage of allowing the direct visualization of the cuff repair and allows surgeons to place the stitches in an open fashion, which is familiar to all surgeons. The mini-open technique also allows the placement of tension-absorbing stitches in the rare cases that they are needed. Mini-open techniques also allow the choice of bone anchors or osseous tunnels for fixation. The completely arthroscopic cuff repair has several potential advantages over the open and mini-open cuff repair techniques; first is the decreased disruption of the soft tissues, which may result in less scarring and adhesions. The procedure is the most cosmetically appealing of the techniques. Reduced postoperative pain is also cited as an advantage but has been demonstrated only in a single, nonrandomized study. Finally, if technical difficulties arise, the conversion to a mini-open repair can be done easily. In a few studies, arthroscopic cuff repair techniques have shown promise as an alternative to mini-open or open repair, but these results have been at the hands of a few surgeons who have extensive experience in arthroscopy of the shoulder. In contrast, the mini-open procedure requires modest arthroscopic skills and has a documented history of success. Nevertheless, arthroscopic rotator cuff repair is a viable and effective technique in the hands of surgeons with adequate skills, and this procedure is likely to become more commonly performed in the future as shoulder arthroscopic skills and instrumentation improve.

Nonabsorbable versus absorbable suture anchors for open Bankart repair. A prospective, randomized comparison.

Suture anchors facilitate the surgical repair of capsuloligamentous structures to bone. Bioabsorbable suture anchors, which obviate potential pitfalls in the periarticular use of permanent implants, have recently become available. We randomly assigned 40 patients to undergo modified Bankart shoulder repairs with either nonabsorbable or absorbable suture anchors. The patients had a history of recurrent traumatic anterior instability that had not improved with nonoperative management. The average patient age was 22 years (range, 17 to 46), and the average preoperative Rowe score was 47 points in the nonabsorbable anchor group and 47 points in the absorbable anchor group. Average postoperative Rowe scores were 96 and 93 points, respectively. There was one failed result in the nonabsorbable anchor group and two in the absorbable anchor group. No statistically significant subjective or objective differences were found at an average of 25 months postoperatively. Our results reveal that, in this application, bioabsorbable suture anchors are a viable option for the repair of soft tissue to bone.

Arthroscopic treatment of multidirectional instability.

Multidirectional instability of the shoulder, described by Neer and Foster, has been treated surgically with the inferior capsular shift procedure. The small number of reports on mid-term outcomes indicate that good to excellent results have been obtained in 75% to 100% of cases. Arthroscopic treatment of multidirectional instability has been previously described. The purpose of this study was to review the results of the arthroscopic capsular shift procedure with a minimum follow-up of 2 years. A retrospective study was performed on 25 patients who underwent an arthroscopic capsular shift performed with the transglenoid technique between January 1990 and December 1993. All patients had earlier not responded to an extensive course of physical therapy. Excluded from the study were patients who had undergone a previous arthroscopic capsular shift or any other procedure, arthroscopic or open, for the shoulder. Average patient age was 26.4 years. There were 20 male and 5 female patients. Sixteen of the affected shoulders involved the dominant extremity. All patients had a history of asymptomatic subluxation that slowly progressed to symptomatic subluxation. Eleven patients had a history of dislocation. Thirteen patients were athletes who were symptomatic in their chosen sport, whereas the other patients were symptomatic in activities of daily living. All patients were examined while they were under anesthesia and had positive results on the sulcus test in abduction with associated anterior instability, posterior instability, or both. Follow-up evaluation was performed with patient interview and examination. All 25 patients were available for follow-up, which occurred an average of 60 months (range 36 to 80 months) after operation. Three patients had episodes of instability after the operation. The average Bankart score was 95 (range of 50 to 100). All but 1 patient had regained full symmetric range of motion by follow-up. Twenty-one (88%) patients had a satisfactory result according to the Neer system. Results of treatment with the arthroscopic capsular shift procedure for multidirectional instability of the shoulder appear to be comparable to those of the open inferior capsular shift.

The role of arthroscopy in the diagnosis and management of cartilaginous lesions of the wrist.

Articular cartilage lesions in the wrist are common. Diagnosis of these lesions is difficult, and the decision to operate may not be clear. A meticulous history and physical examination allows an accurate diagnosis. Appropriate surgical intervention can be useful in alleviating symptoms and returning the patient to normal activities. The origin, diagnosis, and treatment of cartilaginous lesions of the wrist are discussed in this article.