Christopher M. Jobe

Posterior superior glenoid impingement: Expanded spectrum

Posterior superior glenoid impingement is a recently recognized mechanism of injury producing rotator cuff injury in athletes. Usually the mechanism is repetitive overhand activity such as throwing. A survey of the authors practice was undertaken to show a wider spectrum of this mechanism both in the activity that caused it and the number of structures at risk of injury from this mechanism. The survey revealed 11 patients who had a clear recollection of their mechanism of injury and an objective documentation of the injury by arthroscopy or imaging studies. The majority of shoulders had damage to more than one of the five structures at risk from this mechanism of injury. Six cases were not sports related. Glenoid impingement may injure one or more of the following: (1) superior labrum, (2) rotator cuff tendon, (3) greater tuberosity, (4) inferior glenohumeral ligament or labrum, and (5) superior glenoid bone. Injury to more than one structure may be the rule and injury to one structure may indicate investigation of the other four.

Painful athletic injuries of the shoulder.

Pain in the athletes shoulder is likely to have a mechanical origin, because the athlete performs repetitive high-stress activity. Proper treatment is based on understanding the biomechanics and physiology of the tissues, as well as the demands of the patients specific athletic activity. Correct rehabilitation is the key to successful conservative and surgical management. A return to previous activity depends on restoring the normal biomechanics, either through conservative management or surgery. Some of these problems are unsolved and remain fruitful areas for future research.

Superior glenoid impingement. Current concepts.

In the current decade impingement syndrome is becoming a less precise diagnostic entity. It is splitting into several categories of more exact diagnoses. The concept development, clinical picture, and currently recommended treatment of 1 of these entities, the superior glenoid impingement is reviewed. The complaint may be acute or chronic and may involve 1 or more of 5 structures: (1) superior labrum, (2) rotator cuff tendon, (3) inferior glenohumeral ligament, (4) greater tuberosity, and (5) the bony glenoid. The most commonly seen clinical entity is chronic dorsal shoulder pain in an athlete who throws with a positive relocation test. Treatment consists of strengthening of the cuff and scapular rotators. When there has been excessive inferior ligament stretch this must be augmented by anterior reconstruction.

Fixation of humeral prostheses and axial micromotion.

Surgeons often avoid cementing a proximal humeral prosthesis. Occasionally bony augmentation is needed. This study was undertaken to compare proximal cementation in combination with distal press with total cementation or press fit alone. In phase 1 axial micromotion with axial loading was measured in 15 pairs of humeri: 5 fully cemented versus proximally cemented, 5 fully cemented versus press fit, and 5 proximally cemented versus press fit. X-ray films of the specimens were obtained to assess canal fill. In phase 2 axial micromotion was measured in 5 pairs of high mineral density and 5 pairs of low mineral density to compare proximal cementation with press fit. The 3 M modular prosthesis was used in both phases. No difference was found in phase 1 among the 3 fixation techniques. A strong reverse statistical correlation (P = .007) (r = .55) was seen between axial micromotion and fill of the canal with the prosthesis. In the second phase no statistically significant difference was found between the techniques of fixation or between the 2 bone densities. Fill of the canal at the distal end of the prosthesis was the only variable found that affected axial micromotion, but it accounted for only approximately 30% of the variance. Bone quality and augmentation of the proximal bone with cement did not affect axial micromotion in this experiment but warrant further study.

The accuracy of the saline load test in the diagnosis of traumatic knee arthrotomies.

Objectives: When open joint injury is suspected in a knee laceration, the saline load test has been recommended as a diagnostic modality, especially in small wounds, where inspection and palpation cannot confirm joint violation. The goals of this study are: 1) to correlate fluid volume needed for positive diagnosis with demographic factors, 2) to assess the sensitivity of using the commonly recommended volume of 50 mL, and 3) to identify the minimum fluid volume necessary to obtain 95% sensitivity. Design: Prospective cohort. Setting: University medical center. Patients/Participants: Thirty consecutive patients scheduled for elective outpatient knee arthroscopy were prospectively enrolled. Exclusion criteria include history of open traumatic injury, presence of active infection, or limited range of motion as evidence of arthrofibrosis. Intervention: A standard lateral parapatellar portal was made with a no. 11 blade scalpel, and a 5.8 mm diameter cannula-trochar was inserted and withdrawn to create a standard arthrotomy size of 26.4 mm2. Using an 18-gauge needle, saline was injected through a separate lateral suprapatellar site until outflow was noted. Main Outcome Measurements: Upon fluid outflow, the volume of injected saline was recorded. Results: The volume injected until outflow was similar between men and women (P = 0.87). No correlation was observed between the volume injected and age (P = 0.85), height (P = 0.18), weight (P = 0.46), and body mass index (P = 0.91). Injection of 50 mL successfully identified only 46% of known arthrotomies. A saline load of 194 mL was required to achieve 95% sensitivity. Conclusions: For small lacerations around the knee, saline loads of less than 194 mL are of questionable sensitivity, and surgeons should not use the saline load test to rule out open knee injuries.

Spinal accessory nerve in a trapezius-splitting surgical approach

To elucidate the safe limits for muscle-splitting incisions of the trapezius muscle, 25 cadaver shoulders were studied. To describe the position of the nerve distances were expressed as a percentage of the distance from the tips of the vertebral spinous processes to the lateral tip of the acromion. The spinal accessory nerve was found to run a vertical course medial and parallel to the vertebral border of the scapula. Three to six nerve branches (average 3.8) also ran a vertical course lying between 33% to 50% of the distance from the tips of the vertebral spinous processes to the lateral tip of the acromion. The most lateral branch lay an average at 44% distance and never beyond 50%. Muscle-splitting incisions are relatively safe in the lateral 50% of the muscle. In the medial half they are to be avoided or pursued with great caution.

Damage to Cobalt-Chromium Surfaces During Arthroscopy of Total Knee Replacements

Background: It has been stated that care must be taken not to scratch the metal components during total knee arthroscopy; however, this concern has not been studied. Clinical observation during arthroscopy of total knee replacements suggested the possibility of damage to the femoral component by the arthroscopic cannula; therefore, a bench test was performed to study this potential risk. Methods: Cobalt-chromium femoral components were tested to determine the surface damage that resulted from moving a stainless-steel arthroscopic cannula and a plastic arthroscopic cannula across the components under a variety of applied loads. Scanning electron microscopy and surface-roughness measurements of the prosthetic surface were used to evaluate the damage. Results: The stainless-steel cannula produced observable alterations to the surface of the femoral component at loads as small as 8 N. The majority of these alterations were deposits of stainless steel from the cannula onto the component. The plastic cannula did not appear to produce alterations on the component surface. Surface roughness increased with increasing loading of the stainless-steel cannula, but there was no noticeable change with increasing loading of the plastic cannula. These forces did, however, severely damage some parts of the plastic cannula. Conclusions: Alterations to the surface of cobalt-chromium femoral components can occur during arthroscopy with stainless-steel cannulae but not with plastic cannulae. The results of this study support a recommendation to use plastic cannulae during arthroscopy of total knee replacements. Clinical Relevance: Arthroscopy of total knee replacements is increasing in the clinical setting, and damage to the prosthesis should be avoided whenever possible. This study provides evidence that damage to the femoral component is possible with a stainless-steel cannula and that use of a plastic cannula may reduce this risk.

Evaluation of the learning curve for reverse shoulder arthroplasty.

This purpose of this study was to quantify the surgical learning curve and provide guidelines to surgeons interested in teaching and performing reverse shoulder replacement. Sixty-two consecutive primary reverse shoulder replacements performed by a single surgeon were retrospectively reviewed. Using data from consecutive cases, surgical time was plotted against patient case order, and the linear regression slope was calculated. Case length slope analysis demonstrated a significantly negative slope with the first 18 cases, which subsequently leveled thereafter. The number of cases needed to arrive at this flat slope was defined as the proficiency point.The proficiency point was then verified using the measurable variables of baseplate screw number and glenosphere overhang by dividing the series into 2 groups: Group A included patients who had surgery prior to the proficiency point, and group B included patients who had surgery after the proficiency point. In group A, only 33% (6/18) had all 4 glenoid baseplate screws placed as compared to 66% (29/44) in group B (P=.02). Glenosphere overhang increased from a mean of 1.02 mm (+/-1.29 mm) in group A to 2.58 mm (+/-1.89 mm) in group B (P=.003).A learning curve of approximately 18 cases was found in this series based on the technical aspects of performing reverse shoulder replacement. This curve is likely even longer for lower volume shoulder surgeons. We recommend specialized training prior to performing this procedure.

Subdeltoid lipoma presenting as subluxation of the glenohumeral joint

This case illustrates that space-occupying lesions beneath the heavily collagenated portion of the deltoid can produce a confusing clinical picture mimicking subluxation. This patients clinical presentation was quite extraordinary in its resemblance to glenohumeral instability. The case also illustrates the importance of imaging studies in confirming questionable diagnoses. Such studies should be read by the surgeon, and any discrepancies from the radiologists reading should be addressed.

Removal of well-fixed flanged humeral prostheses may require humeral expansion

BACKGROUND A flanged humeral stem design can be advantageous in achieving an interlock between the prosthetic and bone interface leading to a long-term stable loading pattern. The purpose of this study is to report a short case series involving revision of a flanged humeral prosthesis. Our hypothesis was that a greater percentage of the flanged prostheses undergoing revision would require some form of bone expansion to achieve stem removal compared to the nonflanged. METHODS AND RESULTS In the period from October 2004 to July 2008, 43 patients underwent revision of a humeral prosthetic stem by a single surgeon. Of these, 6 prostheses were of a triflanged design. Of these six, five (83%) could not be removed with longitudinal force and required some expansion of the bone in order to achieve stem extraction. Of the nonflanged humeral stems, 3/37 (8%) required bone expansion to achieve extraction. Analysis of the 2 groups showed a statistical difference in the need for humeral expansion (P < .000001). CONCLUSIONS Surgeons preparing to revise a flanged humeral stem should include expansion of the humeral shaft, by episiotomy or windowing, as part of their preoperative planning and informed consent of the patient.