Biomedical subjects
Publications and source records attributed to A H Jahnke.
Instability is an uncommon complication after shoulder arthroplasty. In this article, we review the literature, discuss causative factors, and outline treatment options for instability after arthroplasty of the shoulder.
The use of the arthroscope for shoulder instability has improved our understanding of normal and pathologic shoulder anatomy. We must emphasize, however, that the majority of shoulder problems can be accurately diagnosed with a thorough history and good physical examination. The arthroscope is helpful, however, to confirm a clinical diagnosis or assist in making a diagnosis in difficult or complex pathologic findings. Further, as our surgical techniques and understanding of shoulder instability improve, more pathologic entities about the shoulder become amenable to arthroscopic surgical procedures. We must emphasize that most of these arthroscopic procedures are technically demanding and significant learning curves exist. These procedures should be undertaken only by physicians who have excellent arthroscopic skills and are comfortable recognizing normal and pathologic arthroscopic anatomy of the shoulder.
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MR imaging has been shown to be accurate in the diagnosis of rotator cuff disruption and tear. Uncertainty remains about the significance of increased signal intensity in the critical zone of the supraspinatus tendon without visible disruption of tendon fibers and about the significance of other secondary findings commonly encountered with rotator cuff abnormalities, such as musculotendinous retraction or obliteration and fluid in the subacromial space. We evaluated proton density-weighted and T2-weighted coronal images (obtained on a 1.5-T superconductive MR imager) of 55 shoulders in 32 asymptomatic volunteers for signal intensity in the supraspinatus tendon, location of the musculotendinous junction, fluid in the subacromial-subdeltoid space, and appearance of the fat plane. In 89% of shoulders, the supraspinatus tendon showed focal, linear, or diffuse increased signal intensity with or without loss of the low-signal-intensity tendon margin on proton density-weighted images. None of these findings were confirmed on T2-weighted images. The musculotendinous junction was always located within an area 15 degrees medial to 30 degrees lateral to the highest point (12 o'clock) on the humeral head convexity. A peribursal fat plane was poorly defined or absent in 49%, and fluid in the subacromial-subdeltoid space was found in 20%. Increased signal intensity in the supraspinatus tendon on proton density-weighted images without a corresponding increase on T2-weighted images, the presence of small amounts of fluid in the subacromial space, and the lack of preservation of the subdeltoid fat plane are common findings in asymptomatic shoulders and by themselves are poor predictors of rotator cuff disease.
Eighty patients with unstable tibial diaphyseal fractures were treated by closed intramedullary nailing with Ender-type flexible pins. The majority of injuries occurred from falling while snow skiing. Sixty-six fractures were closed and 14 were open. Fifty-eight fractures involved the distal, 21 fractures the middle, and one fracture the proximal one third of the tibial shaft. The average time to roentgenographic union was 15.5 weeks (range, ten to 34 weeks) for closed and open Grade I and II fractures. The time to union in Grade III fractures was 50 weeks (range, 36-64 weeks). There were two nonunions and two delayed unions. Both nonunions occurred in Grade IIIA open shaft fractures. Intramedullary stabilization with flexible, Ender-type pins provides good control of unstable tibial shaft fractures. The use of pins with a smaller diameter (3.5 or 4 mm) allows the surgeon to place more pins across the fracture site. The use of multiple pins and packing the intramedullary canal may provide better rotational stability. The use of Ender-type pins for fixation of Type IIIA open tibial shaft fractures is contraindicated.
Thirty-two patients with clinical suspicion of shoulder instability were the subject of this assessment of MRI (1.5 T G. E. Signa) and its comparison with CT-arthrography (GE8800 and GE9800) of the shoulder. Twenty-seven patients had a final diagnosis established by arthroscopy and five by arthrotomy. The imaging examinations were interpreted independently by three radiologists blinded against history, surgical diagnosis and results of the compared test. The statistical analysis included ROC-curves, sensitivity, specificity and accuracy as well as predictive values. The significance of the comparative results was assessed by the McNemar Sign test. MRI showed significantly better diagnostic results in the evaluation of labral structures (sensitivity 85%, specificity 90%, accuracy 88%) and humeral head impression fractures (75, 82, 78 %). None of the tests were of sufficient diagnostic value to identify capsular abnormalities. CT and MRI results regarding the biceps tendon and loose bodies were similar, however, statistically not significant. MRI proved to be of high diagnostic value in the assessment of the unstable shoulder and compared favorably with CT-A.
Understanding the normal anatomy of the shoulder and its variations is important for the proper interpretation of MR images. This study was performed to describe variations in the normal labral-capsular complex as seen on MR images. MR images of 52 shoulders in 30 asymptomatic volunteers and 27 shoulders of symptomatic patients who had subsequent arthroscopy and/or reconstructive surgery were obtained with 1.5-T MR. The 52 scans of the asymptomatic group were reviewed by three radiologists in conference, and the assessment of labral shapes and capsular insertions was done by consensus. The 27 MR scans of the shoulders in the symptomatic group were reviewed by one radiologist before and after the asymptomatic cases were interpreted. Differences in these two interpretations were shown on receiver-operating-characteristic curves by using the results of subsequent arthroscopy and surgery as the gold standard. The anterior and posterior parts of the labra, respectively, varied in shape but showed several dominant features: triangular (45%, 73%), round (19%, 12%), cleaved (15%, 0%), notched (8%, 0%), flat (7%, 6%), and absent (6%, 8%). Most capsules inserted anteriorly on the labrum (47%) or glenoid rim (49%). All posterior insertions were on the labrum (100%). Intrinsic labral signal was noted on proton density-weighted images, but never on T2-weighted images. Receiver-operating-characteristic curves from interpretations of the symptomatic and clinical cases made before and after evaluation of the asymptomatic shoulders showed the interpretations improved considerably after scans of asymptomatic volunteers were studied. Our study reveals a wide variability in the MR appearance of the labral-capsular complex in asymptomatic shoulders.
Sixty-six brachial plexus palsies in 64 patients were retrospectively reviewed at the San Francisco Unit of the Shriners Hospital system in a 15-year period from 1973 to 1988. All patients were referred with persistent brachial plexus palsies caused by birth trauma. The distribution of palsies at birth included 34 upper palsies, three lower palsies, and 29 mixed (or global) palsies. At final follow-up, the distribution of palsies had shifted and included 42 upper palsies, 6 lower palsies, and 14 mixed (or global) palsies. One patient had a persistent flail upper extremity. Many previously documented obstetrical risk factors were confirmed. Time to resolution or plateau averaged 4.5 months (range 3 weeks to 18 months). Only two palsies (one patient) resolved completely with time.
Twenty-five patients with shoulder instability or shoulder pain of undetermined etiology were prospectively evaluated with magnetic resonance imaging and computerized arthrotomography. Actual lesions were determined by arthroscopy or at the time of open surgical repair. The images obtained were interpreted independently by three radiologists blinded to both surgical results and the results of previous diagnostic tests. Sensitivity, specificity, and accuracy were determined for each imaging technique for a variety of pathologic entities, including anterior and posterior labral abnormalities, capsular redundancy, biceps-labral complex abnormalities, humeral head (Hill-Sachs) impression lesions, and glenohumeral loose bodies. Analysis of imaging techniques also included construction of receiver operator curves for labral abnormalities. Magnetic resonance imaging showed better diagnostic results in the evaluation of glenoid labral and humeral head impression lesions (P < 0.05). Both imaging techniques were equally successful in identifying biceps-labral lesions and intraarticular loose bodies within the glenohumeral joint. Neither imaging technique was consistent in the evaluation of capsular redundancy. Receiver operator curve analysis confirmed that magnetic resonance imaging was the more accurate imaging study in evaluating anterior and posterior glenoid labral abnormalities.