What Are Practical Surgical Anatomic Landmarks and Distances from Relevant Neurologic Landmarks in Cadavers for the Posterior Approach in Shoulder Arthroplasty?

BACKGROUND: Traditional total shoulder arthroplasty is performed through the deltopectoral approach and includes subscapularis release and repair. Subscapularis nonhealing or dysfunction may leave patients with persistent pain, impairment, and instability. Alternative approaches that spare the subscapularis include rotator interval and posterior shoulder approaches; however, to our knowledge, a cadaveric study describing pertinent surgical anatomy for a posterior shoulder approach regarding shoulder arthroplasty has not been performed. QUESTIONS/PURPOSES: (1) What are the distances from important neurologic structures of the shoulder for arthroplasty through a posterior approach? (2) What surgical landmarks can help identify the internervous interval between the infraspinatus and teres minor? METHODS: Twelve hemitorso cadaver specimens with intact rotator cuffs were dissected to study posterior shoulder anatomy regarding posterior shoulder arthroplasty. The median (range) age of the specimens was 79 years (55 to 92). Six of the 12 specimens were right-hand dominant, and 10 specimens were male. Cadaver height was a median 171 cm (155 to 191) and weight was a median of 68 kg (59 to 125). A posterior deltoid split and internervous approach between the infraspinatus and teres minor were used. A posterior T capsulotomy was performed. The distances to important neurologic structures were measured with an electronic caliper and provided in median (range) distances in millimeters. Although not as meaningful as distance ratios accounting for a specimen's body size, neurologic distances in millimeters are surgically practical and provide intraoperative usefulness. Surgical landmarks that can help identify the infraspinatus and teres minor plane were noted. Practical visual and tactile cues between the infraspinatus and teres minor were identified. Posterior rotator cuff tendon morphologies and widths were recorded. RESULTS: The closest important neurologic structure was the axillary nerve, measuring a median (range) 17 mm (9 to 19) from the inferior glenoid rim while the infraspinatus branch of the suprascapular nerve measured 21 mm (15 to 36) from the posterior glenoid rim. The axillary nerve measured 84 mm (70 to 97) from the posterior tip of the acromion in the deltoid split. Three surgical landmarks were helpful for identifying the plane between the infraspinatus and teres minor in all 12 specimens: (1) identifying the triangular teres minor tendon insertion, (2) medial palpation identifying the low point between the prominent muscle bellies of the infraspinatus and teres minor, and (3) identifying the distinct and prominent teres minor tubercle, which is well localized and palpable. CONCLUSION: A major benefit of the posterior approach for shoulder arthroplasty is subscapularis preservation. Multiple practical surgical cues are consistently present and can help identify the infraspinatus and teres minor interval. We did not find the presence of fat stripes to be helpful. The suprascapular nerve is in proximity to posterior surgical dissection and differs from the deltopectoral approach. This is an important distinction from an anterior approach and requires care with dissection. Future studies are necessary to assess iatrogenic risk to the posterior rotator cuff and external rotation strength. This may entail intraoperative nerve conduction studies of the posterior rotator cuff and clinical studies assessing external rotation strength. CLINICAL RELEVANCE: Studying posterior shoulder anatomy is an initial first step to assessing the feasibility of the posterior approach for anatomic shoulder arthroplasty. Additional studies assessing the degree of glenohumeral exposure and possible iatrogenic posterior rotator cuff injury are necessary. Because of the proximity of neurologic structures, it is recommended that surgeons not perform this technique until sufficient evidence indicates that it is equivalent or superior to standard anterior approach total shoulder arthroplasty. After such evidence is available, proper training will be necessary to ensure safe use of the posterior shoulder approach.

Posterior approach shoulder arthroplasty: a cadaveric study assessing access.

BACKGROUND: Posterior shoulder arthroplasty is an approach to shoulder replacement. The goal of this cadaveric study was to determine anatomic feasibility for posterior approach shoulder arthroplasty by evaluating access to the glenoid, humerus, and canal. METHODS: Twelve fresh frozen shoulders (10 males; 2 females) (mean age, 76 [range, 55-92 years]; weight, 79 kg [range, 34-125 kg]) were used. Traditional exposure techniques and retractors were used to evaluate direct access. Exposure to the glenoid and humerus was evaluated using digital imaging software. Successful placement from stemmed arthroplasty was evaluated using digital radiographs and imaging software. RESULTS: The posterior approach permitted direct access to 88.8% ± 8.1% of the glenoid. There was access to the center of the humeral head cut surface in 12 of 12 specimens. In 10 specimens, there was 100% access to the entire cut surface of the humerus and peripheral edges. The average access to the humerus was 95.3% ± 13.4%. Average angulation with stem placement was 0.73° of varus (range, 4.4° of varus to 3.5° of valgus). Regarding lateral plane angulation, there was an average of 0.33° of posterior angulation (range, 3.3° of posterior angulation to 2.5° of anterior angulation). CONCLUSION: Access to the center of the glenoid and humerus was achieved in all cases. More research is needed to evaluate the clinical efficacy of posterior shoulder arthroplasty, including mid- and long-term outcome and safety studies.

In Vivo Measurement of Rotator Cuff Tear Tension: Medial Versus Lateral Footprint Position.

We conducted a study to evaluate in vivo tension applied to the rotator cuff tendon positioned at the medial versus lateral footprint during arthroscopic rotator cuff repair. We evaluated 20 consecutive patients who underwent arthroscopic rotator cuff repair. During repair, a grasper was inserted through a lateral portal, and a digital weigh scale was attached. The tendon was grasped and translated to the medial footprint, and tension recorded. After a relaxation period, the tendon edge was translated to the lateral footprint, and tension recorded. Mean (SD) tension was 0.41 (0.33) pound when tendons were positioned at the medial footprint and 2.21 (1.20) pounds when they were positioned at the lateral footprint, representing a 5.4-fold difference (P < .0001). For smaller tears (≤ 20 mm anterior-posterior), 7.6 times less tension was applied to the tendons when pulled to the medial versus lateral footprint. For larger tears, 4.1 times less tension was applied to the tendons when pulled to the medial versus lateral footprint. This study demonstrated a significant, 5.4-fold increase in tension when the tendon edge was reduced to the lateral as opposed to the medial footprint in vivo.

Arthroscopic posterior stabilization and anterior capsular plication for recurrent posterior glenohumeral instability.

PURPOSE: The purpose of this study was to evaluate the outcomes and identify predictors of success for arthroscopic posterior Bankart reconstruction with modern suture anchor repair and anterior capsulolabral plication in a well-defined patient population-recurrent, traumatic, involuntary, unidirectional posterior shoulder instability. METHODS: Patients with recurrent, traumatic, involuntary, unidirectional posterior shoulder instability who underwent arthroscopic repair with a minimum of 2 years' follow-up were identified and evaluated retrospectively with outcome measures in the form of objective and subjective scores. Statistical analysis was performed to identify predictors of success with significance set at .05. RESULTS: Twenty-nine consecutive patients with a mean age of 26.3 years underwent posterior reconstruction and anterior balancing capsulolabral plication as needed with a mean follow-up of 5.5 years. Outcome scores averaged as follows: American Shoulder and Elbow Surgeons, 90.7; University of California, Los Angeles, 32.6; Simple Shoulder Test, 11.7; and Western Ontario Shoulder Instability, 82.9% of normal. Recurrent instability occurred in 3.4% of patients, 84.6% returned to sports, and 96.6% of patients believed surgery was successful and worthwhile. Patients who were younger (<30 years) or patients with more extensive pathology who required additional surgical procedures or received supplemental anterior plication sutures had less reliable or worse outcomes (P < or = .041). CONCLUSIONS: In a traumatic patient population with involuntary, unidirectional posterior shoulder instability, modern suture anchor repair of posterior labral lesions is effective and provides reliable outcomes. Younger patients and patients with worse pathology who required additional procedures had less reliable outcomes. Patients with supplemental anterior plication had more postoperative pain, and this adjunctive procedure may not be necessary for traumatic posterior labral tear surgery. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Acromioclavicular and sternoclavicular injuries and clavicular, glenoid, and scapular fractures.

Injuries to the acromioclavicular joint and the sternoclavicular joint and fractures of the clavicle, glenoid, and scapula vary widely in incidence, treatment, and prognosis. The treatment for acromioclavicular joint and clavicle injuries, which are relatively common, has significantly evolved. Controversy exists regarding the ideal treatment of type III acromioclavicular separations, whereas significant research has shown many potential benefits for surgically treating significantly displaced midshaft clavicle fractures that had traditionally been treated nonsurgically. Sternoclavicular injuries and scapula fractures are less common but are associated with high-energy mechanisms of injury and are potentially life threatening. Most of these injuries can be treated conservatively, although some injuries will benefit from surgical fixation. Identifying floating shoulders or unstable glenoid neck fractures without bony or ligamentous stabilization requires an understanding of the multiple anatomic stabilizers of the glenoid. Floating shoulders, glenoid neck fractures with 1 cm or 40 degrees or more of displacement, and intra-articular glenoid fractures with associated glenohumeral instability or intra-articular displacement of 5 mm or more may require surgical repair.

Patterns of pediatric supracondylar humerus fractures.

PURPOSE: The Wilkins-modified Gartland classification of pediatric supracondylar humerus fractures does not consider coronal or sagittal obliquity. The purposes of our study were (1) to identify and describe fracture characteristics with unique properties and (2) to propose a fracture classification system that can be reproduced reliably. METHODS: We retrospectively studied 203 consecutive displaced pediatric extension-type supracondylar humerus fractures treated operatively from January 1998 to January 2003. Fracture characteristics (eg, coronal and sagittal obliquity, postoperative alignment), type of surgical treatment, outcome, and complications were assessed and analyzed statistically with Student t test and a receiver operating characteristic curve. Significance was defined as P < 0.05. We incorporated significant cutoff values for fracture obliquity into our classification scheme and tested the classification's interobserver and intraobserver reliability. RESULTS: We identified 4 coronal (typical transverse, medial oblique, lateral oblique, and high fractures) and 2 sagittal (low sagittal and high sagittal) subtypes with significantly different characteristics and outcome. Compared with fractures with coronal obliquity of less than 10 degrees, fractures with coronal obliquity of 10 degrees or greater were associated with significantly more comminution and rotational malunion. Compared with fractures with sagittal obliquity of less than 20 degrees, fractures with sagittal obliquity of 20 degrees or greater were associated with a significantly higher incidence of additional injuries and were more likely to result in extension malunion. Analysis of the interobserver and intraobserver reliability for our system identified correlation coefficients ranging from 0.772 to 0.907 and 0.860 to 0.899, respectively. CONCLUSIONS: Because pediatric extension-type supracondylar humerus fractures vary significantly in terms of characteristics, identification of sagittal oblique and coronal oblique angles may have an important role in surgical decision making and may impact outcomes.

Physical examination for partial tears of the biceps tendon.

BACKGROUND: The accuracy of the physical examination for tears of the long head of the biceps remains controversial. PURPOSE: The goals were 1) to characterize the occurrence of partial tears of the long head of the biceps tendon in a group of consecutive patients, and 2) to analyze the diagnostic value of various clinical tests for pathologic lesions of the proximal biceps tendon. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Of 847 consecutive patients who underwent arthroscopic procedures for a variety of shoulder conditions, 40 were found at the time of arthroscopy to have partial biceps tendon tears. The average age of these 24 men and 16 women was 59 years (range, 18-83). Preoperative physical examinations had included 9 commonly used tests for shoulder examination. Statistical analysis included sensitivity, specificity, negative predictive value, positive predictive value, and likelihood ratios for these tests. RESULTS: The prevalence rate of partial tears was 5% (40/847) of all arthroscopic procedures. The most commonly associated conditions included rotator cuff tears (85% [34/40]) and anterior instability (7.5% [3/40]). Tenderness on palpation of the long head of the biceps tendon had a sensitivity of 53%, a specificity of 54%, and a likelihood ratio of 1.13. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratios for Speed's test were 50%, 67%, 8%, 96%, and 1.51, respectively. CONCLUSION: In patients with rotator cuff abnormality, the diagnosis of partial biceps tears cannot be made reliably with existing physical examination tests. Diagnostic arthroscopy is recommended, if clinically indicated, for potential partial tears of the long head of the biceps tendon. The treating physician should be prepared to treat unsuspected tears of the long head of the biceps tendon at the time of surgery.

Physical examination and imaging of the lateral collateral ligament and posterolateral corner of the knee.

Diagnosis of posterolateral corner injuries can be challenging. Understanding the mechanism of injury in combination with careful history taking and a thorough physical examination are crucial. Clinical findings may be subtle, especially in the acute setting. Specialized tests such as external rotation recurvatum test, posterolateral drawer test, reverse pivot shift test, and dial test are particularly helpful. A characteristic radiographic finding is the arcuate sign, whereas medial Segond fractures can be associated with posterolateral corner injuries. Magnetic resonance imaging is most useful when performed with a high strength magnet utilizing a coronal oblique technique. Prompt and accurate diagnosis of posterolateral corner injuries allows the orthopedist to initiate the appropriate repair and reconstruction procedures to assure optimum treatment results.

Proximity of the popliteal artery to the PCL during simulated knee arthroscopy: implications for establishing the posterior trans-septal portal.

This study defines the sagittal distance from the posterior cruciate ligament (PCL) to the popliteal artery under simulated arthroscopic conditions. This information is relevant for posterior knee arthroscopy, particularly for the safe establishment of the posterior trans-septal portal. Measurements from the PCL to the popliteal artery were made on sagittal magnetic resonance images obtained in a previous study of 10 fresh-frozen cadaveric knees. The mean sagittal distance from the mid-PCL to the popliteal artery was 29.1 +/- 11 mm (range: 18-55 mm). The mean sagittal distance from the proximal PCL fovea to the popliteal artery was 9.7 +/- 5 mm (range: 3-16 mm). The results of this study provide the arthroscopist working in the posterior compartments of the knee with a more detailed knowledge of the anatomic relationship between the PCL and popliteal artery. This knowledge will help minimize the risk of iatrogenic vascular injury during arthroscopic knee surgery.