Biomechanical Study of a Subscapularis Repair Technique for Total Shoulder Arthroplasty.

Secure subscapularis repair is an essential element of total shoulder arthroplasty. Some surgeons prefer subscapularis peel because of ease of use, but some evidence suggests that lesser tuberosity osteotomy provides better fixation. The authors developed a novel, through-implant repair technique and performed a biomechanical study of its strength with cadaveric specimens. The authors obtained 20 matched pairs of cadaveric shoulders and inserted an uncemented short-stemmed humeral prosthesis that facilitates through-implant repair in all specimens. For each cadaver, the subscapularis was repaired with lesser tuberosity osteotomy and standard suture technique on 1 side, and the contralateral subscapularis was repaired with a novel through-implant suture repair and subscapularis peel technique. Displacement of the subscapularis footprint, ultimate load to failure, and stiffness of each repair were measured and compared between fixation groups. Mean±SD displacement of the lesser tuberosity osteotomy group was 0.75±0.94 mm at 10 cycles and 2.24±2.76 mm at 500 cycles. Mean±SD load to failure was 612±185 N, and mean±SD ultimate stiffness was 119±32 N/mm. No significant differences were noted between the lesser tuberosity osteotomy group and the subscapularis peel group in mean±SD displacement at 10 cycles (1.09±1.30 mm, P=.31), mean±SD displacement at 500 cycles (2.85±2.43 mm, P=.26), mean±SD load to failure (683±274 N, P=.31), or mean±SD ultimate stiffness (117±37 N/mm, P=.88). In a biomechanical testing model, through-implant subscapularis repair provided secure fixation relative to currently accepted subscapularis repair techniques in total shoulder replacement. [Orthopedics. 2016; 39(5):e937-e943.].

Early Outcomes Following Metal-on-Metal Reverse Total Shoulder Arthroplasty in Patients Younger Than 50 Years.

Reverse total shoulder arthroplasty (TSA) is a useful intervention for older patients with glenohumeral arthritis and a deficient rotator cuff. However, as a semiconstrained prosthesis, conventional reverse TSA implanted in a young patient could fail over time secondary to polyethylene wear and subsequent osteolysis. A metal-on-metal prosthesis may avoid this type of failure. The purpose of this study is to assess the outcomes in an initial cohort of young patients who underwent reverse TSA using a metal-on-metal prosthesis. Surgical indications included age younger than 50 years with a functioning deltoid and significant impairment of shoulder function with irreparable rotator cuff due to tumor resection, arthritis, or revision surgery. Nine patients with an average age of 37 years underwent implantation of a custom metal-on-metal reverse TSA prosthesis. All patients had a minimum 12-month follow-up or a failure of their procedure requiring revision surgery prior to 1 year. American Shoulder and Elbow Surgeons (ASES) scores, Constant scores, and range of motion were recorded and analyzed pre- and postoperatively to assess improvement, and all complications were noted. Average ASES score improved from 47 points preoperatively to 73.4 points postoperatively (P=.013). Average Constant and adjusted Constant scores improved from 20.8 points and 16% preoperatively to 61.8 points and 67.3% postoperatively, respectively (P=.019 and P=.068). Mean postoperative active forward flexion and active external rotation were 119.4° and 10°, respectively. Complications included the following: 3 patients sustained a postoperative dislocation, 1 patient had a glenoid fracture and complete loss of fixation of the baseplate, and 1 patient experienced dissociation of the glenosphere from the base-plate. Although metal-on-metal reverse TSA may appear to be an attractive choice in the treatment of young patients with limited reconstructive options, postoperative outcomes are disappointing, and the complication rate is high. [Orthopedics.2016; 39(5):e957-e961.].

Proximal Biceps Tenodesis: An Anatomic Study and Comparison of the Accuracy of Arthroscopic and Open Techniques Using Interference Screws.

PURPOSE: To (1) better define the anatomy of the proximal shoulder in relation to the long head of the biceps tendon, (2) compare the length-tension relationship of the biceps tendon in the native shoulder with that after arthroscopic and open tenodesis techniques using interference screws, and (3) provide surgical recommendations for both procedures based on study findings. STUDY DESIGN: Descriptive laboratory study. METHODS: Twenty fresh-frozen cadaveric shoulders were dissected for analysis. Initial anatomic measurements involving the proximal long head of the biceps tendon (BT) were made, which included: the labral origin to the superior bicipital groove (LO-SBG), the total tendon length (TTL), the musculotendinous junction (MTJ) to the inferior pectoralis major tendon border, the MTJ to the superior pectoralis major tendon border, and the biceps tendon diameter (BTD) at 2 different tenodesis locations. These same measurements were made again after completing a simulated suprapectoral arthroscopic and open subpectoral tenodesis, both with interference screw fixation. Statistical comparisons were then made between the native anatomy and that after tenodesis, with the goal of assessing the accuracy of re-establishing the normal length-tension relationship of the long head of the BT after simulated arthroscopic suprapectoral and open subpectoral tenodesis with tenodesis screws. RESULTS: For all cadavers, the mean TTL was 104.1 mm. For the arthroscopic suprapectoral technique, the mean LO-SBG was 33.6 mm, and the mean tendon resection length was 12.8 mm in males and 5.0 mm in females. The mean BTD was 6.35 mm at the arthroscopic suprapectoral tenodesis site and 5.75 mm at the open subpectoral tenodesis site. Males were found to have statistically longer TTL and LO-SBG measurements (111.6 vs 96.5 mm [P = .027] and 37.2 vs 30.0 mm [P = .009], respectively). In the native shoulder, the mean distances from the MTJ to the superior and inferior borders of the pectoralis major tendon were 23.8 and 31.7 mm, respectively. No statistically significant differences were found in the location of the MTJ after simulated arthroscopic or open tenodesis with tenodesis screws as compared with the native shoulder. Mean hole depth in the open subpectoralis tenodesis was 22.4 mm (males) and 18.6 mm (females), with a mean of 20.5 mm for both sexes. CONCLUSION: This study better defines the anatomy of the proximal shoulder in relationship to the long head of the BT. Using our surgical techniques and recommendations, both arthroscopic and open tenodesis procedures adequately restored the native length-tension relationship of the long head of the biceps. Surgical recommendations are as follows: For arthroscopic suprapectoral tenodesis with tenodesis screws, the anatomic landmark of the SBG should be used. The tendon resection length should be approximately 1 cm in males and 5 mm in females when using a 25-mm tunnel. For subpectoral tenodesis, the site of tenodesis should be placed approximately 3 cm above the inferior border of the pectoralis major tendon in the bicipital groove; whipstitching and preserving approximately 2 cm of the biceps tendon above the MTJ is also recommended. The diameter of the screws in either location should be based on patient anatomy. However, this study shows the need for slightly longer screws for the subpectoral tenodesis, as the average hole depth was 20.5 mm. The system used in this study has 7 × 10-mm and 8 × 12-mm screws available. Based on study findings, a screw length of 15 to 18 mm may be needed.

Optimization of coded aperture radioscintigraphy for sentinel lymph node mapping.

PURPOSE: Radioscintigraphic imaging during sentinel lymph node (SLN) mapping could potentially improve localization; however, parallel-hole collimators have certain limitations. In this study, we explored the use of coded aperture (CA) collimators. PROCEDURES: Equations were derived for the six major dependent variables of CA collimators (i.e., masks) as a function of the ten major independent variables, and an optimized mask was fabricated. After validation, dual-modality CA and near-infrared (NIR) fluorescence SLN mapping were performed in pigs. RESULTS: Mask optimization required the judicious balance of competing dependent variables, resulting in sensitivity of 0.35%, XY resolution of 2.0 mm, and Z resolution of 4.2 mm at an 11.5-cm field of view. The findings in pigs suggested that NIR fluorescence imaging and CA radioscintigraphy could be complementary, but present difficult technical challenges. CONCLUSIONS: This study lays the foundation for using CA collimation for SLN mapping, and also exposes several problems that require further investigation.

Plating of acute humeral diaphyseal fractures through an anterior approach in multiple trauma patients.

OBJECTIVE: We evaluated the clinical and long-term functional outcomes of humeral diaphyseal fractures treated with acute anterior plating in a trauma population. DESIGN: Single-center, retrospective cohort analysis with long-term prospective follow-up. SETTING: Urban, Level I trauma center. PATIENTS: Ninety-six patients with high-energy fractures of the humeral shaft were treated over a 10-year period. INTERVENTION: All patients were treated by a standard surgical protocol of open reduction through an anterior approach with small or large fragment fixation in the supine position. MAIN OUTCOME MEASUREMENTS: Mechanism of injury, time to union, complications, and range of motion during clinical follow-up were obtained. We also prospectively assessed long-term strength, range of motion, and perceptions of disability using the Disabilities of the Arm, Shoulder and Hand questionnaire. RESULTS: Mean time to surgery was 5 days (standard deviation, 11 days); 97.5% of patients achieved union in an average of 16.9 weeks (range, 6-56 weeks). Complications included two postoperative infections, two nonunions, and three implant failures. Long-term follow-up (n = 34) averaged 4.75 years (range, 1.4-10.8 years). On average, no significant differences between the injured and uninjured extremities were seen in range of motion at the shoulder and elbow with the exception of shoulder flexion. A modest loss of upper extremity strength in the injured arm was appreciated. The mean Disabilities of the Arm, Shoulder and Hand score was 25.9 (range, 0-79). CONCLUSIONS: A standard anterior surgical approach with small fragment fixation is a safe and effective treatment for humeral shaft fractures in multiple trauma patients. We show a high union rate and few complications, although a modest loss of function and some perceived disability exists in the long-term.

Sub-millimeter technetium-99m calibration sources.

PURPOSE: Small animal radioscintigraphic imaging systems aim to achieve sub-millimeter resolution. At the present time, sub-millimeter calibration sources that can be placed at will within an imaged volume are not readily available. We have developed a method for producing technetium-99m (Tc-99m) sources in less than 15 minutes with readily available reagents. PROCEDURES: Tc-99m pertechnetate [TcO(4)](-) was incubated with 45 microm to 106 microm diameter spherical anion exchange beads, washed, and mounted as desired for instrument calibration. RESULTS: The procedure yields spherical sources having between 6.8 microCi to 11.1 microCi of Tc-99m per source. This work shows that dual imaging of these sources using white light and radioscintigraphy permits measurement of system performance with high precision. CONCLUSION: Easily prepared, sub-millimeter Tc-99m spherical calibration sources are described, and it is demonstrated that such sources are useful for measuring the resolution and sensitivity of radioscintigraphic systems, such as those designed for small animal imaging.

Coded aperture nuclear scintigraphy: a novel small animal imaging technique.

We introduce and demonstrate the utility of coded aperture (CA) nuclear scintigraphy for imaging small animals. CA imaging uses multiple pinholes in a carefully designed mask pattern, mounted on a conventional gamma camera. System performance was assessed using point sources and phantoms, while several animal experiments were performed to test the usefulness of the imaging system in vivo, with commonly used radiopharmaceuticals. The sensitivity of the CA system for 99mTc was 4.2 x 10(3) cps/Bq (9400 cpm/microCi), compared to 4.4 x 10(4) cps/Bq (990 cpm/microCi) for a conventional collimator system. The system resolution was 1.7 mm, as compared to 4-6 mm for the conventional imaging system (using a high-sensitivity low-energy collimator). Animal imaging demonstrated artifact-free imaging with superior resolution and image quality compared to conventional collimator images in several mouse and rat models. We conclude that: (a) CA imaging is a useful nuclear imaging technique for small animal imaging. The advantage in signal-to-noise can be traded to achieve higher resolution, decreased dose or reduced imaging time. (b) CA imaging works best for images where activity is concentrated in small volumes; a low count outline may be better demonstrated using conventional collimator imaging. Thus, CA imaging should be viewed as a technique to complement rather than replace traditional nuclear imaging methods. (c) CA hardware and software can be readily adapted to existing gamma cameras, making their implementation a relatively inexpensive retrofit to most systems.