Relative contributions of the supraspinatus cord and strap tendons to shoulder abduction and translation.

BACKGROUND: The supraspinatus (SS) is formed by a larger anterior bipennate muscle with a cord-like tendon and a posterior unipennate muscle with a strap-like tendon. There is a tendinous connection between the 2 SS subunits. Yet, the relative mechanical contribution of the SS cord and SS strap musculotendinous units to load transmission and subsequent shoulder abduction force is unknown. We hypothesized that a simulated SS cord vs. an SS strap tear would generate less shoulder abduction force and, further, an intact SS cord would offset the expected abduction loss from an SS strap tear, but the inverse would not be true. MATERIALS AND METHODS: Twenty fresh-frozen cadaveric specimens were tested in a shoulder simulator with physiological load vectors applied to the upper and lower subscapularis, SS cord, SS strap, infraspinatus, and teres minor. The roles of the SS cord and SS strap muscles were delineated by varying their loads, while keeping constant loads on other muscles. The randomized testing trials included a native condition and 4 test cases that simulated tears by dropping the load and force transfer via the SS cord-to-SS strap connection by adding the load. Testing was completed at both 0° and 30° of abduction. During each test, shoulder abduction force, rotator cuff strains, and humeral translation were measured. RESULTS: Simulated isolated SS cord and SS strap tears led to a significantly lower shoulder abduction force (P < .001). A simulated cord tear at 0° and 30° reduced the abduction force by 53% and 38%, respectively. A simulated strap tear at 0° and 30° dropped the abduction force by 27% and 23%, respectively. The decline in the abduction force was larger for the SS cord tear vs. SS strap tear (P ≤ .001). An SS cord tear with full-load transfer to the strap was able to recover to native values at both 0° and 30° (P ≥ .288). Likewise, an SS strap tear with full-load transfer to the SS cord showed a similar recovery to native values at both 0° and 30° (P ≥ .155). During full-load transfer, the tendon strain followed the loading pattern. An SS cord tear or SS strap tear did not cause a change in humeral translation (P ≥ .303). DISCUSSION: The mechanical findings support the efficacy of nonoperative treatment of small (<10 mm) SS tears,11 because an intact SS strap tendon can effectively offset the abduction loss of a torn SS cord tear and vice versa.

Locating the rotator cable during subacromial arthroscopy: bursal- and articular-sided anatomy.

BACKGROUND: The rotator cable (RCa) is an important articular-sided structure of the cuff capsular complex that helps prevent suture pull out during rotator cuff repairs (RCRs) and plays a role in force transmission. Yet, the RCa cannot be located during bursal-sided RCRs. The purpose of this study is to develop a method to locate the RCa in the subacromial space and compare its bursal- and articular-sided dimensions. METHODS: In 20 fresh-frozen cadaveric specimens, the RCa was found from the articular side, outlined with stitches, and then evaluated from the bursal side using an easily identifiable reference point, the intersection of a line bisecting the supraspinatus (SS) tendon and posterior SS myotendinous junction (MTJ). Four bursal-sided lengths were measured on the SS-bisecting line as well as the RCa's outside anteroposterior base. For the articular-sided measurements, the rotator cuff capsular complex was detached from bone and optically scanned creating 3D solid models. Using the 3D models, 4 articular-sided lengths were made, including the RCa's inside and outside anteroposterior base. RESULTS: The RCa's medial arch was located 9.9 ± 5.6 mm from the reference point in 10 intact specimens and 4.1 ± 2.4 mm in 10 torn specimens (P = .007). The RCa's width was 10.9 ± 2.1 mm, and the distance from the lateral edge of the RCa to the lateral SS insertion was 13.9 ± 4.8 mm. The bursal- and articular-sided outside anteroposterior base measured 48.1 ± 6.4 mm and 49.6 ± 6.5 mm, respectively (P = .268). The average inside anteroposterior base measurement was 37.3 ± 5.9 mm. DISCUSSION: The medial arch of the RCa can be reliably located during subacromial arthroscopy using the reference point, analogous to the posterior SS MTJ. The RCa is located 10 mm in intact and 4 mm in torn tendons (P = .007) from the posterior SS MTJ. If the above 6-mm shift in location of the RCa is not taken into consideration during rotator cuff suture placement, it could negatively affect time zero repair strength. The inside anteroposterior base of the RCa measures on average 37 mm; therefore, rotator cuff tears measuring >37 mm are at risk of rupturing part or all of the RCa's 2 humeral attachments, which if not recognized and addressed could impact postoperative function.

Management of irreparable massive rotator cuff tears: a systematic review and meta-analysis of patient-reported outcomes, reoperation rates, and treatment response.

BACKGROUND: There is no consensus on the treatment of irreparable massive rotator cuff tears. The goal of this systematic review and meta-analysis was to (1) compare patient-reported outcome scores, (2) define failure and reoperation rates, and (3) quantify the magnitude of patient response across treatment strategies. METHODS: The MEDLINE, Embase, CENTRAL (Cochrane Central Register of Controlled Trials), and Scopus databases were searched for studies including physical therapy and operative treatment of massive rotator cuff tears. The criteria of the Methodological Index for Non-randomized Studies were used to assess study quality. Primary outcome measures were patient-reported outcome scores as well as failure, complication, and reoperation rates. To quantify patient response to treatment, we compared changes in the Constant-Murley score and American Shoulder and Elbow Surgeons (ASES) score with previously reported minimal clinically important difference (MCID) thresholds. RESULTS: No level I or II studies that met the inclusion and exclusion criteria were found. Physical therapy was associated with a 30% failure rate among the included patients, and another 30% went on to undergo surgery. Partial repair was associated with a 45% retear rate and 10% reoperation rate. Only graft interposition was associated with a weighted average change that exceeded the MCID for both the Constant-Murley score and ASES score. Latissimus tendon transfer techniques using humeral bone tunnel fixation were associated with a 77% failure rate. Superior capsular reconstruction with fascia lata autograft was associated with a weighted average change that exceeded the MCID for the ASES score. Reverse arthroplasty was associated with a 10% prosthesis failure rate and 8% reoperation rate. CONCLUSION: There is a lack of high-quality comparative studies to guide treatment recommendations. Compared with surgery, physical therapy is associated with less improvement in perceived functional outcomes and a higher clinical failure rate.

Clinical and functional impairment after nonoperative treatment of distal biceps ruptures.

BACKGROUND: Clinical and functional impairment after nonoperative treatment of distal biceps ruptures is not well understood. The goal of this study was to measure patients' perceived disability, kinematic adjustment, and forearm supination power after nonoperative treatment of distal biceps ruptures. METHODS: Fourteen individuals after nonoperative treatment of distal biceps ruptures were matched to a control group of 18 uninjured volunteers. Both groups prospectively completed the Disabilities of the Arm, Shoulder and Hand (DASH), Single Assessment Numerical Evaluation (SANE), and Biceps Disability Questionnaire. Both performed a new timed isotonic supination test that was designed to simulate activities of daily life. The isotonic torque dynamometer measures the supination arc, center of supination arc, torque, angular velocity, and power. Motion analysis quantifies forearm and shoulder contributions to the arc of supination. RESULTS: The nonoperative treated group's DASH (23.2 ± 10.3) and SANE (59.6 ± 16.2) scores demonstrated a clinical meaningful impairment. The control group showed no significant differences in kinematic values between dominant and nondominant arms (P = .854). The nonoperative biceps ruptured arms, compared with their uninjured arms, changed supination motion by decreasing the supination arc (P ≤ .036), shifting the center of supination arc to a more pronated position (P ≤ .030), and increasing the shoulder contribution to rotation (P ≤ .001); despite this adaptation, their average corrected power of supination decreased by 47% (P = .001). CONCLUSION: Patients should understand that nonoperative treatment for distal biceps ruptures will result in varying degrees of functional loss as measured by the DASH, SANE, and Biceps Disability Questionnaire, change their supination kinematics during repetitive tasks, and that they will lose 47% of their supination power.

Distal biceps tendon history, updates, and controversies: from the closed American Shoulder and Elbow Surgeons meeting-2015.

Understanding of the distal biceps anatomy, mechanics, and biology during the last 75 years has greatly improved the physician's ability to advise and to treat patients with ruptured distal tendons. The goal of this paper is to review the past and current advances on complete distal biceps ruptures as well as controversies and future directions that were discussed and debated during the closed American Shoulder and Elbow Surgeons meeting in 2015.

Management of rotator cuff tears.

Every year approximately 18 million Americans report shoulder pain, a large percentage of which are a result of rotator cuff disease. Rotator cuff tear progression can be difficult to predict. Factors associated with tear enlargement include increasing symptoms, advanced age, involvement of 2 or more tendons, and rotator cable lesion. Nonsurgical treatment can be effective for patients with full-thickness tears. When conservative treatment fails, surgical repair provides a reliable treatment alternative. Recurrent tears after surgery can compromise outcomes, particularly for younger patients with physically demanding occupations. Revision surgery provides satisfactory results for those with symptomatic re-tears. If the tear is deemed irreparable, addressing concomitant biceps pathology or performing partial repairs can reliably improve pain and potentially reverse pseudoparalysis. The reverse shoulder arthroplasty has limited indications in the setting of rotator cuff tears and should be reserved for patients with painful pseudoparalysis and associated arthropathy.

Management of full-thickness rotator cuff tears: appropriate use criteria.

BACKGROUND: The appropriate use criteria (AUC) were developed for full-thickness rotator cuff tears to determine when it is reasonable to recommend nonoperative care, partial repair/débridement, repair, reconstruction, or arthroplasty. The goal of this report was to interpret and summarize the results of the AUC process into clinically relevant terms. METHODS: Using the results of the AUC methodology, we systematically interpreted the clinical importance attributed to the various patient and pathologic variables. We then assessed the combination of considerations that would justify the various treatment options using "preference tables." RESULTS: A nonoperative program was appropriate if the patient had a positive response to conservative care. However, a repair could be maybe appropriate was also accepted. Rotator cuff repair was appropriate when conservative treatment failed in symptomatic patients. Reconstructive measures were recognized primarily in those with chronic massive tears. Most found arthroplasty maybe appropriate only in healthy patients, pseudoparalysis, and chronic massive tears. Surprisingly, neither factors that decreased healing nor adversely affected outcome had a strong influence on the panel's treatment recommendations. CONCLUSIONS: The AUC process accounts for clinical experience and considers individual patient and pathologic characteristics of the condition. Overall, the outcome of this exercise does support the current practice for the management of rotator cuff tears (ie, repair of symptomatic tears). However, the minimal importance given to patient and pathologic considerations, well documented to influence outcome, prompts an ongoing effort to refine this important and clinically relevant process.

Factors affecting supination strength after a distal biceps rupture.

HYPOTHESIS: This study quantified pain (visual analog pain scale [VAPS]), disability (Disabilities of the Arm, Shoulder and Hand [DASH]) and isometric supination torque at 3 forearm positions in a prospective cohort of biceps-deficient arms to assess the potential for functional return with nonoperative treatment. MATERIALS AND METHODS: Twenty-three men (50 ± 11 years) with complete unilateral distal biceps avulsion underwent isometric supination strength testing of both limbs at 60° of supination, 0° (neutral), and 60° of pronation. After exclusion of 1 outlier patient, the mean time from injury to evaluation was 44 days (range, 4-455 days). Pain level (VAPS) and functional outcome (DASH) were assessed; supination strength was normalized to the uninjured arm. RESULTS: The uninjured arm was stronger (P < .001), and peak torque varied with forearm position (P < .043). Peak torque was greater in pronation compared with supination, regardless of injury (P < .002). No differences were detected in supination strength as a result of forearm position or arm dominance. Supination strength did not correlate with time from injury to evaluation. One patient regained supination strength (115%) at 60° of pronation and 72% in neutral with a lengthy time from injury. VAPS (5 of 10) and DASH (39 of 100) scores decreased with time and did not relate to supination strength. CONCLUSION: Biceps tendon rupture led to a 60% decrease in supination strength in the neutrally oriented forearm. Peak torque observations can be explained using forearm moment arms. VAPS and DASH scores decreased with time but did not affect strength. We speculate that supination strength from pronation to neutral can improve as one strengthens the brachioradialis but strength deficits from neutral to supination are more difficult to overcome.

Effect of lesser tuberosity osteotomy size and repair construct during total shoulder arthroplasty.

BACKGROUND: Lesser tuberosity osteotomy has been shown to decrease postoperative subscapularis dysfunction. The purpose of this study was to determine the effect of osteotomy thickness and suture configuration on repair integrity. MATERIALS AND METHODS: One side of 12 matched-pair cadaveric shoulders was randomly assigned to either a thick osteotomy (100% of lesser tuberosity height) or a thin osteotomy (50% of height). Both sides of the matched pairs were given the same repair, either (1) compression sutures or (2) compression sutures plus 1 tension suture. This created 4 groups of 6 paired specimens. Computed tomography imaging was used to measure tuberosity dimensions before and after osteotomy to validate fragment height and area. The repairs were loaded cyclically and then loaded to failure. A video system measured fragment displacement. The percent area of osteotomy contact was calculated from the computed tomography and displacement data. RESULTS: The average initial displacement was less in the thin osteotomy groups (P = .011). Adding a tension suture negated this difference. A significant number of thin repair sites compared with thick repair sites remained intact during load-to-failure testing (P = .001). No difference occurred because of maximum load between the repair groups (P = .401), and construct stiffness was greater when a tension suture was used (P = .032). The percent area of osteotomy contact showed no differences between the osteotomy (P = .431) and repair (P = .251) groups. CONCLUSION: The study showed that thin osteotomies displaced less than thick osteotomies. Adding a tension band improved construct stability and eliminated some failure modes. Our ideal repair was a thin wafer with both tension and compression sutures. This construct had smaller total displacement, a high osteotomy percent contact area, and a high maximum load.

The distal biceps tendon.

Distal biceps tendon ruptures continue to be an important injury seen and treated by upper extremity surgeons. Since the mid-1980s, the emphasis has been placed on techniques that limit complications or improve initial tendon-to-bone fixation strength. Recently, basic science research has expanded the knowledge base regarding the biceps tendon structure, footprint anatomy, and biomechanics. Clinical data have further delineated the results of conservative and surgical management of both partial and complete tears in acute or chronic states. The current literature on the distal biceps tendon is described in detail.

The pathoanatomy of atraumatic partial distal biceps tears: a cadaveric study.

Background: Partial distal biceps tears can occur in the short and/or long heads, leading to forearm pain and weakness. Yet, the pathoanatomy of atraumatic and traumatic partial tears are not understood. The goals of this study are to determine the distal biceps partial tear frequency and tear pattern in a cohort of cadaveric specimens. Methods: Fifty three fresh frozen cadavers (average age 70.4 ± 13.8 years, range 32-94) underwent elbow endoscopy to screen for partial tears. The partial tendon tear pattern was classified into either attritional (atraumatic), detachment on the tendon's lateral side, or avulsion (traumatic) rupture of the tendon fibers from bone on both the lateral and medial sides. The specimens were dissected and laser scanned to make 3D models. The tear location, shape, and area were calculated using gross dissection and the 3D models. Results: Atraumatic partial distal biceps tears were identified in 40% of the specimens, 72% involved both the long and short heads, 14% long head, and 14% short head. In all tears, the tendon fibers were only detached from the lateral side. The greatest tear width occurred near the short and long head junction. Conclusion: Atraumatic partial distal biceps tears are common. The tear originates on the lateral side of the tendon at the short and long head junction. All the tear patterns are attritional and no specimen had surgical treatment. This finding supports the current treatment recommendation of an initial period of nonoperative care for symptomatic atraumatic partial distal biceps tears.

Repaired distal biceps magnetic resonance imaging anatomy compared with outcome.

BACKGROUND: This study examined the magnetic resonance imaging (MRI) appearance of an anterior incision distal biceps tendon repair and evaluated the association between appearance and outcome. MATERIALS AND METHODS: Nineteen patients were randomly recruited to undergo an elbow MRI from a single-surgeon series of distal biceps repairs using an anterior approach. Tendon healing was evaluated by the integrity of the repair, the amount of heterogeneity within the tendon substance, and the presence of heterotopic bone. The angle of tendon insertion on the tuberosity was used to quantify the tendon location from the MRI in the patients and in 10 healthy volunteers. All patients completed the Disabilities of Arm, Shoulder and Hand (DASH) and a visual analog pain scale (VAPS), and 17 patients underwent isometric supination strength testing. MRI findings were statistically compared with the outcome scores. RESULTS: All of the repairs healed to cortical bone. High intrasubstance heterogeneity or heterotopic bone was present in 11 patients (58%). The insertion site angle of the repaired tendons was 73° more anterior than the uninjured controls (P < .001). Average DASH was 7.7 (range, 0-49.2) and VAPS was 0.7 (range, 0-5). At 60° of forearm supination, supination strength was 67% of the uninjured side (P < .01). No significant differences in DASH or VAPS scores were found between groups based on tendon appearance. CONCLUSIONS: The distal biceps tendon predictably heals to cortical bone but demonstrates a wide variability in overall morphology that does not influence DASH or VAPS scores. A significant decrease in strength at 60° of supination appears to be an effect of an anterior tendon reattachment location.

Anatomic and biomechanical analysis of the short and long head components of the distal biceps tendon.

HYPOTHESIS: The short head bundle of the distal biceps tendon is more efficient at elbow flexion, and the long head is more efficient at forearm supination. METHODS: The short and long head bundles of the distal biceps tendon were separated to the bicipital tuberosity in 6 cadavers. The area and centroid of each bundle insertion were computed from surface points measured within each footprint. Each bundle was individually loaded. The supination torque and flexion load generated were recorded at 90° of elbow flexion. The slope of the torque generated versus biceps load was used to define the supination moment arm. The ratio of the flexion load generated to biceps load applied was used to define the relative flexion efficiency. RESULTS: The short head insertion was positioned distal and anterior relative to the long head and typically included the apex of the tuberosity. The areas of the long and short heads were 59 ± 15 and 94 ± 44 mm(2) (P = .07), respectively. The long head moment arm was significantly higher in supination. The short head had a significantly higher moment arm in neutral and pronation. The ratio of the flexion load to biceps load was 15% higher for the short head. CONCLUSION: The short and long heads of the biceps have distinct insertions. The short head's insertion allows it to be relatively more efficient at elbow flexion at 90°. In the neutral and pronated forearm, the short head is the relatively more efficient supinator. In the supinated forearm, the long head becomes relatively more efficient at supination.

Return to Play After Distal Biceps Tendon Repair.

PURPOSE OF REVIEW: Distal biceps tendon ruptures (DBTR) are uncommon injuries in 40- to 50-year-old men but occur at a younger age in the athlete population. The distal biceps tendon is an important supinator of the forearm and flexor of the elbow. A complete injury results in limiting function in the upper extremity. The current review evaluates the different options in management and the current literature on return to play in athletes. RECENT FINDINGS: The distal biceps tendon inserts on the posterior aspect of the radial tuberosity as two independent heads. The long head footprint is more proximal and posterior giving it a better lever arm for supination. The short head footprint is more distal and anterior giving it a better lever arm for flexion. Surgical anatomic repair is highly recommended among the athlete population, to restore proper function of the upper extremity. There is scarce literature on return to play among athletes. The most recent studies on high-performance athletes are on National Football League (NFL) players. These studies showed that 84-94% of NFL players returned to play at least one game after distal biceps repair. Compared to matched control groups, there was no difference in the player's performance after surgery. Anatomic repair of DBTR results in excellent outcomes, high return to work, and high rate of return to play among athletes. When compared to matched control groups, NFL players have the performance score and play the same number of games after surgery.

The Rotator Cable Does Not Stress Shield the Crescent Area During Shoulder Abduction.

BACKGROUND: It is accepted by the orthopaedic community that the rotator cable (RCa) acts as a suspension bridge that stress shields the crescent area (CA). The goal of this study was to determine if the RCa does stress shield the CA during shoulder abduction. METHODS: The principal strain magnitude and direction in the RCa and CA and shoulder abduction force were measured in 20 cadaveric specimens. Ten specimens underwent a release of the anterior cable insertion followed by a posterior release. In the other 10, a release of the posterior cable insertion was followed by an anterior release. Testing was performed for the native, single-release, and full-release conditions. The thicknesses of the RCa and CA were measured. RESULTS: Neither the principal strain magnitude nor the strain direction in either the RCa or the CA changed with single or full RCa release (p ≥ 0.493). There were no changes in abduction force after single or full RCa release (p ≥ 0.180). The RCa and CA thicknesses did not differ from one another at any location (p ≥ 0.195). CONCLUSIONS: The RCa does not act as a suspension bridge and does not stress shield the CA. The CA primarily transfers shoulder abduction force to the greater tuberosity. CLINICAL RELEVANCE: The CA is important in force transmission during shoulder abduction, and efforts should be made to restore its continuity with a repair or reconstruction.

Arthroscopic treatment of rotator cuff disease.

The goal of this article is to summarize the current concepts on rotator cuff disease with an emphasis on arthroscopic treatment. Most rotator cuff tears are the result of an ongoing attritional process. Once present, a tear is likely to gradually increase in size. Partial-thickness and subscapularis tears can both be successfully treated arthroscopically if conservative management fails. Partial tears involving greater than 50% of tendon thickness should be repaired. Articular-sided partial tears involving less than 50% of the rotator cuff can reliably be treated with debridement. A more aggressive approach should be considered for low-grade tears (<50%) if they occur on the bursal side. Biomechanical and anatomic studies have shown clear superiority with dual-row fixation compared with single-row techniques. However, current studies have yet to show clear clinical advantage with dual-row over single-row repairs. Biceps tenotomy or tenodesis can reliably provide symptomatic improvement in patients with irreparable massive tears. True pseudoparalysis of the shoulder is a contraindication to this procedure alone and other alternatives should be considered.

Partial Distal Biceps Avulsion Results in a Significant Loss of Supination Force.

BACKGROUND: Partial avulsions of the short and/or long head of the distal biceps tendon cause pain and loss of strength. The goal of the present study was to quantify the loss of supination and flexion strength following a series of surgical releases designed to simulate partial and complete short and long head traumatic avulsions. METHODS: Mechanical testing was performed to measure supination moment arms and flexion force efficiency on 18 adult fresh-frozen specimens in pronation, neutral, and supination. The distal biceps footprint length was divided into 4 equal segments. In 9 specimens (the distal-first group), the tendon was partially cut starting distally by releasing 25%, 50%, and 75% of the insertion site. In the other 9 specimens (the proximal-first group), the releases started proximally. Mechanical testing was performed before and after each release. RESULTS: Significant decreases in the supination moment arm occurred after a 75% release in the distal-first release group; the decrease was 24% in pronation (p = 0.003) and 10% in neutral (p = 0.043). No significant differences in the supination moment arm (p ≥ 0.079) or in flexion force efficiency (p ≥ 0.058) occurred in the proximal-first group. CONCLUSIONS: A simulated complete short head avulsion significantly decreased the supination moment arm and therefore supination strength. CLINICAL RELEVANCE: A mechanical case can be made for repair of partial distal biceps tendon avulsions when the rupture involves ≥75% of the distal insertion site.

Proper insertion angle is essential to prevent intra-articular protrusion of a knotless suture anchor in shoulder rotator cuff repair.

The advent of new arthroscopic devices has led to the development of novel techniques of arthroscopic rotator cuff repair. However, failure to recognize specific technical aspects and improper application of these devices can lead to complications. We report a case of intra-articular protrusion of knotless anchors (PEEK PushLock SP, 4.5 x 18.5 mm; Arthrex, Naples, FL), used in the lateral row of a suture-bridging technique for arthroscopic rotator cuff repair. This case draws attention to the increased length of such devices when compared with traditional suture anchors, the technical aspects of proper device use, the possible patient-related factors such as implant-patient size mismatch, and the importance of additional imaging for the investigation of failure to progress postoperatively.

The effect of biceps reattachment site.

BACKGROUND: We hypothesize that an anatomic repair of the distal biceps tendon would recreate native tendon moment arm and forearm rotation, while a nonanatomic insertion would compromise moment arm and forearm rotation. METHODS: Isometric supination torque was measured at 60° of pronation, neutral, and 60° of supination for the native distal biceps tendon and 4 repair points in 6 cadaveric specimens using a computer controlled elbow simulator. The slope of the regression line fitted to the torque versus biceps load data was used to define the moment arm for each attachment location. Range of motion testing was performed by incrementally loading the biceps, while measuring the supination motion generated using a digital goniometer. RESULTS: Tendon location and forearm position significantly affected the moment arm of the biceps (P < .05). Anatomic repair in all forearm positions showed no significant difference from the native insertion. Moment arm for an anterior center repair was significantly lower in supination (-97%) and neutral (-27%) and also produced significantly less supination motion. No difference was observed between all tendon locations in pronation. CONCLUSIONS: Reattachment of the biceps to its anatomic location, as opposed to a more anterior central position, is critical in reestablishing native tendon biomechanics. Clinically, these findings would suggest that patients with a biceps repair might experience the most weakness in a supinated position without experiencing a deficit in the pronated forearm.