Aims. The conventionally described mechanism of distal biceps tendon rupture (DBTR) is of a ‘considerable extension force suddenly applied to a resisting, actively flexed forearm’. This has been commonly paraphrased as an ‘eccentric contracture to a flexed elbow’. Both definitions have been frequently used in the literature with little objective analysis or citation. The aim of the present study was to use video footage of real time distal biceps ruptures to revisit and objectively define the mechanism of injury. Methods. An online search identified 61 videos reporting a DBTR. Videos were independently reviewed by three surgeons to assess forearm rotation, elbow flexion, shoulder position, and type of muscle contraction being exerted at the time of rupture. Prospective data on mechanism of injury and arm position was also collected concurrently for 22 consecutive patients diagnosed with an acute DBTR in order to corroborate the video analysis. Results. Four videos were excluded, leaving 57 for final analysis. Mechanisms of injury included deadlift, bicep curls, calisthenics, arm wrestling, heavy lifting, and boxing. In all, 98% of ruptures occurred with the arm in supination and 89% occurred at 0° to 10° of elbow flexion. Regarding muscle activity, 88% occurred during isometric contraction, 7% during eccentric contraction, and 5% during concentric contraction. Interobserver correlation scores were calculated as 0.66 to 0.89 using the free-marginal Fleiss Kappa tool. The prospectively collected patient data was consistent with the video analysis, with 82% of injuries occurring in supination and 95% in relative elbow extension. Conclusion. Contrary to the classically described injury mechanism, in this study the usual arm position during DBTR was forearm supination and elbow extension, and the muscle contraction was typically isometric. This was demonstrated for both video analysis and ‘real’ patients across a range of activities leading to rupture. Cite this article: Bone Jt Open 2022;3(10):826–831

The objectives of this study were to elucidate the function of Brachioradialis during forearm rotation to determine whether it is a neutralizing muscle and a protector of hyper-rotation by eccentric contraction. The distance from the brachioradialis (BRAR) origin to insertion was measured on 10 left fresh frozen cadaveric arms using an electromagnetic tracking system. This was done in 10¢. a. increments over the full range of forearm rotation. In addition, fine-wire electrodes were placed in the BRAR of twelve living subjects. EMG data was collected as the subject rotated the forearm in both a pronating and a supinating direction. The muscle length data shows that length is shortest at neutral and greatest closer to full rotation in either direction. When rotating from full pronation to neutral the EMG data show a steady increase while the muscle length decreases indicating a concentric contraction. When rotating from neutral to full pronation the muscle length increased and with load the EMG level increased indicating an eccentric contraction. During rotation from full supination to neutral, the EMG activity increased slightly with the muscle length, indicating a concentric contraction. When rotating from neutral to full supination, the EMG level remained variable while the muscle length increased indicating an eccentric contraction or a passive stretch. EMG activity can occur during isometric, eccentric, or concentric contractions, the accompanying muscle length data is useful for establishing the direction of the activity. We conclude BRAR is a neutralizing muscle as it has a linear relationship with EMG activity when returning the forearm to neutral. It also acts eccentrically slowing extreme pronation and thus it has a dynamic effect on DRUJ stability. This knowledge will assist surgeons in Tendon Transfer surgery and injury to the Brachioradialis muscle

Pectoralis major tendon rupture is a relatively rare injury, resulting from violent, eccentric contraction of the muscle. Over fifty percent of these injuries occur in athletes classically in weight-lifters during bench press. In this study, thirteen cases of distal rupture of the pectoralis major muscle in athletes are presented. All patients underwent surgical repair. Physical findings and surgical technique are described. Magnetic resonance imaging was used in the diagnosis of all patients and intra-operative findings correlated with the reported scans in eleven patients with minor differences in two patients. During follow up examination, six patients had excellent results, six had good results and one had a fair result. Eleven patients could return to sports activity at their preoperative level. Among our patients we emphasize that of an orthopaedic resident who suffered a rupture of his pectoralis major tendon as an unusual complication of closed manipulation of an anterior shoulder dislocation. According to the literature and our experience, we suggest that only surgical repair of the pectoralis major rupture will result in complete recovery and restoration of the full strength of the muscle which is essential for the active athlete

Introduction and Aims: Pectoralis major tendon rupture is a relatively rare injury, resulting from violent, eccentric contraction of the muscle. Over 50percent of these injuries occur in athletes, classically in weight-lifters during bench press. Method: In this study, 13 cases of rupture of the pectoralis major muscle in athletes are presented. All patients underwent surgical repair. Physical findings and surgical technique are described. Magnetic resonance imaging was used in the diagnosis of all patients. Intra-operative findings correlated with the reported scans in 11 patients with minor differences in two patients. Results: During follow-up examination, six patients had excellent results, six had good results and one had a fair result. Eleven patients could return to sports activity at their pre-operative level. Among our patients we emphasise that of an orthopaedic resident who suffered a rupture of his pectoralis major tendon as an unusual complication of closed manipulation of an anterior shoulder dislocation. Conclusion: According to the literature and our experience, we suggest that only surgical repair of the pectoralis major rupture will result in complete recovery and restoration of the full strength of the muscle, which is essential for the active athlete

The early diagnosis of the suprascapular nerve (SSN) entrapment in overhead athletes with simultaneous shoulder injuries and its arthroscopic release plays an important role for their appropriate treatment and recovery. SSN release at suprascapular and spinoglenoid notches, seems very helpful for increasing their performance. 21 Elite overhead athletes were treated from Jan 2005–May 2009. From 16 to 34 years old, mean 26 years, 4 Javelin throwers (Olympic and National level thrower), 4 Weightlifters (International level), 8 Volleyball Players, 3 Kick Boxer, 2 Water Polo Players. Extreme ROM of arm creates large torques about the shoulder cycle of repetitive microtrauma to the SSN, Direct trauma: fracture, dislocation, blunt trauma traction injury, Sling effect with hyper-abduction injury at the SS Notch, Correlation ROM with SSN entrapment in volley ball players, Eccentric contraction of the ISP (spinoglenoid notch), Internal impingement, Rotator cuff tears, Biceps lesions, Instability, SLAP lesion, Bankart lesion, Mainly infraspinatus muscle atrophy. X-rays, Nerve conduction studies, EMG studies, MRI. All of them had complete pain relief, especially at the posterior shoulder, regained full ROM of the operated shoulder, 19 fully recovered at the pre-injury level, 2 at the postoperative phase, Muscle atrophy improved. Advanced SSN entrapment provoke significant muscle wasting, often irreversible. This underscores the importance of a quick and accurate diagnosis to appropriate intervention. The overhead athletes with increased ROM of their shoulder predispose in SSN entrapment and shoulder injuries and vice-versa. An arthroscopic shoulder procedure for repairing the glenohumeral pathology with a simultaneous arthroscopic SSN release seems to be the appropriate treatment regarding to our resu

We have developed a novel knee simulator that reproduces the active knee motion to evaluate kinematics and joint reaction forces of TKA. There have been developed many kinds of knee simulators; Most of them are to predict TKA component wear and the others are to evaluate the kinematics and/or kinetics of TKA. The most simulators have been operated using the data of the loading and kinematics profile of the knee obtained from normal gait. Here a problem is that such variables as joint force and kinematics are the outcome caused by the application of muscles' and external forces. If so, a simulator should be operated by the muscles' and external forces so as to duplicate the in vivo condition. Other disadvantages for the current knee simulators are; a knee joint motion is made passively, the effects of the hip joint motion are not taken into account, and the maximum flexion angle is usually limited at about 100°. Considering the above, we have developed a knee simulator with the following advantages and innovative features. First, the simulator is driven by the muscles' forces and an active knee motion is made with bearing the upper body weight. As a result, the knee shows a 3D kinematics and generates the tibio-femoral contact forces. Under this condition, the TKA performance is to be assessed. Secondly, a hip joint mechanism is also incorporated into the simulator. The lower limb motion is achieved by the synergistic function between the hip and knee joints. Under this condition, a natural knee motion is to be reproduced. Thirdly, the simulator can make complete deep knee flexion up to 180°. Thus not only the conventional TKA but also a new TKA for high flexion can be attached to it for the evaluation. Figure 1 shows the structure of the simulator, in which both the hip and knee joints are moved in a synergistic fashion by the pull forces of four wires. The four wires are pulled by the four servomotors respectively and reproduce the functions of the mono-articular muscles ((1), (3)) and the bi-articular muscles ((2), (4)) through the multiple pulley system. It should be noted that weight A and B are not heavy enough for the inverted double pendulum to stand up straight. They are applied as counter weights so that each segment duplicate the each segmental weight of the human lower limb. Figure 2 shows a sequential representation of stand to sit features: (a) at standing, (b) at high flexion, and (c) at deep flexion. At a state of 130° knee flexion between (b) and (c), hamstrings wire (4) becomes shortest and then exhibits an eccentric contraction, thereby attaining deep flexion. Our knee simulator can be a useful tool for the evaluation of TKA performance and may potentially substitute the in vivo experiments

Aims

This cross-sectional study aimed to investigate the in vivo ankle kinetic alterations in patients with concomitant chronic ankle instability (CAI) and osteochondral lesion of the talus (OLT), which may offer opportunities for clinician intervention in treatment and rehabilitation.

The purpose of this study was to investigate the mechanism of injury causing anterior cruciate ligament ruptures in snowboarders and skateboarders. Knee injuries in snowboarding and skateboarding are rare. We have seen 22 ACL ruptures with an identical injury mechanism that has not been previously described. Fifteen ACL ruptures occurred in snow-boarders and 7 in skateboarders. All were advanced or expert boarders. All injuries occurred on landing a high jump, which resulted in significant knee compression. All described a flat landing on a flexed knee with no twisting component. We postulate that anterior cruciate ligament rupture in these patients is due to explosive eccentric quadriceps contraction when landing from a jump. The injury mechanism is not boot induced as has been described in downhill skiers landing from a jump

Tendinopathy is a debilitating musculoskeletal condition which can cause significant pain and lead to complete rupture of the tendon, which often requires surgical repair. Due in part to the large spectrum of tendon pathologies, these disorders continue to be a clinical challenge. Animal models are often used in this field of research as they offer an attractive framework to examine the cascade of processes that occur throughout both tendon pathology and repair. This review discusses the structural, mechanical, and biological changes that occur throughout tendon pathology in animal models, as well as strategies for the improvement of tendon healing.

Cite this article: Bone Joint Res 2014;3:193–202.