Diagnosis of ulnar nerve entrapment anterior to the medial epicondyle by ultrasound elastography and diffusion tensor imaging with fiber tractography: a case report

Ulnar/cubital tunnel syndrome is the second most common compressive neuropathy of the upper limb. Permanent location of the ulnar nerve anterior to the medial epicondyle is extremely rare, with only five cases reported in the literature. Using ultrasound elastography and diffusion tensor imaging with fiber tractography, we diagnosed a case in which ulnar nerve entrapment was associated with anterior nerve location. Surgical release confirmed the diagnosis and the patient was symptom free 3 months after surgery.

Nerve and Arterial Supply Pattern of the Popliteus Muscle and Clinical Implications

Introduction. The aim of this study was to investigate the nerve and artery supply and the tibial attachment of the popliteus muscle using anatomical methods. Methods. Forty-four nonembalmed and embalmed extremities were dissected for this study. To measure the attachment area of the popliteus, the most prominent points of the medial epicondyle of the femur and the medial malleolus of the tibia were identified before dissection. A line connecting these two prominent points was used as the reference line, with the most prominent point of the medial epicondyle of the femur as the starting point. This study also investigated the area where the popliteus attaches to the bone and the points where nerves and arteries enter the popliteus muscle when it is divided into three equal parts in the coronal plane. Results. The mean length of the reference line was 34.6 ± 2.1 cm . The origin of the popliteus was found to be at a distance of 16.6% to 35.2% on the tibial bone from the proximal region. The popliteus was innervated by only the tibial nerve in 90% of the cases and by the tibial and the sciatic nerves in the remaining 10% of the cases. The inferior medial genicular artery and the posterior tibial artery supplied blood to the popliteus in 90% and 65% of the cases, respectively. When the popliteus muscle was divided into three equal parts in the coronal plane, the nerve and the artery were found to enter the muscle belly in zones II and III and zones I and II in 92% and 98% of the specimens, respectively. Discussion. The anatomical investigation of the popliteus in this study will help identify patients with clinically relevant syndromes.

Role of dynamic ultrasound in assessment of the snapping elbow and distal biceps tendon injury

Introduction Ultrasound is useful in assessing patients with snapping syndromes around the elbow joint. The dynamic nature of the examination allows for direct visualisation of the underlying causative factor. Topic description: We discuss the role of dynamic ultrasound in assessing various snapping syndromes around the elbow, such as ulnar nerve instability, snapping triceps and less commonly, snapping brachialis. Ultrasound is also useful in evaluating the distal biceps tendon, particularly in differentiating partial from complete tendon injury. Discussion Ulnar nerve instability and snapping triceps can be assessed via a medial approach with the transducer placed transversely between the medial epicondyle and the olecranon. In ulnar nerve instability, the nerve can be seen crossing over the medial epicondyle on elbow flexion. In snapping triceps syndrome, both the ulnar nerve and the distal triceps can be seen dislocating over the medial epicondyle. Dynamic assessment of the distal biceps tendon using a lateral approach minimises anisotropy artefact often seen on the anterior approach. Passive pronation and supination of the forearm will reveal little or no movement in a completely torn tendon whereas moving tendon fibres will be appreciated in partial tears. In a snapping brachialis, the medial portion of brachialis will be seen abnormally translocating anterolateral to the medial border of the trochlea during elbow flexion and snapping back into its normal position on elbow extension. Conclusion Dynamic ultrasound of the elbow is valuable in diagnosing patients with snapping sensations around the joint and in evaluating the integrity of the distal biceps tendon.

Medial Epicondyle Apophyseal Avulsion Fractures in Youth Throwers: A Severe Variant of Little League Elbow (132)

Objectives: Medial epicondyle apophyseal avulsion fractures sustained during throwing represent an understudied, severe variant of medial epicondyle apophysitis, or ‘Little League elbow’. The current study sought to characterize presenting features, treatment options, and clinical results of a large cohort of pre-adolescent and adolescent patients who presented with these fractures. Methods: Skeletally immature athletes with medial epicondyle apophyseal avulsion fractures sustained during throwing from 2003-2017 at a tertiary-care pediatric referral center were identified. Exclusion criteria were fractures sustained during non-throwing activity or prior elbow fracture. Medical records and radiographic images were reviewed for study variables. Treatment decisions were made independently by fellowship-trained pediatric orthopaedic surgeons or sports medicine physicians on a case-by-case basis. Patients treated with open reduction and internal fixation (ORIF) were compared to those treated non-operatively, and all fracture patients were compared to a larger control group of patients diagnosed with medial epicondyle apophysitis/Little League elbow with no fracture. Results: During the study period, a total of 317 patients were diagnosed with Little League elbow due to medial epicondyle apophyseal overuse injury, 50 of whom (16%) sustained a discreet, radiographically confirmed epicondyle fracture sustained during a single throw. Median age of the fracture cohort at presentation was 13.1 years (range 8 years – 16 years). Forty-nine fracture patients (98%) were male baseball pitchers and one (2%) was a male football quarterback. Fracture patients had significantly higher median BMI (21.3 kg/m2 vs. 19.2kg/m2, p=0.004) than the apophysitis control group, but there was no significant difference in age. Of the 37 patients with documentation regarding pre-injury symptoms, 31 patients (84%) described pre-existing medical elbow pain prior to their acute injury, while 6 (16%) denied pain prior to the inciting throw. Of the 12 patients (24%) with documented shoulder exams at presentation, 5 (42%) demonstrated glenohumeral internal rotation deficit (GIRD). Twenty-three patients (46%) were treated with ORIF (22 single screw fixation; 1 suture anchor fixation), while 27 (54%) were treated non-operatively. Median fracture displacement was significantly greater in operative patients than non-operative patients (5.0mm vs. 3.0mm, p=<.001), with all ‘minimally displaced’ (<4mm) fractures undergoing non-operative treatment (Figure 1). Multivariable analysis determined that for each additional mm of displacement, the odds of surgical intervention increased by 6.4 times (OR=6.36; 95% CI=1.83-22.07; p=.004), when controlling for age and BMI. All patients returned to their throwing sport (RTS) at a median of 12.8 weeks post-diagnosis, but 13 (26%) developed recurrent elbow pain, with no significant difference in in RTS time or recurrence rate between treatment cohorts. Nine of twenty-two (41%) screw ORIF patients underwent secondary implant removal, with no significant difference in this rate between those with or without a washer. Conclusions: Medial epicondyle apophyseal avulsion fractures in youth throwers represent a severe variant of Little League elbow, constituting approximately 16% of cases within the condition’s spectrum. These fractures may be effectively treated with either non-operative measures, particularly minimally displaced fractures <4mm, or ORIF, though >40% of operative patients may require implant removal. A large majority of patients reported medial elbow pain prior to fracture, suggesting this severe presentation of Little League elbow may be preventable.

A Cadaveric Study of Ulnar Nerve Movement and Strain around the Elbow Joint

There is a lack of data on how ulnar nerve strain varies according to the location around the elbow joint. Therefore, we measured the longitudinal movement of the ulnar nerve around the elbow joint. Four fresh-frozen cadaveric upper extremities were used. A linear displacement sensor was attached to the ulnar nerve at eight measurement points at 20-mm intervals. At each point, the longitudinal movement of the ulnar nerve was measured during elbow flexion. We calculated the strain on the ulnar nerve based on the change in movement between neighboring points. Ulnar nerve movement with elbow flexion had a maximum value (mean, 10.5 mm; p < 0.001) at 2 cm proximal to the medial epicondyle. In the site distal to the medial epicondyle, the movement was small and demonstrated no significant difference between points (p = 0.1). The change in strain between mild flexion (0–60°) and deep flexion (60–120°) significantly differed at 2–4 cm and 6–8 cm proximal to the medial epicondyle (15% versus 3%, p < 0.01; 5% versus 9%, p < 0.05, respectively). The longitudinal movement of the ulnar nerve during elbow flexion occurred mainly at the site proximal to the medial epicondyle and became smaller away from the medial epicondyle.