Universitätsklinik Balgrist

Postoperative graft tear is correlated with poor clinical outcome after superior capsule reconstruction (SCR) for irreparable rotator cuff tears. The objective of this study was to investigate the optimal tension of the SuturePatch, which has been developed to reinforce SCR. Eight fresh-frozen cadaveric shoulders were tested by using a custom shoulder-testing system. Superior glenohumeral translation, subacromial peak contact pressure, and glenohumeral range of motion (ROM) were compared among 4 conditions: (1) intact; (2) irreparable supraspinatus and infraspinatus tears; (3) SCR using a thin fascia lata graft and SuturePatch augmentation performed at 20° glenohumeral abduction; and (4) SCR using the same graft with SuturePatch augmentation performed at 30° glenohumeral abduction. Increased superior glenohumeral translation and subacromial peak contact pressure after creation of an irreparable supraspinatus and infraspinatus tendon tear significantly decreased after SCR with SuturePatch augmentation performed at both 20° and 30° glenohumeral abduction. Superior glenohumeral translation and subacromial peak contact pressure did not differ between 20° and 30° glenohumeral abductions. Internal rotation (P = .39-.99), external rotation (P = .61-.99), or total rotational ROM (P = .51-.99) were comparable between the irreparable supraspinatus and infraspinatus tendon tear condition and SCR with SuturePatch augmentation at both 20° and 30° glenohumeral abduction. SCR with SuturePatch augmentation restored superior glenohumeral stability and maintained glenohumeral ROM. When the SuturePatch is used to augment the graft of SCR, 30° or 45° of shoulder abduction (equal to 20° or 30° of glenohumeral abduction) may provide the optimal tension for graft attachment to the glenoid medially and greater tuberosity laterally.

Anterior cruciate ligament (ACL) injuries are common in competitive alpine skiing and pose significant challenges for return-to-performance (RTP) pathways. The aim of this scoping review was to map the current state of research, identify key factors for recovery, highlight knowledge gaps and synthesize evidence- and expert-informed practice recommendations for RTP after ACL injury. A search was conducted in four electronic databases using a set of pre-defined search terms. Studies that examined relevant aspects of RTP in competitive alpine skiers (not competitive para alpine skiers or recreational alpine skiers) who had suffered an ACL injury were included. Two assessors independently screened titles, abstracts and full-text sources to determine eligibility. Of the 622 double-removed hits from the literature search and the two studies added manually, 35 studies were included in this scoping review based on the eligibility criteria. The entities extracted included study characteristics such as general descriptors, injury patterns, surgical details, rehabilitation/training activities, testing/monitoring metrics, and key outcomes. The extracted data were then narratively/descriptively synthesized across several key domains. Most studies identified focus on epidemiology, secondary risks and early rehabilitation, with limited research on later recovery phases, such as returning to competition and returning to performance. There is also little evidence regarding the psychological and social factors that influence RTP. While further research is needed to fill these knowledge gaps, we propose a sport-specific, criteria-based and multi-domain RTP framework with stepwise progression on snow. Finally, we provide insights into practical implementation and present a comprehensive and jointly created RTP protocol for competitive alpine skiers to serve as a guideline for evidence- and expert-informed practice.

Nonbiodegradable metal screws used for fixation in the Latarjet procedure can cause complications, including irritation from prominent hardware and the need for revision surgery. Magnesium-based, bioabsorbable screws may address these concerns. This study compared the biomechanical performance of magnesium screws to titanium screws with the hypothesis that there is no statistically significant difference between both groups. Fourteen fresh-frozen cadaveric shoulders were matched by age and sex. Seven shoulders underwent a standard Latarjet procedure using two 5 mm cannulated partially threaded magnesium screws (average age 70.6 ± 9.4 years). The other 7 were fixed with two 4.5 mm cannulated partially threaded titanium screws (average age 71.4 ± 14). All shoulders underwent biomechanical testing with direct pressure on the graft: cyclic loading (100 cycles 10 N- 100 N) was performed to assess displacement, stiffness and load-to-failure. Those were measured using force-displacement data obtained through a mechanical testing system. Maximum cyclic displacement was 1.2 ± 0.6 mm for magnesium and 1.4 ± 1.1 mm for titanium screws (P = .643). Cyclical stiffness was 329 ± 147 N/mm (magnesium) vs. 402 ± 220 N/mm (titanium, P = .489). Construct stiffness was 327 ± 141 N/mm vs. 408 ± 207 N/mm (P = .425), and ultimate load to failure was 414 ± 128 N vs. 475 ± 271 N (P = .605). Bone block failure with screw bending was the most common failure mode in both groups. No statistically significant differences in biomechanical performance were found between magnesium and titanium screws in this time-zero biomechanical study. Magnesium screws may offer a viable bioabsorbable alternative that reduces complications from permanent hardware.

Static posterior shoulder subluxation (SPSL) is associated with both glenoid retroversion and altered acromial morphology. Although abnormal glenoid anatomy has been considered a crucial etiological factor, the biomechanical role of acromial anatomy remains incompletely understood. Combined acromial and glenoid malalignment would produce greater posterior humeral head translation than either deformity alone, and targeted corrections could restore posterior stability. Controlled laboratory study. Six fresh-frozen cadaveric shoulders underwent testing in a 6 degrees of freedom, 8-muscle actuated ex vivo cadaveric simulator. Seven conditions were tested: (1) intact, (2) posterior labral detachment, (3) isolated glenoid malalignment (-15° retroversion), (4) isolated acromial malalignment (high/flat), (5) combined malalignment, (6) acromial malalignment + glenoid correction + posterior acromial bone graft (PABG), (7) combined malalignment + PABG. Humeral head translation was measured during forward flexion at 30°, 50°, and 70° of elevation and normalized to glenoid width. Statistical analysis used repeated-measures analysis of variance with Bonferroni correction. Posterior labral detachment showed minimal effect (1.3% ± 2.4% translation). On average, isolated glenoid malalignment increased posterior translation by 29%, whereas isolated acromial malalignment produced 31% posterior translation. Combined malalignment resulted in 54% posterior translation (P < .05 for all comparisons), demonstrating additive effects. Glenoid correction with PABG partially restored humeral head translation, but did not restore glenohumeral centering, with a residual 20% posterior translation compared with the intact shoulder. Adding a PABG to the combined malalignment led to a measurable reduction in posterior translation. However, although the graft decreased translation by approximately 13%, it did not restore native kinematics. Glenoid as well as acromial malalignment alone is associated with pathological posterior translation of the humeral head across the glenoid upon simulated active elevation. Combined acromial and glenoid malalignment produces significantly greater posterior translation than either deformity alone. Complete anatomic correction of both deformities is necessary to restore normal posterior shoulder kinematics, supporting a comprehensive surgical approach for SPSL treatment.

Diagnosing simple valgus instability of the elbow currently involves time- and cost-intensive imaging modalities such as magnetic resonance imaging or magnetic resonance arthrography. Previous studies have demonstrated that stress radiography represents an alternative diagnostic tool for such conditions. The aim of this study was to investigate whether standardized valgus stress radiography can identify soft-tissue lesions of the medial elbow. A telos stress device (telos GAIII/E; telos Arzt- und Krankenhausbedarf GmbH, Woelfersheim-Bernstadt, Germany) was used to apply 50 N of valgus stress to 6 cadaveric elbows during static radiographic imaging. Forearm flexor and extensor tendons were loaded with 25 N and 20 N, respectively. Ulnohumeral joint spaces (mm) were measured with the joint in the intact state (M1), after transection of the medial collateral ligament (M2) and after release of the common flexor tendon (M3). Imaging was repeated in 0°, 30°, and 60° flexion with the forearm in neutral rotation, supination, and pronation in each position. Mean joint gapping was increased in all groups representing ligament- and/or tendon-deficient joint conditions compared with the intact (stressed) state (group M1). The absolute difference in ulnohumeral joint gapping after common flexor tendon transection compared with the uninjured state was statistically significant (P < .05) in all positions but not in 30° flexion and supination. Medial joint laxity was greater in 60° than 0° or 30° flexion. Joint spaces were greater in pronation and neutral rotation compared with supination. Telos stress radiographic imaging can be used to detect large ligamentous injuries at the medial elbow. Dynamic joint stabilization might affect the detection of medial collateral ligament injuries. Stress radiographic imaging at the elbow should involve examination of the joint at flexion angles of 60°.

Body Integrity Dysphoria (BID) is a condition characterized by a mismatch between an individual's physical body and their desired body state, often involving a desire for amputation. Virtual reality (VR) offers a non-invasive way to explore the effects of virtual embodiment on body ownership and sensorimotor integration. This study investigated the behavioral, phenomenal, and neurophysiological effects of embodying an amputated virtual body in three groups. Twenty individuals with BID (BID), 20 individuals with involuntary lower leg amputation or congenital limb absence (AMP), and 20 non-clinical controls (NCC) were exposed to an immersive virtual scene of a virtual body (complete or amputated) from a first-person (1PP) or third-person perspective (3PP) with synchronized visuomotor and visuotactile stimulation. Mu suppression (8-13Hz) was assessed as marker for sensorimotor resonance using electroencephalography, alongside questionnaire-based assessments of body ownership and agency, as well as performance in a leg length estimation task. Individuals with BID reported significantly stronger ownership and agency over the amputated virtual body, particularly in the 1PP condition. Mu suppression in 1PP was (a) greater in BID than AMP, and (b) more pronounced when viewing an amputated body than a complete body across all groups. All participants estimated their leg as shorter after embodying the amputated avatar, reflecting a malleability in body schema following virtual embodiment. The findings demonstrate that virtual embodiment can significantly influence body experiences, the body schema, and neural activity. VR holds potential as a non-invasive tool for exploring body representation and could further provide therapeutic benefits for individuals with BID.

Spinal cord injury (SCI) incidence is rising among the elderly, yet the relationship between age and recovery remains controversial. The aim of this study was to evaluate the relationship between age and neurologic and functional outcomes and to identify an age cutoff associated with a decline in recovery. We conducted a prospective cohort study using data from patients with traumatic and ischemic SCI enrolled in the European Multicenter Study about Spinal Cord Injury between 2001 and 2022. Linear regression models assessed the relationship between age and changes from baseline to 1 year after SCI in the total motor score (TMS) of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) and in the Spinal Cord Independence Measure (SCIM) total score. Additional analyses examined the relationship between age and the evolution of ISNCSCI light-touch and pinprick scores, as well as ambulation parameters (6-minute walking test, 10-meter walking test, and Walking Index for Spinal Cord Injury). Models were adjusted for baseline scores, sex, year of injury, American Spinal Injury Association Impairment Scale (AIS) grade, and level of injury. The age cutoff was determined using a change-point model. A total of 2,171 patients (median age 47 years, 77.9% male, 51.9% injured at the cervical level, and 50.0% with a motor complete injury [AIS-A and AIS-B]) were included in the analysis. Increased age was not associated with changes in TMS (p = 0.896) but was significantly associated with reduced SCIM improvement (p < 0.001), with an estimated decline of 4.3 SCIM points per decade of age. Sensory outcomes were not significantly affected by age (Δlight-touch: p = 0.273; Δpinprick: p = 0.520) while ambulation recovery declined with increasing age (all outcomes p < 0.01). A noticeable reduction in functional recovery was observed in patients older than 70 years. Older age does not seem to affect neurologic recovery but is linked to poorer functional and ambulation outcomes. These findings, including the identified age cutoff, should inform future clinical trial design and guide tailored care strategies for older adults with SCI. ClinicalTrials.gov Identifier NCT01571531.

Tendons are sparsely vascularized connective tissues that link muscles to bones, withstanding some of the highest mechanical stresses in the body. Mechanical overloading and tissue hypervascularity are implicated in tendinopathy, a common musculoskeletal disorder, yet their mechanistic roles remain unclear. Here, we identify hypoxia-inducible factor 1α (HIF1α) as not only a marker but also a driver of tendinopathy. Histological and multiomics evaluation of human tendinopathic samples revealed extensive extracellular matrix remodeling, including pathological collagen cross-linking coinciding with active hypoxic signaling. Hypothesizing a causal contribution of hypoxia signaling, we generated mice with tenocyte-targeted deletions of the von Hippel-Lindau (Vhl) gene, which controls hypoxia signaling by regulating HIFα degradation. Vhl inactivation was sufficient to induce pathological hallmarks of tendinopathy, such as collagen matrix disorganization, cross-linking, altered mechanics, and neurovascular ingrowth. This phenotype was HIF1α dependent given that codeleting HIF1α rescued tendon morphology and mechanics. Moreover, deleting vascular endothelial growth factor A (Vegfa) alongside VHL effectively suppressed neovascularization but failed to rescue extracellular matrix abnormalities or restore mechanical function, emphasizing a direct role of HIF1α in driving tendon disease independently of angiogenesis. Mechanistically, we found that HIF1α activation was strain dependent in primary cultured human tendon cells and induced by mechanical overload in murine tendon explants. Furthermore, genetically removing Hif1α from tenocytes prevented aberrant tendon remodeling in response to chronic overload. These findings position HIF1α signaling as a central driver of tendinopathy that acts through a maladaptive tissue response to chronic overload, providing mechanistic insights that could be leveraged for therapeutic approaches.