Musculoskeletal abnormalities in a large international cohort of boys with 49,XXXXY.

49,XXXXY is the rarest X and Y chromosomal variation, with an incidence of 1 in 80,000-100,000 live male births and has been associated with numerous musculoskeletal abnormalities. Data was collected from an international cohort of boys with 49,XXXXY over 10 years. Children were evaluated by a multidisciplinary team consisting of a pediatric orthopedist, a neurogeneticist, a neurodevelopmentalist, and two physical therapists. Increased rates of torticollis (32.4%), hamstring tightness (42%), radioulnar synostosis (67.6%), pes planus (65.2%), and other foot abnormalities (86.9%) were observed. Several anomalies increased with age, specifically hamstring tightness, kyphosis, and scoliosis. The elucidation of the orthopedic profile of this population is necessary in order to provide healthcare providers with current medical information. This research further supports the necessity for the comprehensive multidisciplinary treatment of boys with 49,XXXXY.

Assessment of Flexion Strength Following Single- Versus Double-Hamstring Tendon Harvest for Anterior Cruciate Ligament Reconstruction.

PURPOSE: To compare isometric hamstring strength deficits, knee laxity, functional outcomes, and patient-reported outcomes between patients who underwent anterior cruciate ligament (ACL) reconstruction with doubled semitendinosus and gracilis tendon autograft (ST/G) versus quadrupled semitendinosus autograft (ST), at a minimum follow-up of 1-year postoperatively. METHODS: Patients who underwent ACL reconstruction with ST/G or ST hamstring autografts were retrospectively identified. Isometric hamstring strength was tested with a hand-held dynamometer at 30, 60, and 90° of knee flexion. Anterior knee laxity was assessed using a KT-1000 arthrometer. Functional outcomes were collected using the single-leg hop test and single-leg squat test. Side-to-side differences were determined and compared between the ST/G and ST groups. Patient-reported outcomes were collected on all patients. RESULTS: Eighty-four patients who underwent ST/G (n = 34) or ST (n = 50) autograft ACL reconstruction were recruited to participate in this study. There was no difference in knee laxity between the groups. Side-to-side hamstring strength deficits increased with increased flexion angles. At 90° of flexion, the ST/G group had a significantly greater flexion strength deficit compared with the ST group (37.8 ± 15.1% vs 24.7 ± 12.5%, P < .001). Aside from a significant difference in the KOOS pain Score (P .045), no other significant differences in functional or patient reported outcomes between the groups were identified. CONCLUSIONS: Patients who underwent ACL reconstruction with ST/G compared with ST autograft have a significantly greater isometric flexion strength deficit at 90° of flexion. Future investigations are required to determine the clinical relevance of this difference and whether specialized therapy protocols can mitigate this deficit. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Quadriceps muscle compensatory activations are delayed following anterior cruciate ligament reconstruction using hamstring tendon graft.

BACKGROUND: Compensatory and anticipatory quadriceps activation (CQA and AQA) in response to postural perturbations are essential for functional stability of the knee. This study aimed at investigating CQA and AQA before and after anterior cruciate ligament reconstruction (ACLR) using hamstrings graft. METHODS: Twelve participants with ACLR and 12 healthy controls were exposed to 10 either unpredictable or predictable perturbations of the knee before ACLR (T1), two months (T2) and six months (T3) after surgery. Latencies of CQA and AQA in vastus lateralis (VL), rectus femoris (RF) and vastus medialis (VM) were measured. RESULTS: Latency of CQA was delayed in ACLR compared to controls at T1 for VL (105 ±â€¯25 vs. 57 ±â€¯9 ms; P < .001), RF (102 ±â€¯23 vs. 56 ±â€¯9 ms; P < .001) and VM (107 ±â€¯24 vs. 66 ±â€¯16 ms; P < .001), at T2 for VL (68 ±â€¯14 vs. 55 ±â€¯10 ms; P < .01) and at T3 for VL (105 ±â€¯22 vs. 58 ±â€¯7 ms; P < .001), RF (102 ±â€¯22 vs. 58 ±â€¯12 ms; P < .001) and VM (106 ±â€¯20 vs. 63 ±â€¯8 ms; P < .001). AQA occurred earlier in ACLR than in controls at T1 for VL (-82 ±â€¯64 vs. -14 ±â€¯11 ms; P < .05) and VM (-105 ±â€¯68 vs. -9 ±â€¯12 ms; P < .05). CONCLUSION: CQA are delayed following ACLR with hamstring graft and should be addressd by post-surgical rehabilitation.

Proximal hamstring tendon avulsion injuries occur predominately in middle-aged patients with distinct gender differences: epidemiologic analysis of 263 surgically treated cases.

PURPOSE: Epidemiologic data of proximal hamstring avulsions have mainly been reported in relatively small patient cohorts. Detailed information on patient demographics, injury mechanism, and injury patterns is lacking in the literature. Since these injuries are rare and frequently misdiagnosed, a better understanding may help to increase awareness and to improve diagnosis of proximal hamstring avulsions. METHODS: A chart review was performed to identify all patients who had undergone surgical repair for complete proximal hamstring avulsions between 01/2006 and 02/2019 at the authors' institution. The following demographic and injury-specific data were obtained: Sex, age, body mass index (BMI), cause of injury (sports, activities of daily living, and others), presence of neurologic symptoms referable to the sciatic nerve, time to surgery, injury pattern (affected tendons), tendon retraction, and type of injury according to Wood et al.`s classification (Type 1: osseous avulsions, Type 2: tear at the musculotendinous junction, Type 3: incomplete avulsion from bone, Type 4: complete avulsion with only minimal retraction, and Type 5: complete avulsion with retraction > 2 cm). Data were analyzed for the entire study population and group comparison was performed with regard to sex, cause of injury, and the type of injury. RESULTS: A total of 263 patients were included (53% male). The mean age was 49 ± 13 years with most patients (56%) aged between 45-59 years. Most injuries occurred while participating in sports (52%) and injury type 5 was most commonly diagnosed (66%). Five percent of patients had sensory deficits referable to the sciatic nerve. Gender comparison showed that female patients were significantly older, predominantly represented in the age group 45-59 years, and most commonly injured during activities of daily living, whereas male patients were significantly more often represented in younger age groups, and the most common cause of injury was sports. Compared to Type 4 and 5 injuries, patients with a Type 1 injury were significantly younger and had a significantly longer time to surgery. CONCLUSION: Proximal hamstring avulsion occurs predominately in the middle-aged patient and only rarely in patients under the age of 30 years. No gender dominance exists. Female patients are typically older and get injured during activities of daily living, whereas male patients are younger and get injured more often during sports. These epidemiologic data may help physicians to make an accurate and early diagnosis. LEVEL OF EVIDENCE: IV.

Abduction in Proximal Hamstring Tendon Avulsion Injury Mechanism: A Report on 3 Athletes.

Proximal hamstring tendon avulsions are typically sustained during forced hip hyperflexion combined with knee extension. We present 3 cases of athletes with a proximal hamstring tendon avulsion caused by an alternative injury mechanism that also involves a considerable hip abduction component (flexion-abduction injury mechanism). All cases had at least one concurrent injury of the medial thigh muscles, either on the ipsilateral or contralateral side. The 2 elite athletes with this injury mechanism returned to sport at preinjury level relatively quickly. A history of the flexion-abduction mechanism should raise suspicion of a hamstring tendon avulsion with concomitant injury of the medial thigh muscles. The magnetic resonance imaging (MRI) protocol should include both legs, and any concurrent injury may need to be addressed as well. In future studies, it would be interesting to investigate whether injury mechanism holds prognostic value in proximal hamstring tendon avulsions.

Functional outcomes following contralateral hamstring tendon autografts with extra-articular tenodesis for ACL revision surgery.

BACKGROUND: Lateral extra-articular procedure in association with ACL reconstruction can act as a protection against undesired load occurring during early postoperative phases, thus making it useful in revision ACL surgery. The purpose of the present study is to retrospectively review the clinical outcome of contralateral hamstring tendon autografts with extra-articular tenodesis for ACL revision surgery, specifically with regard to patient satisfaction, return to preinjury activity level, and postoperative functional outcomes. The hypothesis was that this combined procedure leads to improved stability and functional outcome in patients affected by ACL re-tear. METHODS: Twelve patients who underwent ACL revision surgery using contralateral hamstring tendon autografts and extra-articular tenodesis were retrospectively reviewed at an average follow-up of 4.1 years (range, 2 to 7 years). All the operations were performed by a single senior surgeon. The Tegner, Lysholm, International Knee Documentation Committee (IKDC) Subjective Knee Form were used. Objective evaluation included range of motion, Lachmann test, pivot-shift test and KT-1000 instrumented laxity testing. Wilcoxon test was utilized to compare the preoperative and follow-up status. Differences with a P value <0.05 were considered statistically significant. RESULTS: Lysholm knee score as well as IKDC score significantly improved at follow-up (P<0.05). No significant differences concerning Tegner activity level were reported (P=0.9). In terms of knee stability, anterior tibial translation according to manual laxity testing and as measured with KT-1000 arthrometer significantly improved after surgery (P<0.05). CONCLUSIONS: The present study shows favorable results for revision ACL reconstruction with contralateral hamstrings and associated extra-articular tenodesis concerning subjective knee function and knee stability as well as ability to resume sport activities.

Long-term muscle changes after hamstring lengthening in children with bilateral cerebral palsy.

AIM: To evaluate short-term (1y postoperatively; E1) and long-term (at least 4y postoperatively; E2) changes in hamstring muscle-tendon length (MTL) and lengthening velocity after hamstring lengthening in children with bilateral cerebral palsy (CP). METHOD: Three-dimensional gait analysis was performed in 19 children (16 males, 3 females; 36 limbs; mean age at surgery 9y [SD 3y]; range 6-10y) with flexed knee gait, preoperative ankle dorsiflexion lower than 20 degrees, and CP before bilateral hamstring lengthening (E0), at E1 and E2. Hamstring MTL (normalized by leg length) and velocity were assessed via OpenSim software. RESULTS: MTL increased from E0 to E1 (p=0.004) and decreased from E1 to E2 (p<0.020). Hamstring lengthening velocity did not change. In the subgroup with short, not slow hamstrings, the increase in MTL was maintained at E2. INTERPRETATION: Hamstring lengthening is an efficient procedure to lengthen short and/or slow hamstrings short-term. The desired outcome with maintenance of the postoperative changes in hamstring MTL is only achieved for preoperatively short, not slow hamstrings. WHAT THIS PAPER ADDS: Surgical hamstring lengthening can be confirmed via musculoskeletal modelling in OpenSim software. Surgical hamstring lengthening in cerebral palsy does not change hamstring lengthening velocity. Short, not slow hamstrings present a long-lasting muscle-tendon length (MTL) increase after hamstring lengthening. Changes in MTL after hamstring lengthening cannot be maintained for slow hamstrings. MTL does not change after hamstring lengthening for neither short nor slow hamstrings.

CAMBIOS MUSCULARES A LARGO PLAZO DESPUÉS DEL ALARGAMIENTO DE LOS ISQUIOTIBIALES EN NIÑOS CON PARÁLISIS CEREBRAL BILATERAL: OBJETIVO: Evaluar los cambios a corto plazo (un año después de la operación; E1) y a largo plazo (al menos cuatro años después de la operación; E2) de la longitud del tendón muscular de los isquiotibiales (LT) y la velocidad de alargamiento después del estiramiento en niños con parálisis cerebral bilateral (PC). MÉTODO: Se realizó un análisis tridimensional de la marcha en 19 niños (16 varones, tres mujeres; 36 extremidades; edad media en la cirugía 9 años [DS 3 años]; rango 6-10 años) con la marcha en flexión de la rodilla, dorsiflexión preoperatoria del tobillo inferior a 20 grados, antes del alargamiento bilateral de los isquiotibiales (E0), en E1 y E2. El LT de los músculos isquiotibiales (normalizado por la longitud de la pierna) y la velocidad fueron evaluadas mediante el OpenSim. RESULTADOS: El LT aumentó de E0 a E1 (p = 0,004) y disminuyó de E1 a E2 (p<0,020). La velocidad de alargamiento de los isquiotibiales no cambió. En el subgrupo con isquiotibiales cortos, pero no lentos, el aumento de la LT se mantuvo en E2. INTERPRETACIÓN: El alargamiento de los isquiotibiales es un procedimiento eficiente para los isquiotibiales cortos y/o lentos a corto plazo. El resultado deseado con el mantenimiento de los cambios postoperatorios en la longitud de los isquiotibiales solo se logra para los isquiotibiales cortos no lentos antes de la operación.

ALTERAÇÕES MUSCULARES A LONGO PRAZO APÓS ALONGAMENTO DE ISQUIOTIBIAIS EM CRIANÇAS COM PARALISIA CEREBRAL BILATERAL: OBJETIVO: Avaliar a curto (um ano de pós-operatório; E1) e longo prazo (no mínimo quatro anos de pós-operatório; E2) alterações no comprimento do tendão do músculo (CTM) isquiotibial e a velocidade de estiramento após alongamento do isquiotibial em crianças com paralisia cerebral bilateral (PC). MÉTODO: Foi realizada a análise tridimensional da marcha em 19 crianças (16 meninos, três meninas; 36 membros; média de idade de cirurgia de 9 anos [DP 3 anos]; variação de 6-10 anos) com marcha com flexão de joelho, ângulo de dorsiflexão de tornozelo menor que 20o no pré-operatório, e PC antes do alongamento bilateral dos isquiotibiais (E0), em E1 e E2. CTM dos isquiotibiais (normalizado pelo comprimento da perna) e a velocidade foram avaliados pelo OpenSim. RESULTADOS: CTM aumentou de E0 para E1 (p=0,004) e diminuiu de E1 para E2 (p<0,020). A velocidade de estiramento do isquiotibial não mudou. No subgrupo com isquiotibial encurtado e não lento, o aumento no CTM foi mantido em E2. INTERPRETAÇÃO: O alongamento do músculo isquiotibial é um procedimento eficiente para alongar isquitotibiais encurtados e/ou lentos a curto prazo. O resultado desejado com a manutenção das alterações no pós-operatório no CTM do isquiotibial é atingida somente para isquiotibial curto e não lento no pré-operatório.

A Single Bundle Anterior Cruciate Ligament Reconstruction (ACL-R) Using Hamstring Tendon Autograft and Tibialis Anterior Tendon Allograft: A Comparative Study.

The main purpose of this study was to compare the clinical outcomes of patients undergoing a single bundle anterior cruciate ligament reconstruction (ACL-R) of using quadrupled hamstring (4HT) autografts and two-strand tibialis anterior (2TA) allografts, and to find out the rate of graft failure and possible causes. We hypothesized that there would be no difference in the clinical outcome, and graft failure would be associated with the use of small sized allograft in young active males with high demand of sports activities. We retrospectively evaluated 222 patients (male, n=167, female, n=55) undergoing ACL-R between January 2010 and July 2014. Of 222 patients, 115 were included in the 4HT autograft group and 107 patients in the 2TA allograft group. Inclusion criteria were primary unilateral ACL-R with a minor MCL (

Snapping Biceps Femoris Tendon.

A 23-year-old male active duty soldier presented with a biceps femoris tendon snapping over the fibular head with flexion of the knee beyond 90°. Surgical release of anomalous anterolateral tibial and lateral fibular insertions provided relief of snapping with no other repair or reconstruction required. The soldier quickly returned to full running and active duty. Snapping biceps femoris tendon is a rare but potential cause of pain and dysfunction in the lateral knee. The possible anatomical variations and the cause of snapping must be considered when determining the operative approaches to this condition.

Proximal hamstring tendinopathy: pathophysiology, diagnosis and treatment.

Proximal hamstring tendinopathy is a chronic degenerative disease associated with progressive morbidity and functional decline. There is a growing incidence of the disease process but diagnosis is commonly delayed as patients present with vague and indolent symptoms, often without a specific precipitating injury. Treatment is also challenging as the existing literature varies in the nomenclature used for proximal hamstring tendinopathy and clinical trials use different management protocols with variable follow-up times. This review explores the existing literature on proximal hamstring tendinopathy and discusses the relevant anatomy, pathology, medical history, differential diagnosis, clinical assessment, diagnostic imaging and treatment of patients with proximal hamstring tendinopathy. This structured approach to proximal hamstring tendinopathy will enable clinicians to better understand the pathophysiology of the disease process, improve referrals to diagnostic imaging, and follow a stepwise approach to medical treatment and surgical referral.

Mid-term development of hamstring tendon length and velocity after distal femoral extension osteotomy in children with bilateral cerebral palsy: a retrospective cohort study.

AIM: Flexed knee gait can be treated with distal femoral extension osteotomy (DFEO) and additional patellar tendon advancement (PTA) in children with cerebral palsy (CP). This study assesses changes in hamstring muscle tendon length (MTL) and velocity after DFEO (+PTA). METHOD: Nineteen children (mean age 13y [standard deviation 3y] at surgery) with CP and flexed knee gait who were treated with DFEO (15 limbs) or DFEO+PTA (10 limbs) were retrospectively included in this study. Gait analyses were performed preoperatively (E0), 1 year postoperatively (E1), and for 10 limbs additionally 2 to 5 years postoperatively (E2). Hamstring MTL and velocities were assessed at all examination dates using OpenSim. RESULTS: Hamstring MTL and velocity did not change significantly over time. From E0 to E1, knee flexion in stance improved for both DFEO and DFEO+PTA (p<0.05), knee flexion in swing only improved after DFEO+PTA (p<0.05). The improved knee flexion in stance and swing was maintained at E2. INTERPRETATION: DFEO led to a significant improvement in knee kinematics at E1 which was maintained at E2. DFEO seems to prevent recurrent hamstring tightness but does not lead to lengthened or fastened hamstrings. WHAT THIS PAPER ADDS: Distal femoral extension osteotomy (DFEO) does not change hamstring muscle tendon length. DFEO does not change hamstring lengthening velocity. DFEO leads to a significant improvement in knee kinematics. Changes in knee kinematics after DFEO can be maintained at mid-term. DFEO seems to prevent recurrent hamstring tightness.

[Basic Clinical Examination of the Shoulder]. / Klinische Basisuntersuchung der Schulter.

OBJECTIVE: Successful treatment of shoulder disease requires an accurate diagnosis. In addition to differentiated history taking, clinical examination is the most important component in the diagnosis of shoulder diseases. METHOD: The present video explains the common provocation tests and functional tests that are used in the basic clinical examination of the shoulder. In addition to general inspection and palpation, the focus is on different diagnostic tests and clinical signs that improve diagnostic accuracy. CONCLUSION: The present basic clinical examination methods allow a structured approach to clinical issues and can be a good basis, if supplemented by further specific and individual tests.

Unilateral Snapping Biceps Femoris Tendon with an Anomalous Insertion Treated with Anatomic Repositioning and Lengthening with a Single Suture Anchor: A Report of Two Cases.

CASE: A snapping biceps femoris tendon, a rare etiology for symptomatic pain in the lateral aspect of the knee, has been reported infrequently. We report 2 cases of an acutely symptomatic unilateral snapping biceps femoris tendon with an intraoperatively intact anomalous insertion onto the tibia, which were treated with anatomic repositioning and "pie-crust" lengthening via a single suture anchor. CONCLUSION: Anatomic repositioning and lengthening is a novel technique that successfully resolved the painful snapping and allowed full return to competitive sports by 6 months postoperatively, with maintenance of improvement at ≥14 months postoperatively.

The effect of targeted exercise on knee-muscle function in patients with persistent hamstring deficiency following ACL reconstruction - study protocol for a randomized controlled trial.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction, using hamstring auto-graft is a common surgical procedure, which often leads to persistent hamstring muscle-strength deficiency and reduced function. The purpose of this randomized controlled trial (RCT) is to investigate the effect of a combined, progressive, strength and neuromuscular exercise intervention on knee muscle strength, functional capacity and hamstring muscle-tendon morphology in ACL-reconstructed patients with persistent hamstring muscle-strength deficiency compared with controls. METHODS/DESIGN: The study is designed as a multicenter, parallel-group RCT with balanced randomization (1:1) and blinded outcome assessments (level of evidence: II) and will be reported in accordance with the CONSORT Statement. Fifty ACL-reconstructed patients (hamstring auto-graft) with persistent limb-to-limb knee-flexor muscle-strength asymmetry at 12-24 months' post surgery, will be recruited through outpatient clinics and advertisements. Patients will be randomized to a 12-week progressive, strength and neuromuscular exercise group (SNG) with supervised training twice weekly or a control intervention (CON) consisting of a home-based, low-intensity exercise program. Outcome measures include between-group change in maximal isometric knee-flexor strength (primary outcome) and knee-extensor muscle strength, hamstring-to-quadriceps strength ratios of the leg that has been operated on and Knee injury and Osteoarthritis Outcome Score (KOOS) (secondary outcomes). In addition, several explorative outcomes will be investigated: The International Knee Documentation Committee Subjective Knee Form (IKDC), the Tegner Activity Score, rate of force development (RFD) for the knee flexors and extensors, tendon regeneration and potential muscle hypertrophy at graft harvest site evaluated by magnetic resonance imaging (MRI), postural control, kinetic/kinematic gait characteristics and knee-related functional capacity. DISCUSSION: This RCT is designed to investigate the effect of combined, progressive-resistance and neuromuscular exercises on knee-flexor/extensor strength, in the late rehabilitation phase following ACL reconstruction. Reduced hamstring strength represents a potential risk factor for secondary ACL rupture and accelerated progression of osteoarthritis. If deemed effective, the intervention paradigm introduced in this study may help to improve current treatment strategies in ACL-reconstructed patients. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT02939677 (recruiting). Registered on 20 October 2016.

A meta-analysis comparing tenotomy and tenodesis for treating rotator cuff tears combined with long head of the biceps tendon lesions.

PURPOSE: The purpose of this meta-analysis was to assess whether there were differences in the outcomes between tenotomy and tenodesis in treating LHBT lesions combined with rotator cuff repairs. METHODS: Using Medline, Embase, and Cochrane, we searched for articles comparing tenotomy and tenodesis combined with rotator cuff repair which were published before April 2016 with the terms "biceps", "tenotomy", "tenodesis", and "rotator cuff". The controlled clinical studies that met the inclusion and exclusion criteria were assessed for quality of methodology by utilizing the Coleman score. RESULTS: On the basis of the inclusion and exclusion criteria, ten articles (903 patients) were included in this meta-analysis. The Coleman score ranged between 40 and 89 in the included studies. The results showed that the incidence of the popeye sign (OR, 2.777, P = 0.000) were higher in tenotomy group compared with tenodesis group when concomitant rotator cuff repair. Statistically significant difference in favor of tenodesis was observed for Constant score (SMD, -0.230, P = 0.025). As for the arm cramping pain, patient satisfaction, VAS score, ASES score and UCLA increased score, the strength and the range of motion, there were no significant differences between tenodesis and tenotomy of the LHBT, corresponding to the currently available results in the literature. CONCLUSIONS: Based on this meta-analysis, both tenotomy and tenodesis are effective in pain relief and function improvement in patients with repairable rotator cuff tears. No significant differences in post-operative functional outcome between tenotomy and tenodesis for the treatment of LHBT lesions were observed except for a lower Constant score and higher risk of Popeye deformity in tenotomy.

Ropivacaine alters the mechanical properties of hamstring tendons: In vitro controlled mechanical testing of tendons from living donors.

OBJECTIVE: Intraarticular or periarticular injection of ropivacaine (RI) is an element of current knee surgery practices. The goal of this study was to determine the effects of RI on the mechanical properties of hamstring tendons. We hypothesized that RI would have a detrimental effect on the mechanical properties of periarticular soft tissues METHODS: A tensile test to failure was performed on 120 hamstring tendon segments harvested during ACL reconstruction surgery in 120 patients. Two sets of tensile tests were done. The first evaluated the effect of RI itself on the mechanical properties of tendons: 30 samples were soaked for 1hour in a 2% RI solution and compared to 30 samples soaked in a saline solution (control group). The second evaluated the effect of RI concentration on the mechanical properties of hamstring tendons: 30 samples were soaked for 1hour in a 2% RI solution and 30 samples were soaked in a 7.5% RI solution. RESULTS: In the first test, 29 samples from each group were analyzed as two samples (one in each group) failed at the grip interface. The specimens exposed to 2% RI had lower ultimate tensile strength (Δ=4.4MPa, P=0.001), strain energy (Δ=13MPa, P=0.001) and Young's modulus (Δ=1.6MPa, P=0.02) than the specimens in the control group. There was no significant difference in the strain at failure between groups (Δ=5%, P=0.3). In the second test, one specimen from the 7.5% RI group failed during the preloading and was excluded. There was no significant difference in terms of the load at failure and ultimate tensile stress (Δ=0.45MPa, P=0.6) and strain energy (Δ=0.49MPa, P=0.49) between the two groups. There were significant differences in terms of elongation at failure (Δ=28%, P=0.0003) and Young's modulus (Δ=2.6MPa, P=0.005), with the specimens exposed to 7.5% RI undergoing greater deformation and having a lower Young's modulus. DISCUSSION: While local RI injections are widely performed in clinical practice, the results of this in vitro study point to short-term alterations of the mechanical properties of hamstring tendons. If these results hold in vivo, this could lead to weakness of the soft tissues exposed to this product, particularly the tendons and ligaments around the injection area. LEVEL OF EVIDENCE: Experimental study. Level 1.

A new femoral fixation device for anterior cruciate ligament reconstruction using the outside-in technique and hamstring tendon graft: A comparison between two devices in cadaveric human knee models.

BACKGROUND: A new device (T-anchor) was developed for ACL reconstruction and is implanted via the outside-in technique using hamstring grafts. The purpose of this study was to compare the T-anchor with the EndoButton Direct. METHODS: This study was conducted on 30 cadaveric knees (15 matched pairs). There were two groups of 15 each in the T-anchor and EndoButton Direct groups. After the harvest of grafts, fixation site profile and graft length were measured by loading the grafts onto both devices. They were then tested on a universal testing machine to assess elongation after cyclic loading, load to failure, ultimate load, and mode of failure. RESULTS: The fixation site profile was lower in the T-anchor group than in the EndoButton Direct group (2.3±0.4mm vs. 4.7±1.0mm, P<0.001). The length of the graft-device complex of the T-anchor specimens was longer than that of the EndoButton Direct specimens (125.0±8.9mm vs. 115.0±8.7mm, P<0.001). The mean cyclic elongation was lower for the T-anchor group when compared with the EndoButton Direct group (2.4±0.6mm vs. 3.9±2.6mm, P=0.015). There was no statistically significant difference in ultimate load and load to failure between the T-anchor and EndoButton Direct groups. For mode of failure, the T-anchor fared better (P=0.013) with all failures attributed to specimens. CONCLUSIONS: In this cadaveric study, the new device, T-anchor, performed better than the EndoButton Direct with respect to the above-mentioned study parameters except for ultimate load and load to failure.