Meghan Kelly

Biological Augmentation of Flexor Tendon Repair: A Challenging Cellular Landscape.

Advances in surgical technique and rehabilitation have transformed zone II flexor tendon injuries from an inoperable no-mans land to a standard surgical procedure. Despite these advances, many patients develop substantial range of motion-limiting adhesions after primary flexor tendon repair. These suboptimal outcomes may benefit from biologic augmentation or intervention during the flexor tendon healing process. However, there is no consensus biological approach to promote satisfactory flexor tendon healing; we propose that insufficient understanding of the complex cellular milieu in the healing tendon has hindered the development of successful therapies. This article reviews recent advances in our understanding of the cellular components of flexor tendon healing and adhesion formation, including resident tendon cells, synovial sheath, macrophages, and bone marrow-derived cells. In addition, it examines molecular approaches that have been used in translational animal models to improve flexor tendon healing and gliding function, with a specific focus on progress made using murine models of healing. This information highlights the importance of understanding and potentially exploiting the heterogeneity of the cellular environment during flexor tendon healing, to define rational therapeutic approaches to improve healing outcomes.

Techniques of Force and Pressure Measurement in the Small Joints of the Wrist

Background: The alteration of forces across joints can result in instability and subsequent disability. Previous methods of force measurements such as pressure-sensitive films, load cells, and pressure-sensing transducers have been utilized to estimate biomechanical forces across joints and more recent studies have utilized a nondestructive method that allows for assessment of joint forces under ligamentous restraints. Methods: A comprehensive review of the literature was performed to explore the numerous biomechanical methods utilized to estimate intra-articular forces. Results: Methods of biomechanical force measurements in joints are reviewed. Conclusions: Methods such as pressure-sensitive films, load cells, and pressure-sensing transducers require significant intra-articular disruption and thus may result in inaccurate measurements, especially in small joints such as those within the wrist and hand. Non-destructive methods of joint force measurements either utilizing distraction-based joint reaction force methods or finite element analysis may offer a more accurate assessment; however, given their recent inception, further studies are needed to improve and validate their use.

Dynamic Functional Assessment of Hand Motion Using an Animation Glove: The Effect of Stenosing Tenosynovitis.

Background: The aim of the present study is to determine whether an animation glove can be utilized to provide a reliable and reproducible assessment of dynamic hand function and whether this assessment is altered in the setting of hand pathology. Methods: Ten subjects without known hand pathology and 11 subjects with known stenosing tenosynovitis were assessed on tasks involving hand function at varied speeds, including forceful and gradual making of a fist and the quick and slow grip of a baseball using an animation glove to record range of motion and measures of velocity (CyberGlove II). Results: In normal subjects, peak extension and flexion velocity of the index and middle finger was highest in the metacarpophalangeal and lowest in the distal interphalangeal; however, the converse was true in the ring finger. In those subjects with stenosing tenosynovitis, the animation glove was able to detect a triggering event during assessment. Furthermore, there was a significant decrease in the maximum velocity of the proximal interphalangeal joint observed with the slow fist task in both flexion and extension (55%, P < .01) in the affected hand when compared with the unaffected hand. Conclusions: The CyberGlove II can be utilized in the dynamic functional analysis of the hand and is able to detect a triggering event in subjects with known stenosing tenosynovitis. Those subjects demonstrate a significant decrease in maximum velocity in slow fist tasks, highlighting the need for comprehensive assessment to ascertain the full extent of functional limitations that can occur in the setting of hand pathology.

Estrogen Deprivation and Diet-Induced Obesity Result in Alterations in Bone and Cartilage Content in the Murine Hip

Objectives: Arthroscopic treatment of femoroacetabular impingement (FAI) has been shown to result in significant improvement in pain and function. However, female gender and obesity have been linked to poor patient reported outcomes following surgery. Despite this, there remains a paucity of literature examining the effect of estrogen deprivation and obesity on the pathomorphology of the hip joint. Thus, the aim of this study was to examine the effect of estrogen deprivation and diet -induced obesity on articular cartilage and bone content in the femoral head in a murine model. Methods: Female C57Bl/6J mice underwent ovariectomy (OVX) or sham (SHA) procedure at 16 weeks of age. At 20 weeks of age mice were placed on either a high fat diet (HFD, 60% kcal fat) or low fat diet (LFD, 10% kcal fat) for 12 weeks. Mice placed on a high fat diet (both OVX and SHA) exhibited significant weight gain and increased plasma concentrations of fasting glucose and leptin. At the time of sacrifice, one hip was disarticulated and the femur was cleaned of soft tissue attachments. The femur was then placed in 10% formalin for microCT and histological assessment. The femurs were embedded in paraffin and underwent Safranin O/Fast green staining. Histomorphometric analysis was performed utilizing Osteomeasure analysis software and quantification of cortical and trabecular bone within the femoral head utilized Amira 3D software platform. Two-way ANOVA with a Bonferroni post-hoc analysis was used to detect significant differences due to diet or ovariectomy with differences considered significant at p<0.05. Results: Ovariectomy resulted in a small but significant loss (-14%) in cortical bone volume within the femoral head (p=0.0469) while high fat diet resulted in a similar loss (-15%) in femoral head cortical volume (p=0.007, interaction effect p=0.0913). In addition, ovariectomy resulted in a loss of trabecular bone volume within the femoral head (-10%, p=0.0178); however there was no effect of high fat diet on trabecular bone content (p=0.645). Histomorphometric assessment demonstrated that ovariectomy resulted in a 15% loss in total hip cartilage area (p=0.0117) and this was accompanied by a 15% loss in mineralized cartilage area (p=0.0101) without a loss in unmineralized cartilage (p=0.849). Similar effects were not observed in response to a high fat diet. Conclusion: This is the first study to demonstrate characteristic histomorphometric changes within the murine hip due to estrogen deprivation and obesity. Mice that have either undergone ovariectomy or have been placed on a high fat diet demonstrate a loss of cortical bone volume within the femoral head, however these effects do not appear to be additive. Furthermore, while estrogen deprivation induces a loss of trabecular bone, total cartilage and mineralized cartilage, a similar effect is not seen in response to a high fat diet. These findings suggest that the mechanisms by which estrogen deprivation and obesity elicit changes in bone and cartilage content may be different. Furthermore, these effects, specifically within the femoral head, may be a causative factor for poorer patient reported outcomes following hip arthoscopy in women and obese patients.

Novel Physical Therapy Protocol Results in Increased Compressive Strain and Improved Outcomes in Insertional Achilles Tendinopathy

Category: Ankle, Hindfoot, Sports Introduction/Purpose: Insertional Achilles Tendinopathy (IAT) affects 5% of the general population and up to 20% of the athletic population. Despite trials of non-surgical management, over 50% of patients ultimately pursue surgery. Previously in healthy controls it was demonstrated that ankle dorsiflexion tasks increase transverse compressive strain (force perpendicular to the tendon fibers) most in the deep region of the tendon insertion, where IAT is often most severe. Thus the purpose of this study was to utilize a novel physical therapy protocol that combines isometric and eccentric exercises in order to increase transverse compressive strain and decrease axial tensile strain (force parallel to tendon fibers) in patients with IAT and to determine whether this corresponds with improved patient outcome scores. Methods: Forty-two patients with IAT were enrolled in the study from May 2014 to June 2016, of which twenty-seven patients (mean age: 56.7 + 9.9 years, BMI: 29.6 + 5.9, 56% women) completed the study. A subset (n=15, mean age 58.9 + 8.6 years, BMI: 30.0 + 4.0, 47% women) underwent ultrasound elastography to determine transverse compressive and axial tensile strain in the Achilles tendon during dorsiflexion tasks. Patients were then placed on a physical therapy protocol that focused on progressive loading of the Achilles tendon while avoiding ankle dorsiflexion. Seated isometric plantar flexion, bilateral eccentric heel lowering, and single limb heel lowering exercises were utilized. Questionnaires validated for use in Achilles tendinopathy, the Victorian Institute of Sport Assessment – Achilles (VISA-A) and the Foot and Ankle Ability Measure (FAAM), were completed at the beginning and at the completion of the study. Results: Twenty-three of 27 subjects that completed the study, had clinically significant improvements in their VISA-A (mean change 19.3) or FAAM ADL and sports scores (mean change 16.2 and 22.6, respectively). Ultrasound elastography revealed that the deep region of the Achilles tendon experienced more transverse compressive strain and less axial tensile strain compared to the superficial portion of the tendon when standing. Completion of the physical therapy program resulted in increased transverse compressive strain in the superficial Achilles tendon compared to the pre-therapy value when standing (mean change 52%, p=0.043). Moreover, there was a decrease in axial tensile strain within the deep portion of the tendon in response to physical therapy (mean change 53% p=0.0434). Conclusion: Treatment of IAT patients with a physical therapy protocol utilizing a combination of isometric and eccentric exercises results in improved outcomes, as measured by VISA-A and FAAM questionnaires. Furthermore, ultrasound elastography suggests that while the physical therapy protocol increases the transverse compressive strain in the superficial portion of the Achilles tendon, it results in decreased axial tensile strain in the deep portion of the tendon. Therefore, it is likely that the combination of these two exercise modalities result in the improved clinical outcomes observed in our patients with IAT after undergoing this physical therapy protocol.

Spring Ligament Tear Decreases the Ankle and Talonavicular Joint Reaction Forces: Biomechanical Study of the Tibiocalcaneonavicular Ligament Reconstruction

Category: Other Introduction/Purpose: Spring ligament tear is often noted in advanced stages of the adult acquired flatfoot deformity (AAFD). Previous anatomic studies demonstrated that the spring and deltoid ligaments are not separate structure, but form a confluent ligament in which the tibiocalcaneonavicular ligament (TCNL) comprises the largest component. A biomechanical study which utilized stage IIB AAFD model demonstrated inferior result of the anatomic spring ligament reconstruction compared to the tibionavicular ligament reconstruction. Therefore, the TCNL reconstruction has been proposed for effective restoration of the ankle and talonavicular joints stability in AAFD with a large spring ligament tear. We aimed to investigate if spring ligament tear of greater than 1.5 cm decreases the ankle and talonavicular joint reaction forces (JRF), and if they could be restored by the TCNL reconstruction. Methods: Ten fresh-frozen human cadaveric lower legs were obtained and disarticulated at the knee joint. Steinmann pins were percutaneously placed across the distal tibia, center of the talus and navicular while preserving adjacent soft tissues. A distraction force was applied across the ankle and talonavicular joints to determine the baseline force displacement curve to generate a best- fit polynomial equation to determine normal JRF. A spring ligament injury model was created by releasing the medial capsuloligamentous complex of the talonavicular joint and extending the resection 1.5 cm proximally. The TCNL reconstruction was performed with a forked semitendinosus allograft. The folded portion of the graft was fixed to the medial malleolar inter- colliculus. One limb of the separated part of the allograft was fixed to the navicular tuberosity and the other limb was fixed to the calcaneus below the sustentaculum tali. The resultant JRFs across the tibiotalar and talonavicular joints were measured after each step. Results: The mean baseline JRFs of the ankle and talonavicular joints were 8.36 N +/- 1.8 N and 3.01 N +/- 0.9 N, respectively. The spring ligament tear resulted in 29% decrease in tibiotalar JRF (5.97 N +/- 1.1 N, p< 0.05) and 13% decrease in talonavicular JRF (2.63 N +/- 0.8 N, p>0.05). Although the tibionavicular ligament reconstruction partially restored JRFs of the tibiotalar (7.83 +/- 2.4 N, p> 0.05) and talonavicular joints (4.08 N +/- 1.8 N, p> 0.05), they were not statistically significant. Addition of the tibiocalcaneal ligament reconstruction resulted in significantly increased JRFs of the tibiotalar (9.17 +/- 3.93 N, p> 0.05) and talonavicular joints (4.35 +/- 2.04 N, p> 0.05) compared to the spring ligament injury model. Conclusion: This is the first biomechanical study to demonstrate that a large size (>1.5 cm) spring ligament tear results in decreased JRF of the ankle joint. The decreased ankle and talonavicular JRFs were effectively restored by the novel TCNL reconstruction. This technique utilizes a forked allograft with two limbs for the tibionavicular and tibiocalcaneal ligaments reconstructions. Advanced AAFD with a large size spring ligament tear may have medial ankle instability that should not be overlooked. The novel TCNL reconstruction should be considered to prevent progression of valgus deformity. The biomechanical and clinical efficacies of the TCNL reconstruction warrant further investigation.

A Novel Method for Measurement of Ankle Joint Reaction Force and Response to Syndesmotic Injury

Category: Ankle. Introduction/Purpose: Increasing evidence has suggested that alterations in joint mechanics results in articular pathology. Previous studies demonstrated noninvasive measurements of joint reactive forces (JRF) can be performed reliably without destruction of the peri-articular soft tissue in medium and small size joints of the upper extremity. This study presents a novel, noninvasive measurement of the JRF to investigate the normal and the effects of a syndesmotic injury. The JRF of the tibiotalar joint was also evaluated following anatomic reduction with fixation and malreduction of the syndesmosis. Methods: Eight fresh-frozen human cadaveric lower extremity limbs were obtained disarticulated above the knee. A distraction force was applied across the tibio-talar joint to determine the baseline (normal) ankle force displacement curve. Next, a syndesmotic injury was created by releasing the interosseous syndesmotic ligaments, the transverse tibiofibular ligament and the anterior and posterior tibiofibular ligaments. Prior to sectioning, two drill holes were placed across the joint and tapped to ensure anatomic reduction. JRF were measured using a quadricortical technique with a single or double screw configuration. The syndesmosis was malreduced by anteriorly displacing the fibula 5 mm. After each step, the resultant JRFs were determined using a distraction force across the tibiotalar joint. Results: Force displacement curves obtained from multiple measurements from each specimen with a mean ankle JRF of 31.4 + 2.6 N. Syndesmotic injury resulted in a 35% decrease in tibiotalar JRF (20.3 + 3.0 N, p=0.002). Fixation of the injury using one syndesmotic screw resulted in significant increase in JRF compared to injury JRF (28.7 + 1.4 N, p=0.02). Syndesmotic fixation with 2 screws also demonstrated a trend towards restoration of tibiotalar JRF (28.3 + 2.2 N, p=0.06). There was no statistical difference between fixation of one versus two syndesmotic screws. The JRF for the malreduced syndesmosis was 31.5 + 1.8 N (p=0.03,) resulting in increased forces approaching the baseline JRF. Conclusion: This study demonstrates a non-destructive model by which to measure joint reactive forces (JRF) across the tibiotalar joint and that these forces are diminished as a result of a syndesmotic injury, suggesting joint instability. Surgical stabilization with either 1 or 2 screws creates JRF that are similar to the normal JRF. Even with a malreduced syndesmosis, there appeared to be a JRF similar to baseline tibiotalar joint forces. However malreduction of the syndesmosis may alter the joint dynamics of the ankle in ways that were not measured in this study.