Citations

ABSTRACT Introduction Acute Compartment Syndrome (ACS) is a severe trauma caused by elevated intra-muscle-compartment pressure (ICP). The current standard method for diagnosis is to insert a needle into the muscle sterilely under anesthesia. However, to secure the environment is sometimes not easy and leads to delays in diagnosis. Recently, we have focused on shear wave ultrasound elastography (SWE) as an alternative, which can be done concisely in unclean environment and without anesthesia. We would like to report the usefulness of SWE for ACS diagnosis using 2-pedal walking turkey model recently developed in our lab. Materials and Methods A total of 32 1-year-old Bourbon turkeys were used. 5% solution of chicken albumin was infused continuously into the tibialis cranialis (TC) muscle using IV pump. The ICP was increased stepwise from 0 to 50 mmHg. During the rising of ICP, the correlation between values of SWE (kPa) and ICP (mmHg) was measured. After the ICP reached 50 mmHg, half of the turkeys were maintained at this pressure for 2 hours and the rest for 6 hours. After infusion, a fasciotomy was performed on the half turkey. Half of the turkeys were euthanized after 2 weeks and the rest after 6 weeks. SWE of TC muscle and walking gait data on turkeys using a portable walkway system were measured weekly until euthanasia. At euthanasia, isometric tetanic muscle force (ITF) tests to TC muscle and histological evaluations were performed. Results SWE value (kPa) was highly significantly correlated to the actual ICP (mmHg) (R2 = 0.91). Stance of ACS side leg were significantly extended, and swing of the control side shortened from the second to the third week after ACS in the 6 hours infusion-no-fasciotomy group (P < 0.05*). ITF was significantly reduced mainly in the 6 hours infusion group (P < 0.05*). Histological evaluation revealed that in the 6 hours infusion and 6 weeks survival group, both the muscle fiber and intercellular distances were significantly expanded (P < 0.05). Conclusion SWE seems to be a substitute measure of ICP in diagnosing ACS. With regard to our in vivo ACS model using turkey, survival at 50 mmHg ICP for 6 hours and 6 weeks post ACS would be an appropriate situation.

AbstractThis study aimed to compare the clinically established autologous extrasynovial tendon graft to a newly developed tissue‐engineered allograft (Eng‐allograft) in terms of functional outcomes following flexor tendon reconstruction in a canine model. The second and fifth flexor digitorum profundus (FDP) tendons from 16 dogs were transected and repaired in Zone II. After 6 weeks of cage activity, the repaired tendons were intentionally ruptured, creating a clinically relevant model for reconstruction. The re‐ruptured FDP tendons were then reconstructed using either the clinically standard autologous extrasynovial tendon graft or the Eng‐allograft, which had been revitalized with autologous bone marrow‐derived mesenchymal stem cells (BMSCs) and synovialized using carbodiimide derivatized synovial fluid (cd‐SYN). Following 12 weeks of postoperative rehabilitation, the functional outcomes of the surgical digits were evaluated. The Eng‐allograft group exhibited improved digital function, including lower digit work of flexion and reduced adhesion status, while maintaining similar tendon gliding resistance compared to the autograft group. However, the failure load of both the distal and proximal host/graft conjunctions in the Eng‐allograft group was significantly lower than that of the autograft group with higher graft rupture at the host−graft junction. In conclusion, the decellularized allogenic intrasynovial tendon, when revitalized BMSCs and synovialized with cd‐SYN, demonstrates positive effects on digital function improvement and adhesion reduction. However, the healing at both proximal and distal graft/host junctions is far lower than the autograft. Further research is needed to enhance the healing capacity of allograft conjunctions, aiming to achieve a comparable level of healing seen with autografts.

Purpose To investigate the gliding resistance dynamics between the supraspinatus (SSP) tendon and the coracoacromial arch, both before and after subacromial decompression (anterolateral acromioplasty) and acromion resection (acromionectomy). Methods Using 4 fresh‐frozen cadaveric shoulders, acromion shapes were classified (2 type I and 2 type III according to Bigliani). Subacromial bursa and coracoacromial ligament maintenance replicated physiologic sliding conditions. Gliding resistance was measured during glenohumeral abduction (0° to 60°) in internal rotation (IR) and external rotation (ER). Peak gliding resistance between the SSP tendon and the coracoacromial arch was determined and compared between intact, anterolateral acromioplasty, and acromionectomy. Results Peak SSP gliding resistance during abduction in an intact shoulder was significantly higher in IR than in ER (4.1 vs 2.1 N, P < .001). The mean peak SSP gliding resistance during 0° to 60° glenohumeral abduction in IR in the intact condition was significantly higher compared with the subacromial decompression condition (4.1 vs 2.8 N, P = .021) and with the acromionectomy condition (4.1 vs 0.9 N, P < .001). During 0° to 60° glenohumeral abduction in ER, mean peak SSP gliding resistance in the intact condition was not significantly different compared with the subacromial decompression condition (2.1 vs 2.0 N, P = .999). The 2 specimens with a hooked (i.e. type III) acromion showed significantly higher mean peak SSP gliding resistance during glenohumeral abduction in IR and ER when compared with the 2 specimens with a flat (i.e. type I) acromion (IR: 5.8 vs 3.0 N, P = .006; ER: 2.8 vs 1.4 N, P = .001). Conclusions In this cadaveric study, peak gliding resistance between the SSP tendon and the coracoacromial arch during combined abduction and IR was significantly reduced after anterolateral acromioplasty and was significantly higher in specimens with a hooked acromion. Clinical Relevance The clinical benefit of subacromial decompression remains unclear. This study suggests that anterolateral acromioplasty might reduce supraspinatus gliding resistance in those with a hooked acromion and in the typical “impingement” position.

AbstractChordae tendineae, referred to as heart tendinous cords, act as tendons connecting the papillary muscles to the valves in the heart. Their role is analogous to tendons in the musculoskeletal system. Despite being exposed to millions of cyclic tensile stretches over a human's lifetime, chordae tendineae rarely suffer from overuse injuries. On the other hand, musculoskeletal tendinopathy is very common and remains challenging in clinical treatment. The objective of this study was to investigate the mechanism behind the remarkable durability and resistance to overuse injuries of chordae tendineae, as well as to explore their effects on flexor tenocyte biology. The messenger RNA expression profiles of chordae tendineae were analyzed using RNA sequencing and verified by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. Interestingly, we found that periostin (Postn) and fibroblast growth factor 7 (FGF7) were expressed at significantly higher levels in chordae tendineae, compared to flexor tendons. We further treated flexor tenocytes in vitro with periostin and FGF7 to examine their effects on the proliferation, migration, apoptosis, and tendon‐related gene expression of flexor tenocytes. The results displayed enhanced cell proliferation ability at an early stage and an antiapoptotic effect on tenocytes, while treated with periostin and/or FGF7 proteins. Furthermore, there was a trend of promoted tenocyte migration capability. These findings indicated that Postn and FGF7 may represent novel cytokines to target flexor tendon healing. Clinical significance: The preliminary discovery leads to a novel idea for treating tendinopathy in the musculoskeletal system using specific molecules identified from chordae tendineae.

Paediatric trigger finger is rare compared to adult trigger finger or paediatric trigger thumb, and the aetiology is unclear. Proposed causes include local trauma, anatomical anomalies and systemic conditions. The aim of the present study was to detail the anatomical causes of surgically treated paediatric trigger fingers and provide an operative algorithm based on the anatomical findings. A total of 76 trigger fingers in 38 patients were identified retrospectively at our institution between 1975 and 2022. In total, 41 fingers in 26 patients had anatomical variations. A nodular thickening on the tendon, similar to Notta’s nodule in trigger thumbs, was the most common anatomical cause. Abnormal decussation of the flexor digitorum superficialis tendon was the second most common variation. The recurrence rate was significantly lower after resection of one slip of the flexor digitorum superficialis tendon compared to other surgical techniques in these patients. We recommend that surgeons assess for possible anatomical variation during surgery for the trigger finger. Level of evidence: IV

AbstractSeveral tendon and ligament animal models were presented at the 2022 Orthopaedic Research Society Tendon Section Conference held at the University of Pennsylvania, May 5 to 7, 2022. A key objective of the breakout sessions at this meeting was to develop guidelines for the field, including for preclinical tendon and ligament animal models. This review summarizes the perspectives of experts for eight surgical small and large animal models of rotator cuff tear, flexor tendon transection, anterior cruciate ligament tear, and Achilles tendon injury using the framework: “Why, Who, What, Where, When, and How” (5W1H). A notable conclusion is that the perfect tendon model does not exist; there is no single gold standard animal model that represents the totality of tendon and ligament disease. Each model has advantages and disadvantages and should be carefully considered in light of the specific research question. There are also circumstances when an animal model is not the best approach. The wide variety of tendon and ligament pathologies necessitates choices between small and large animal models, different anatomic sites, and a range of factors associated with each model during the planning phase. Attendees agreed on some guiding principles including: providing clear justification for the model selected, providing animal model details at publication, encouraging sharing of protocols and expertise, improving training of research personnel, and considering greater collaboration with veterinarians. A clear path for translating from animal models to clinical practice was also considered as a critical next step for accelerating progress in the tendon and ligament field.

Allogenic tendons grafts sourced from intrasynovial tendons are often used for tendon reconstruction. Processing is achieved through repetitive freeze–thaw cycles followed by lyophilization. Soaking the lyophilized tendon in saline (0.9%) for 24 h is the standard practice for rehydration. However, data supporting saline rehydration over the use of other hydrating solutions are scant. The purpose of the current study was to compare the effects of different rehydration solutions on biomechanical properties of lyophilized tendon allograft. A total of 36 canine flexor digitorum profundus tendons were collected, five freeze–thaw cycles followed by lyophilization were performed for processing, and then divided into three groups rehydrated with either saline solution (0.9%), phosphate-buffered saline (PBS), or minimum essential medium (MEM). Flexural stiffness, tensile stiffness, and gliding friction were evaluated before and after allograft processing. The flexural moduli in both fibrous and fibrocartilaginous regions of the tendons were measured. After lyophilization and reconstitution, the flexural moduli of both the fibrocartilaginous and non-fibrocartilaginous regions of the tendons increase significantly in the saline and MEM groups (p < 0.05). Compared to the saline and MEM groups, the flexural moduli of the fibrocartilaginous and non-fibrocartilaginous regions of tendons rehydrated with PBS are significantly lower (p < 0.05). Tensile moduli of rehydrated tendons are significantly lower than those of fresh tendons for all groups (p < 0.05). The gliding friction of rehydrated tendons is significantly higher than that of fresh tendons in all groups (p < 0.05). There is no significant difference in either tensile moduli or gliding friction between tendons treated with different rehydration solutions. These results demonstrate that allograft reconstitution can be optimized through careful selection of hydrating solution and that PBS could be a better choice as the impact on flexural properties is lower.