The Contralateral Ankle Joint Is a Reliable Reference for Testing Syndesmotic Stability Using Bilateral External Torque CT.

BACKGROUND: Subtle chronic or latent instabilities are difficult to delineate with currently available diagnostic modalities and do not allow assessment of ligamentous functionality. The noninvasive bilateral external torque computed tomography (CT) was able to reliably detect syndesmotic lesions in a cadaveric study. The aim of the study was to test the external torque device in young, healthy subjects at 3 different torque levels and to demonstrate comparability with the contralateral side. METHODS: Ten healthy subjects without history of injury or surgery to the ankle joint were enrolled in this cross-sectional study. Four CT scans were performed. During the scans, the lower legs and feet were placed in an external torque device with predefined external rotation torques of 0, 2.5, 5, and 7.5 Nm. Five different radiographic measures of syndesmotic stability were measured: anterior distance (AD), tibiofibular clear space (TCS), posterior distance (PD), external rotation (ER), and ß angle. RESULTS: With increasing external torque, slight increases in AD, ER, and ß angle were observed, whereas TCS and PD decreased slightly. Large absolute differences were found between the healthy subjects for all measured parameters, regardless of the external torque applied. Differences from the contralateral side using the same external torque were minimal for all parameters, but smallest for AD with a maximum difference of 0.5 mm. CONCLUSION: Using the healthy contralateral ankle joint is appropriate for assessing syndesmotic stability based on minimal intraindividual side differences using the external torque device. Side differences >0.5 mm in AD and >0.9 mm in PD may be considered abnormal and may indicate significant instability of the syndesmosis. However, future studies are needed to define definitive cutoff values for relevant side differences in acute and chronic syndesmotic instability to guide clinicians in their treatment decisions.

Hyaluronic acid/PEO electrospun tube reduces tendon adhesion to levels comparable to native tendons - An in vitro and in vivo study.

A major problem after tendon injury is adhesion formation to the surrounding tissue leading to a limited range of motion. A viable strategy to reduce adhesion extent is the use of physical barriers that limit the contact between the tendon and the adjacent tissue. The purpose of this study was to fabricate an electrospun bilayered tube of hyaluronic acid/polyethylene oxide (HA/PEO) and biodegradable DegraPol® (DP) to improve the anti-adhesive effect of the implant in a rabbit Achilles tendon full laceration model compared to a pure DP tube. Additionally, the attachment of rabbit tenocytes on pure DP and HA/PEO containing scaffolds was tested and Scanning Electron Microscopy, Fourier-transform Infrared Spectroscopy, Differential Scanning Calorimetry, Water Contact Angle measurements, and testing of mechanical properties were used to characterize the scaffolds. In vivo assessment after three weeks showed that the implant containing a second HA/PEO layer significantly reduced adhesion extent reaching levels comparable to native tendons, compared with a pure DP implant that reduced adhesion formation only by 20 %. Tenocytes were able to attach to and migrate into every scaffold, but cell number was reduced over two weeks. Implants containing HA/PEO showed better mechanical properties than pure DP tubes and with the ability to entirely reduce adhesion extent makes this implant a promising candidate for clinical application in tendon repair.

Bilateral External Torque CT Reliably Detects Syndesmotic Lesions in an Experimental Cadaveric Study.

BACKGROUND: If tibiofibular syndesmotic injury is undetected, chronic instability may lead to persistent pain and osteoarthritis. So far, no reliable diagnostic method has been available. The primary objectives of this study were to determine whether defined lesions of the syndesmosis can be correlated with specific tibiofibular joint displacements caused by external rotational torque and to compare the performance of bilateral external torque computed tomography (BET-CT) and arthroscopy. Secondary objectives included an evaluation of the reliability of CT measurements and the suitability of the healthy contralateral ankle as a reference. METHODS: Seven pairs of healthy, cadaveric lower legs were tested and assigned to 2 groups: (1) supination-external rotation (SER) and (2) pronation-external rotation (PER). In the intact state and after each surgical step, an ankle arthroscopy and 3 CT scans were performed. During the scans, the specimens were placed in an external torque device with 2.5, 5.0, and 7.5 Nm of torque applied. RESULTS: The arthroscopic and CT parameters showed significant correlations in all pairwise comparisons. The receiver operating characteristic (ROC) curve analyses yielded the best prediction of syndesmotic instability with the anterior tibiofibular distance on CT, with a sensitivity of 84.1% and a specificity of 95.2% (area under the curve [AUC], 94.8%; 95% confidence interval [CI], 0.916 to 0.979; p < 0.0001) and with the middle tibiofibular distance on arthroscopy, with a sensitivity of 76.2% and specificity of 92.3% (AUC, 91.2%; 95% CI, 0.837 to 0.987; p < 0.0001). Higher torque amounts increased the rate of true-positive results. CONCLUSIONS: BET-CT reliably detects experimental syndesmotic rotational instability, compared with the healthy side, with greater sensitivity and similar specificity compared with the arthroscopic lateral hook test. Translation of these experimental findings to clinical practice remains to be established. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Stability of novel cow-hitch suture button coracoid bone graft fixation in Latarjet procedures: a biomechanical study.

BACKGROUND: The Latarjet procedure is widely used to address anterior shoulder instability, especially in case of glenoid bone loss. Recently, cortical suture button fixation for coracoid transfer has been used to mitigate complications seen with screw placement. The aim of this biomechanical study was to evaluate the stability of a novel and cost-effective cow-hitch suture button technique, designed to be performed through a standard open deltopectoral approach, and compare this to a well-established double suture button technique. MATERIALS AND METHODS: We randomly assigned 12 fresh frozen cadaveric shoulders to undergo the Latarjet procedure with either 4 suture button (S&N EndoButton) fixations (SB group; n = 6, age 72 ± 9.8 years) or cow-hitch suture button technique using a 1.7-mm FiberTape looped sequentially in 2 suture buttons (Arthrex Pectoralis Button) placed from anterior on the posterior glenoid (CH-SB group; n = 6, age 73 ± 9.3 years). After fixation, all shoulders underwent biomechanical testing with direct loading on the graft via a material testing system. Cyclic loading was performed for 100 cycles (10-100 N) to determine axial displacement with time; each graft was then monotonically loaded to failure. RESULTS: The maximum cyclic displacement was 4.3 ± 1.6 mm for the cow-hitch suture button technique and 5.0 ± 1.7 mm for the standard double suture button technique (P = .46). Ultimate load to failure and stiffness were, respectively, 190 ± 82 N and 221 ± 124 N/mm for the CH-SB technique and 172 ± 48 N and 173 ± 34 N/mm for the standard double SB technique (P = .66 and .43). The most common failure mode was suture cut-through at the anteroinferior aspect of the glenoid for both fixation groups. CONCLUSIONS: The cow-hitch suture button technique resulted in a similar elongation, stiffness, and failure load compared to an established double suture button technique. Therefore, this cost-effective fixation may be an alternative, eligible for open approaches, to the established double suture button techniques.

The Unloading Effect of Supramalleolar Versus Sliding Calcaneal Osteotomy for Treatment of Osteochondral Lesions of the Medial Talus: A Biomechanical Study.

Background: In patients with osteochondral lesion, defects of the medial talus, or failed cartilage surgery, a periarticular osteotomy can unload the medial compartment. Purpose: To compare the effects of supramalleolar osteotomy (SMOT) versus sliding calcaneal osteotomy (SCO) for pressure redistribution and unloading of the medial ankle joint in normal, varus-aligned, and valgus-aligned distal tibiae. Study Design: Controlled laboratory study. Methods: Included were 8 cadaveric lower legs with verified neutral ankle alignment (lateral distal tibial angle [LDTA] = 0°) and hindfoot valgus within normal range (0°-10°). SMOT was performed to modify LDTA between 5° valgus, neutral, and 5° varus. In addition, a 10-mm lateral SCO was performed and tested in each position in random order. Axial loading (700 N) of the tibia was applied with the foot in neutral alignment in a customized testing frame. Pressure distribution in the ankle joint and subtalar joint, center of force, and contact area were recorded using high-resolution Tekscan pressure sensors. Results: At neutral tibial alignment, SCO unloaded the medial joint by a mean of 10% ± 10% or 66 ± 51 N (P = .04) compared with 6% ± 12% or 55 ± 72 N with SMOT to 5° valgus (P = .12). The achieved deload was not significantly different (ns) between techniques. In ankles with 5° varus alignment at baseline, SMOT to correct LDTA to neutral insufficiently addressed pressure redistribution and increased medial load by 6% ± 9% or 34 ± 33 N (ns). LDTA correction to 5° valgus (10° SMOT) unloaded the medial joint by 0.4% ± 14% or 20 ± 75 N (ns) compared with 9% ± 11% or 36 ± 45 N with SCO (ns). SCO was significantly superior to 5° SMOT (P = .017) but not 10° SMOT. The subtalar joint was affected by both SCO and SMOT, where SCO unloaded but SMOT loaded the medial side. Conclusion: SCO reliably unloaded the medial compartment of the ankle joint for a neutral tibial axis. Changes in the LDTA by SMOT did not positively affect load distribution, especially in varus alignment. The subtalar joint was affected by SCO and SMOT in opposite ways, which should be considered in the treatment algorithm. Clinical Relevance: SCO may be considered a reliable option for beneficial load-shifting in ankles with neutral alignment or 5° varus malalignment.

Bioactive and Elastic Emulsion Electrospun DegraPol Tubes Delivering IGF-1 for Tendon Rupture Repair.

Tendon injuries can result in two major drawbacks. Adhesions to the surrounding tissue may limit the range of motion, while fibrovascular scar formation can lead to poor biomechanical outcomes. Prosthetic devices may help to mitigate those problems. Emulsion electrospinning was used to develop a novel three-layer tube based on the polymer DegraPol (DP), with incorporated insulin-like growth factor-1 (IGF-1) in the middle layer. Scanning electron microscopy was utilized to assess the fiber diameter in IGF-1 containing pure DP meshes. Further characterization was performed with Fourier Transformed Infrared Spectroscopy, Differential Scanning Calorimetry, and water contact angle, as well as through the assessment of mechanical properties and release kinetics from ELISA, and the bioactivity of IGF-1 by qPCR of collagen I, ki67, and tenomodulin in rabbit Achilles tenocytes. The IGF-1-containing tubes exhibited a sustained release of the growth factor up to 4 days and showed bioactivity by significantly upregulated ki67 and tenomodulin gene expression. Moreover, they proved to be mechanically superior to pure DP tubes (significantly higher fracture strain, failure stress, and elastic modulus). The novel three-layer tubes intended to be applied over conventionally sutured tendons after a rupture may help accelerate the healing process. The release of IGF-1 stimulates proliferation and matrix synthesis of cells at the repair site. In addition, adhesion formation to surrounding tissue can be reduced due to the physical barrier.