Citations

Purpose The purpose of this in vitro biomechanical study was to assess the effects of the remplissage procedure for small‐ and large‐sized Hill‐Sachs lesions (HSLs) on shoulder range of motion (ROM) with a special interest in the apprehension position. Methods HSLs of 50% and 100% of the glenoid width were simulated in 7 cadaveric shoulders as small and large lesions, respectively, and the postoperative condition was reproduced by placing suture anchors on the articular surface and tying down the infraspinatus at the medial edge of the would‐be lesion site. ROMs were measured in abduction, internal rotation, and external rotation with the humerus in the adducted and abducted position. In addition, the ROM was measured in the anterior apprehension position, in which 2 torques of external rotation and extension were applied simultaneously, and external rotation and horizontal extension ROMs were measured with the humerus in different abduction angles (20°, 40°, and 60°). Results For standard ROMs, the procedure for the 50% HSL maintained complete ROMs, whereas the procedure for the 100% HSL significantly decreased external rotation ROM with the humerus in both the adducted and abducted positions, as well as abduction ROM. In the apprehension position, remplissage for the 50% HSL decreased extension ROM with the humerus abducted to 40° and 60°. Remplissage for the 100% HSL significantly decreased both external and extension ROMs regardless of the humeral abduction angle. Conclusions In the cadaveric model with an intact humeral head and the simulated postoperative condition, the remplissage procedure for a large HSL caused significant restrictions in ROM of abduction in the scapular plane and external rotation with the humerus in both adduction and abduction. It also caused significant restrictions in both external rotation and extension ROMs in the apprehension position. Clinical Relevance The indication for the remplissage procedure for the larger HSL should be considered carefully, especially for the competitive throwing athlete who needs exceptional external rotation ROM for optimal overhead throwing performance.

One commonly reported complication of pyrolytic carbon arthroplasty at the proximal interphalangeal (PIP) joint is an annoying, painless, squeaking postoperatively. This squeak has been anecdotally associated with implant loosening or impending dislocation. The purpose of this study was to investigate the etiology of this squeaking. Proximal and distal components of the pyrolytic carbon PIP implant were inserted into foam bones and mounted onto an oscillating test device. We evaluated the effect of 96 combinations of load, velocity, contact angle, implant size, lubrication, and displacement amplitude over a total of 300 cycles for each condition. Sound analysis was performed on squeaking conditions. Fourteen conditions resulted in squeaking, all with a sound pattern similar to that noted clinically. Unlubricated, “dry” joints did not squeak. Squeaking most commonly occurred with fetal bovine serum lubrication, at higher loads, and at 0 deg hyperextension. Hyaluronic acid viscosupplementation stopped the squeaking in all cases.

The supraspinatus tendon consists morphologically of two sub‐regions, anterior and posterior. The anterior sub‐region is thick and tubular while the posterior is thin and strap‐like. The purpose of this study was to compare the structural and mechanical properties of the anterior and posterior sub‐regions of the supraspinatus tendon. The supraspinatus tendons from seven human cadaveric shoulders were morphologically divided into the anterior and posterior sub‐regions. Length, width, and thickness were measured. A servo‐hydraulic testing machine (MTS Systems Corporation, Minneapolis, MN) was used for tensile testing. The maximal load at failure, modulus of elasticity and ultimate tendon stress were calculated. Repeated measures were used for statistical comparisons. The mean anterior tendon cross‐sectional area was 47.3 mm2 and the posterior was 32.1 mm2. Failure occurred most often at the insertion site: anterior (5/7) and posterior (6/7). All parameters of the anterior sub‐region were significantly greater than those of the posterior sub‐region. The moduli of elasticity at the insertion site were 592.4 MPa in the anterior sub‐region and 217.7 MPa in the posterior (P = 0.01). The ultimate failure loads were 779.2 N in the anterior sub‐region and 335.6 N in the posterior (P = 0.003). The ultimate stresses were 22.1 MPa in the anterior sub‐region and 11.6 MPa in the posterior (P = 0.008). We recognized that the anterior and posterior sub‐regions of the SSP tendon have significantly different mechanical properties. In a future study, we need to evaluate how best to repair an SSP tendon considering these region‐specific properties. Clin. Anat. 27:702–706, 2014. © 2013 Wiley Periodicals, Inc.

SUMMARYFibrosis of the subsynovial connective tissue (SSCT) in the carpal tunnel is the most common histological finding in carpal tunnel syndrome (CTS). Fibrosis may result from damaged SSCT. Previous studies found that with low‐velocity (2 mm/s), tendon excursions can irreversibly damage the SSCT. We investigated the effect of tendon excursion velocity in the generation of SSCT damage. Nine human cadaver wrists were used. Three repeated cycles of ramp‐stretch testing were performed simulating 40%, 60%, 90%, and 120% of the middle finger flexor tendon superficialis physiological excursion with an excursion velocity of 60 mm/s. Energy and force were calculated and normalized by values obtained in the first cycle for each excursion level. Data were compared with low‐velocity excursion data. For high‐velocity excursions, a significant drop in the excursion energy ratio was first observed at an excursion level of 60% physiological excursion (p < 0.024) and that for low‐velocity excursions was first observed at 90% physiological excursion (p < 0.038). Furthermore, the energy ratio was lower at 60% for high velocities (p ≤ 0.039). Increasing velocity lowers the SSCT damage threshold. This finding may be relevant for understanding the pathogenesis of SSCT fibrosis, such as that accompanying CTS, and a relationship with occupational factors. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:123–128, 2014.

ABSTRACTNon‐inflammatory fibrosis of the subsynovial connective tissue (SSCT) is a hallmark of carpal tunnel syndrome (CTS). The etiology of this finding and its relationship to the development of CTS remain poorly understood. Recent studies have found that transforming growth factor‐β (TGF‐β) plays a central role in fibrosis. The purpose of this study was to investigate the expression of TGF‐β and connective tissue growth factor (CTGF), a downstream mediator of TGF‐β, in the pathogenesis of CTS. We compared SSCT specimens from 26 idiopathic CTS patients with specimens from 10 human cadaver controls with no previous diagnosis of CTS. Immunohistochemistry was performed to determine levels TGF‐β1, CTGF, collagen 1(Col1) and collagen 3 (Col3) expression. TGF‐β1 (p < 0.01), CTGF (p < 0.01), and Col3 (p < 0.01) were increased in SSCT of CTS patients compared with control tissue. In addition, a strong positive correlation was found between TGF‐β1 and CTGF, (R2 = 0.80, p < 0.01) and a moderate positive correlation between Col3 and TGF‐β1 (R2 = 0.49, p < 0.01). These finding suggest that there is an increased expression of TGF‐β and CTGF, a TGF‐β regulated protein, and that this TGF‐β activation may be responsible for SSCT fibrosis in CTS patients. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:116–122, 2014.

AbstractTendon‐to‐bone integration is a great challenge for tendon or ligament reconstruction regardless of use of autograft or allograft tendons. We mineralized the tendon, thus transforming the tendon‐to‐bone into a “bone‐to‐bone” interface for healing. Sixty dog flexor digitorum profundus (FDP) tendons were divided randomly into five groups: (1) normal FDP tendon, (2) CaP (non‐extraction and mineralization without fetuin), (3) CaPEXT (Extraction by Na2HPO4 and mineralization without fetuin), (4) CaPFetuin (non‐extraction and mineralization with fetuin), and (5) CaPEXTFetuin (extraction and mineralization with fetuin). The calcium and phosphate content significantly increased in tendons treated with combination of extraction and fetuin compared to the other treatments. Histology also revealed a dense mineral deposition throughout the tendon outer layers and penetrated into the tendon to a depth of 200 µm in a graded manner. Compressive moduli were significantly lower in the four mineralized groups compared with normal control group. No significant differences in maximum failure strength or stiffness were found in the suture pull‐out test among all groups. Mineralization of tendon alters the interface from tendon to bone into mineralized tendon to bone, which may facilitate tendon‐to‐bone junction healing following tendon or ligament reconstruction. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1713–1719, 2013

Many neck pain complaints are associated with degenerated discs in cervical spine. Disc degeneration (DD) consists of cascading stages of events with complex changes in disc tissue properties. This results in deterioration of the ability of the disc to perform its function normally. Several biomechanical and biochemical changes occur in the disc with degeneration. Increase in motion segment stiffness and peak stresses in the posterior annulus are some of the gross changes that occur in the disc with degeneration.

Tendons and ligaments are soft connective tissues that play an important role in the musculoskeletal system. The tendon transmits the concentrated tensions generated by the muscle to the bone, and the ligaments stabilize and guide the movement between bones connected at the articulating joints. To perform these tasks, these soft connective tissues are uniquely built to bear load transmission, but are flexible enough to allow the changing direction in their paths of alignment. To accomplish these requirements, the tendons and ligaments have a hierarchy of highly aligned collagen structures consisting of fibrils, fascicles and fibers, along with the ground substance of proteoglycans and glycolipids to form the tendon and ligament tissues.

Collagen fibers in the annulus fibrosus (AF) play a significant role in maintaining the disc mechanical behavior. In healthy discs, AF fibers are concentrically arranged in a zigzag fashion. Tensile loads are transmitted to these fibers when the disc is loaded in compression. As a result, disc bulging occurs. Initiation and progression of mild cervical disc degeneration (DD) has been the subject of clinical concern [1]. The mild DD is associated with structural interruption in laminar organization of fibers in partial AF regions and incomplete length of fibers is a major form of structural interruption in AF fibers [2]. Moreover, a loss of lamellar fiber structure contributes to the progression of spinal deformity [3]. Past research have documented the biomechanical role of complete length of fibers in governing a healthy disc behavior [4]; however, there is a lack of clear understanding as to how incomplete length of fibers in different AF regions affect overall disc biomechanics and how they may play a role in initiating the propagation of DD. The focus of the current study is to investigate the disc biomechanical response due to incomplete length of fibers in outer, middle, and inner AF regions.