Biomechanical effect of rotator cuff augmentation with an acellular dermal matrix graft: a cadaver study.

BACKGROUND: Acellular human dermal matrix grafts (Graftjacket; Wright Medical Technology, Arlington, TN, USA) are used clinically for rotator cuff augmentation without a detailed understanding of their biomechanical effects. The purpose of this study was to evaluate the effect of augmentation with dermal grafts on the biomechanical effects of rotator cuff repairs. METHODS: Nine matched pairs of human cadaveric shoulders were used. A single-row rotator cuff repair combined with an augmentation graft was performed on one shoulder, and a single-row repair was performed on the contralateral shoulder as a control. An acellular dermal matrix graft was sutured to the tendon medially and fixed to the humerus laterally. The constructs were preloaded at 10 N and then cyclically loaded between 10 and 180 N for 1000 cycles, followed by tensile testing to failure at 1.0 mm/s. FINDINGS: The maximum load of the augmentation group (560.2 N, SD 95.5) was greater than that of the control group (345.7 N, SD 60.8), while the linear stiffness of the augmentation group (65.2 N/mm, SD 15.6) was less than that of the control group (77.2 N/mm, SD 15.7). Reliable gap distance data were not obtained during cyclic loading in 5 of 9 augmented repairs due to the elasticity of the dermal matrix graft. INTERPRETATION: The dermal matrix graft augmentation increased the maximum load but did not increase the linear stiffness. The elasticity of the dermal matrix graft affected the biomechanical effects of the augmented rotator cuff repairs.

Biomechanical comparison of lesser tuberosity osteotomy versus subscapularis tenotomy in total shoulder arthroplasty.

BACKGROUND: Total shoulder arthroplasty is traditionally performed through an anterior deltopectoral exposure with subscapularis tenotomy. Postoperative subscapularis dysfunction is common and adversely affects clinical outcomes. Consequently, surgeon interest in lesser tuberosity osteotomy has grown in an effort to improve subscapularis repair strength. This study investigated the biomechanical strength of subscapularis tenotomy vs lesser tuberosity osteotomy in the setting of total shoulder arthroplasty. MATERIALS AND METHODS: Uncemented humeral prostheses were placed in 20 paired upper extremities from 10 cadavers. For each respective cadaver, 1 limb underwent lesser tuberosity osteotomy and the contralateral limb underwent subscapularis tenotomy. The cadaveric specimens then underwent cyclic displacement and maximum load to failure testing. RESULTS: The subscapularis tenotomy specimens exhibited significantly less cyclic displacement (0.8 mm) than the osteotomy group (1.8 mm), with a 95% confidence interval (CI) for the difference of 0.5 to 1.5 mm (P = 0.002). The maximum load to failure was 439 ± 96 N for tenotomy and 447 ± 89 N for osteotomy (95% CI for the difference of -58 to 75), which was not significant (P = .78). CONCLUSION: Lesser tuberosity osteotomy was not significantly stronger than subscapularis tenotomy in maximum load to failure testing, with minimal clinical significance set at 100 N. Subscapularis tenotomy repair showed statistically significant less cyclic displacement than lesser tuberosity osteotomy. Further research is needed to clarify how the biomechanical results immediately after subscapularis tenotomy and lesser tuberosity osteotomy correlate with clinical outcomes.

Triceps tendon properties and its potential as an autograft.

BACKGROUND: Although the triceps tendon has been used as a graft for ligament reconstruction about the elbow, and has been postulated to be useful as a graft in the treatment of massive rotator cuff tears, no data exists on the tensile properties of the triceps tendon. The purpose of this study was to define the tensile properties of the medial, lateral, and central thirds of the triceps tendon, in order to examine its potential as an autograft for upper extremity pathology. MATERIALS AND METHODS: Ten fresh frozen upper extremity specimens were used. The triceps tendon was dissected from its musculotendinous junction and left attached to its insertion at the olecranon. The tendon was split into thirds and its tensile properties were recorded using a materials testing machine. RESULTS: The lateral portion was significantly thinner and less stiff than the medial and central portions (P < .05). It failed at significantly lower ultimate load than the central portion (P < .05). There were no significant differences between the medial, central, and lateral portions of the triceps tendons with regards to ultimate stress (P = .20) or modulus of elasticity (P = .64). CONCLUSION: Data from the current study were compared to available literature regarding tensile properties of the rotator cuff and elbow ligaments. Both the medial and central portions of the triceps tendon offer sufficient strength to be used in the reconstruction of the rotator cuff or ligament reconstruction in the elbow.

Surface treatment with 5-fluorouracil after flexor tendon repair in a canine in vivo model.

BACKGROUND: Topical 5-fluorouracil has been reported to reduce adhesions in animal models of tenolysis. The purpose of this study was to investigate the effects of topical 5-fluorouracil on adhesion formation after tendon repairs were subjected to immediate postoperative rehabilitation in a canine model in vivo. METHODS: Sixty dogs were randomly assigned to either a 5-fluorouracil treatment (thirty dogs) or a control group (thirty dogs). Each treatment group was then divided into three survival time points: ten days, twenty-one days, and forty-two days. The second and fifth flexor digitorum profundus tendons from each dog were fully lacerated at the zone-II area and then were repaired. Passive motion therapy started at day 5 postoperatively and continued until the dogs were killed. The repaired tendons were evaluated for normalized work of flexion, gliding resistance, repair strength, gene expression for type-I and type-III collagen and transforming growth factor-beta1, and histological appearance. RESULTS: The normalized work of flexion of the repaired tendons treated with 5-fluorouracil was significantly lower than that of the repaired tendons without 5-fluorouracil treatment at ten days. However, there was no significant difference between treated and untreated tendons at twenty-one and forty-two days. There was also no significant difference in gliding resistance, repair failure strength, or stiffness between treated and untreated tendons at any time point, or in the gross or histological appearance of adhesions at the time of killing. The expression of types-I and III collagen and transforming growth factor-beta1 of the repaired tendon with 5-fluorouracil treatment was significantly lower than that of the tendons without treatment at ten days postoperatively, but not at twenty-one or forty-two days. CONCLUSIONS: Although 5-fluorouracil treatment can reduce adhesions in in vivo models of tenolysis, this treatment had only a transient effect in an in vivo model of tendon repair that included passive motion.

Optimal screw orientation for fixation of coronoid fractures.

OBJECTIVE: The aim of this study was to compare the fixation stability of coronoid fractures achieved by a screw inserted in the anteroposterior (AP) direction with that achieved by a screw inserted in the posteroanterior (PA) direction. METHODS: Eleven pairs of fresh-frozen cadaveric ulna were used. A coronoid fracture was simulated by transverse osteotomy at the midpoint of coronoid height. The specimens of a pair were then randomized to be fixed with an AP screw in one specimen and a PA screw in the other. Insertion torque, load to failure, and stiffness were measured under axial load with a material testing machine. RESULTS: PA screw placement yielded greater strength and stiffness of fixation than did AP placement. The mean load to failure was 184 N in the PA screw group and 131 N in the AP screw group (P < 0.05). The mean stiffness was 106 N/mm with PA screws and 76 N/mm with AP screws (P < 0.05). These differences were statistically significant despite the fact that the screw insertion torques was similar in PA screw (0.27 Nm) and AP screw (0.25 Nm) (P = 0.2). CONCLUSIONS: PA screw placement was biomechanically superior to AP screw placement. Together with the fact that it is clinically easier to insert and remove screw from the posterior ulna, these data indicate that optimal screw orientation for fixation of coronoid tip fracture is posterior to anterior direction.

Gliding resistance and strength of composite sutures in human flexor digitorum profundus tendon repair: an in vitro biomechanical study.

PURPOSE: Although the strength of a tendon repair is clearly important, the friction of the repair is also a relevant consideration. The purpose of this study was to characterize the frictional coefficient, gliding resistance, and breaking strength of suture materials and a suture construct commonly used for flexor tendon repair. METHODS: We measured the friction coefficients of 3-0 braided nylon enclosed in a smooth nylon outer shell (Supramid, S. Jackson, Alexandria, VA), 3-0 braided polyester coated with polybutilate (Ethibond, Ethicon, Somerville, NJ), and 3-0 braided polyester/monofilament polyethylene composite (FiberWire, Arthrex, Naples, FL) sutures. We also measured the gliding resistance, linear breaking strength, and resistance to gapping of zone 2 modified Pennington tendon repairs with the 2 lowest-friction sutures in 20 human cadaveric flexor digitorum profundus tendons. RESULTS: The braided polyester/monofilament polyethylene composite had a significantly lower friction coefficient (0.054) than either the coated polyester (0.076) or nylon (0.130) sutures. The gliding resistances of the repaired tendons with braided/monofilament polyethylene composite suture and those of coated, braided polyester were similar. The strength of the 2 repairs (force to produce a 2 mm gap) and resistance to gap formation were also not significantly different. CONCLUSIONS: Braided polyester composite is a low-friction suture material. However, when this suture was used for tendon repair with a locking suture technique, it did not show a significant effect on the gliding resistance and repair strength compared with the same repair using a coated polyester suture.

Lubricin surface modification improves tendon gliding after tendon repair in a canine model in vitro.

This study investigated the effects of lubricin on the gliding of repaired flexor digitorum profundus (FDP) tendons in vitro. Canine FDP tendons were completely lacerated, repaired with a modified Pennington technique, and treated with one of the following solutions: saline, carbodiimide derivatized gelatin/hyaluronic acid (cd-HA-gelatin), carbodiimide derivatized gelatin to which lubricin was added in a second step (cd-gelatin + lubricin), or carbodiimide derivatized gelatin/HA + lubricin (cd-HA-gelatin + lubricin). After treatment, gliding resistance was measured up to 1,000 cycles of simulated flexion/extension motion. The increase in average and peak gliding resistance in cd-HA-gelatin, cd-gelatin + lubricin, and cd-HA-gelatin + lubricin tendons was less than the control tendons after 1,000 cycles (p < 0.05). The increase in average gliding resistance of cd-HA-gelatin + lubricin treated tendons was also less than that of the cd-HA-gelatin treated tendons (p < 0.05). The surfaces of the repaired tendons and associated pulleys were assessed qualitatively with scanning electron microscopy and appeared smooth after 1,000 cycles of tendon motion for the cd-HA-gelatin, cd-gelatin + lubricin, and cd-HA-gelatin + lubricin treated tendons, while that of the saline control appeared roughened. These results suggest that tendon surface modification can improve tendon gliding ability, with a trend suggesting that lubricin fixed on the repaired tendon may provide additional improvement over that provided by HA and gelatin alone.

Mechanical strength of bone allografts subjected to chemical sterilization and other terminal processing methods.

Infectious disease transmission through the use of human donor allografts can be a catastrophic complication in an otherwise straightforward surgical procedure. The use of bone allograft in reconstructive orthopedic surgeries is increasing, yet severe complications, including death, can result if the transplanted tissues transmit a communicable disease to the tissue recipient. The BioCleanse tissue sterilization process is a fully automated, low-temperature chemical sterilization process that renders allograft tissue sterile. The purpose of this study was to evaluate the effect of a chemical tissue sterilization process on the mechanical strength of cortical bone allografts prior to implantation. Cylindrical cortical bone specimens were harvested from seven human cadaver donors and treated either by: chemical sterilization alone; chemical sterilization and terminal sterilization by gamma irradiation; chemical sterilization, lyophilization, terminal sterilization by STERRAD and rehydration; or untreated. The specimens were tested to failure in axial compression, diametral compression, shear, or bending. There were no significant differences in ultimate stress, strain, or fracture energy between the chemically sterilized and control groups in any of the testing modes.

Dextrose-induced subsynovial connective tissue fibrosis in the rabbit carpal tunnel: A potential model to study carpal tunnel syndrome?

In this pilot study, hypertonic dextrose solution was used to induce fibrosis of the subsynovial connective tissue (SSCT) and create an animal model of potential use in the study of carpal tunnel syndrome (CTS). The SSCT of the carpal tunnel in 15 New Zealand white rabbits were injected with 0.05 ml of 10% dextrose solution in 1 paw and 0.05 ml of saline in the contralateral paw, to serve as a control. The animals were killed at 1, 2, 4, 8, or 12 weeks. While the saline side showed minimal changes at any time period, the hypertonic dextrose side showed progressive noninflammatory SSCT fibrosis, with vascular proliferation and thickening of collagen bundles. Demyelination of the median nerve developed at 12 weeks after the injection on the dextrose side. These findings are similar to the progression of pathology noted in humans with CTS.

Effects of carpal tunnel release on the relative motion of tendon, nerve, and subsynovial connective tissue in a human cadaver model.

BACKGROUND: The purpose of this study was to evaluate the effect of flexor retinaculum division (simulated carpal tunnel release) on the relative motion of flexor tendon, subsynovial connective tissue, and median nerve in human cadaver specimens. METHODS: Using fluoroscopy, we measured the relative motion of middle finger flexor digitorum superficialis tendon, subsynovial connective tissue, and median nerve in twelve human cadavers with simulated fist motion. Measurements were obtained for three wrist positions: neutral; 60 degrees flexion; and 60 degrees extension. The shear index was defined as the difference in motion between two tissues (tendon, subsynovial connective tissue, or nerve) relative to tendon excursion, expressed as a percentage. After testing with an intact carpal tunnel, the flexor retinaculum was cut and the testing procedure was repeated. FINDINGS: With an intact flexor retinaculum, the wrist flexion position showed significantly less displacement for the subsynovial connective tissue and median nerve relative to tendon displacement, and thus the highest potential shear strain between subsynovial connective tissue-tendon, and tendon-nerve. The wrist extension position also had a significantly higher potential shear strain for tendon-nerve compared to the neutral position. After division of the flexor retinaculum, the differences in shear index among wrist positions were reduced. For the wrist flexion position, the subsynovial connective tissue and median nerve displacements significantly increased, indicating lower shear index values. INTERPRETATION: These findings suggest that division of flexor retinaculum reduces the potential shear strain and thus possibly the risk of shear injury to tissues with the carpal tunnel.

The effect of wrist position on the relative motion of tendon, nerve, and subsynovial connective tissue within the carpal tunnel in a human cadaver model.

The purpose of this study was to measure the effect of wrist position on the relative motion of the middle finger flexor digitorum superficialis (FDS) tendon, subsynovial connective tissue (SSCT), median nerve, and flexor retinaculum during simulated active finger motion. The relative motion of each tissue was measured by fluoroscopy in 10 human cadavers. Measurements were obtained for wrist positions of neutral (0 degree extension), 30 and 60 degrees of flexion, and 30 and 60 degrees of extension. The shear strain index (SSI) was defined as the difference in motion between two tissues (tendon, SSCT, or nerve) divided by tendon excursion, expressed as a percentage. The motion of the tendon, SSCT, and nerve in the 60 degree flexed position was significantly less than the motion in all other wrist positions (p < 0.001). The SSI at 60 degrees of flexion for tendon-SSCT and tendon-nerve were significantly increased compared with all other positions (p < 0.001). Because the SSCT and tendon are physically connected, a decrease in SSCT motion relative to the tendon would increase the shear strain on the SSCT with tendon motion. Thus, this result suggests that the SSCT may be predisposed to shear injury from activity done in 60 degrees of wrist flexion.

Lubricin surface modification improves extrasynovial tendon gliding in a canine model in vitro.

BACKGROUND: Lubricin is the principal lubricant in synovial fluid. Although lubricin has been identified in tendons, especially on the surface of intrasynovial tendons such as the flexor digitorum profundus tendon, its ability to improve tendon gliding is unknown. The purpose of this study was to investigate the effects of exogenously applied lubricin on the gliding of extrasynovial tendons in a canine model in vitro. METHODS: Forty peroneus longus tendons, along with the proximal pulley in the ipsilateral hind paw, were harvested from adult mongrel dogs. After the gliding resistance of the normal tendons was measured, the tendons were treated with one of the following solutions: saline solution, lubricin, carbodiimide derivatized gelatin (cd-gelatin), carbodiimide derivatized gelatin with hyaluronic acid (cd-HA-gelatin), or carbodiimide derivatized gelatin to which lubricin had been added in a second step (cd-gelatin plus lubricin). Tendon gliding resistance was measured for 1000 cycles of simulated flexion-extension motion of the tendon. Transverse sections of the tendons were examined qualitatively at 100x magnification to estimate surface smoothness after 1000 cycles. RESULTS: There was no significant difference in the gliding resistance between the tendons treated with saline solution and those treated with lubricin alone, or between the tendons treated with cd-HA-gelatin and those treated with cd-gelatin plus lubricin; however, the gliding resistance of the tendons treated with cd-gelatin plus lubricin was significantly lower than that of the tendons treated with saline solution, lubricin alone, or cd-gelatin alone (p < 0.05). After 1000 cycles of tendon motion, the gliding resistance of the tendons treated with cd-gelatin plus lubricin decreased 18.7% compared with the resistance before treatment, whereas the gliding resistance of the saline-solution-treated controls increased >400%. The tendon surfaces treated with cd-gelatin plus lubricin or with cd-HA-gelatin appeared smooth even after 1000 cycles of tendon motion, whereas the other surfaces appeared roughened. CONCLUSIONS: While the addition of lubricin alone did not affect friction in this tendon gliding model, the results indicate that lubricin may preferentially adhere to a tendon surface pretreated with cd-gelatin and, when so fixed in place, lubricin does have an important effect on tendon lubrication.

Self-assembled monolayer films of phosphonates for bonding RGD to titanium.

Modification of the implant surface with the Arg-Gly-Asp tripeptide (RGD) putatively facilitates osteoblast attachment for improved implant fixation in the laboratory. We compared the histomorphometric and mechanical performance of titanium implants coated with RGD using a novel interface of self-assembled monolayers of phosphonates (RGD/SAMP) and implants coated with RGD using the more conventional thiolate-gold interface (RGD/thiolate-gold). We hypothesized RGD/SAMP-coated implants would show greater bone ongrowth and implant fixation than RGD/thiolate-gold-coated ones. We implanted an RGD/SAMP-coated implant in one femur and an RGD/thiolate-gold-coated in the contralateral femur of 60 rats. At 2, 4, and 8 weeks after implantation, 10 rats were sacrificed for histologic evaluation and another 10 for biomechanical testing. Bone-implant ongrowth and implant force-to-failure of the two implants were similar at all times. Although RGD/SAMP-coated implants did not show superior bone ongrowth and implant fixation, RGD/SAMP-coated implants have at least equally good histomorphometric and mechanical in vivo performance as RGD/thiolate-gold-coated ones. Additional in vivo characterization of self-assembled monolayer films of phosphonates as interface to bond RGD to titanium is needed to explore its full potential and seems justified based on the results of this study.

WOUND-HEALING PROPERTIES OF TRANSFORMING GROWTH FACTOR ß (TGF-ß) INDUCIBLE EARLY GENE 1 (TIEG1) KNOCKOUT MICE.

Transforming growth factor beta (TGF-ß) has a broad effect on wound healing, but many questions remain about the regulation of TGF-ß during the healing process. TGF-ß inducible early gene 1 (TIEG1) is a primary response gene for TGF-ß that controls the activities of the TGF-ß/Smad pathway, the primary TGF-ß signaling pathway. The purpose of this study was to investigate the role of TIEG1 in cutaneous wound healing using TIEG1 knockout mice. The wound healing in TIEG1 knockout mice and wild-type controls was evaluated by wound breaking strength, Western blot, and histology at postoperative days 3, 7, and 14. Although re-epithelialization of both groups was similarly complete at day 7, the TIEG1 knockout mice had a significantly lower wound breaking strength than the controls at postoperative day 14. These results suggest that TIEG1 expression may be an important factor involved in the initiation and support of normal cutaneous wound healing.

Mechanical properties of intrasynovial and extrasynovial tendon fascicles.

BACKGROUND: Tendon grafting in tendon reconstruction often involves the interchange of intrasynovial and extrasynovial tendons. Although many studies have examined the cellular and biological differences between tendons of various sources, few have studied the mechanical properties of these two different types of tendons. The purpose of this study was to investigate the mechanical properties of intrasynovial and extrasynovial tendons. METHODS: Canine peroneus longus (extrasynovial) and flexor digitorum profundus (intrasynovial) tendons, further subdivided into intrasynovial tendinous and intrasynovial fibrocartilaginous segments, were used in the study. An indentation test was used to measure the compressive modulus. Tensile testing was performed on 400mum longitudinal sections. FINDINGS: The compressive modulus of the intrasynovial fibrocartilaginous segment was significantly higher than that of the intrasynovial tendinous segment, which was in turn significantly higher than that of the extrasynovial tendon (P<0.0001). The tensile modulus of extrasynovial tendon was significantly higher than that of intrasynovial fibrocartilaginous and intrasynovial tendinous segments (P<0.005). The tensile modulus of the intrasynovial fibrocartilaginous and tendinous segments was not significantly different (P=0.14). INTERPRETATION: The results suggest that extrasynovial tendons exhibit superior tensile properties but inferior compressive properties when compared to intrasynovial tendons, which is consistent with their biological role in situ, but which could lead to complications when these tendons are repositioned during tendon graft surgery.

Substrate adhesion affects contraction and mechanical properties of fibroblast populated collagen lattices.

Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure. The purpose of this study was to evaluate the effect of substrate adhesion on the contraction and mechanical properties of fibroblast populated collagen lattices. Bacteriological grade polystyrene (BGPS) plates and tissue culture polystyrene (TCPS) plates were used as substrates for incubation of fibroblast populated collagen lattices. Hydrophobicity of the polystyrene surfaces was measured by the static sessile contact angle method. Collagen lattice contraction was recorded for 2 weeks, after which the lattices were mechanically tested. The BGPS culture plate had a significantly larger contact angle and was more hydrophobic than the TCPS culture plate. Both hydrophobicity and peripheral detachment of the collagen gel significantly decreased the time lag before initiation of gel contraction and increased the strength of the fibroblast populated collagen lattices. Substrate adhesion affects the contractility and strength of cell seeded collagen gels. This information may be useful in developing tissue engineered tendons and ligaments.

The mechanical properties of the rabbit carpal tunnel subsynovial connective tissue.

The rabbit model is commonly used to study carpal tunnel syndrome (CTS). It has been proposed that the subsynovial connective tissue (SSCT) in the carpal tunnel may play a role in the etiology of CTS, but the material properties of the rabbit SSCT are unknown. The purpose of this study was to develop a method to measure the shear properties of the rabbit SSCT. In six rabbit cadaver forepaws, the excursion of the third digit flexor digitorum superficialis (FDS) and load to failure of the SSCT were measured in a custom device. The mean excursion to full flexion in this model was 7.08mm (S.D. 0.77). The mean shearing force at full flexion was 317 mN (S.D. 166). At full flexion percentage of maximum shear force in the SSCT was 54.5% (S.D. 19.4). The mean energy absorbed at full flexion was 0.29mJ (S.D. 0.31). The mean excursion needed to reach 5% of the maximum shear force was 3.04mm (S.D. 0.99). The testing model presented in this study demonstrates structural parameters to evaluate the shear properties of the SSCT in a rabbit model. The data presented could be used for estimating sample sizes in a more comprehensive study of the effect of CTS on the SSCT properties.

Effect of host response (incorporation, encapsulation, mixed incorporation and encapsulation, or resorption) on the tensile strength of graft-reinforced repair in the rat ventral hernia model.

OBJECTIVE: The objective of the study was to determine whether the elicited histologic response to synthetic and xenograft materials affected the tensile strength of mesh-reinforced repairs in the rat ventral hernia model. STUDY DESIGN: Hernias were repaired with Gynemesh, Pelvicol, Pelvisoft, or Surgisis (representing incorporation, encapsulation, mixed incorporation and encapsulation, or resorption responses) and were compared with a suture-plicated control. Six animals per group were killed at 1 and 3 months after graft implantation. Preimplantation tensile strength was also measured for each graft material and native rat abdominal wall. RESULTS: Before implantation, Pelvicol had significantly higher adjusted tensile strength when compared with the rat abdominal wall (P < .001) or the other graft materials (P

Evaluation of the material properties of the subsynovial connective tissue in carpal tunnel syndrome.

BACKGROUND: The purpose of this study was to determine the material properties of the normal carpal tunnel subsynovial connective tissue in response to shear stress. METHODS: The shear modulus and maximum shear strength were measured with a custom-made micro-tester in 10 specimens of subsynovial connective tissue from 10 wrists in eight patients with idiopathic carpal tunnel syndrome and in 10 specimens from five fresh frozen cadavers without a history of carpal tunnel syndrome. FINDINGS: The mean shear modulus was 22.8 (SD 15.4)kPa for the patient group and 2.7 (SD 1.8)kPa for the control group. The mean maximum shear strength was 54.6 (SD 20.3)kPa for the patient group and 23.3 (SD 10.7)kPa for the control group. The values for the patient group were significantly higher than the control group (P<0.05). INTERPRETATION: The material properties of subsynovial connective tissue are altered in patients with idiopathic carpal tunnel syndrome. The impact, if any, of these altered properties on carpal tunnel syndrome remains to be elucidated.

The effect of carbodiimide-derivatized hyaluronic acid and gelatin surface modification on peroneus longus tendon graft in a short-term canine model in vivo.

PURPOSE: We have recently reported that application of carbodiimide-derivatized hyaluronic acid and gelatin (cd-HA gelatin) to a peroneus longus tendon graft increased tendon graft gliding ability and decreased work of flexion compared with untreated grafts in a canine model in vivo. In this study, we investigated the effect of this modification on adhesions, stiffness, strength of the distal attachment, and fibroblast count. METHODS: A total of 24 dogs were used for this study. The peroneus longus tendons of each hind leg were grafted into the 2nd and 5th digits of one forepaw in each dog. One peroneus longus tendon was treated with cd-HA gelatin prior to grafting, and the other one was immersed in 0.9% saline solution as a control. Animals were killed 1, 3, or 6 weeks postoperatively. RESULTS: The adhesion score of cd-HA gelatin-treated tendons was significantly less than that in the saline-treated tendons at all time points. There was no significant difference in the indentation stiffness between HA- and saline-treated grafts at any time point. For the ultimate force at the distal attachment, there was a significant difference among the time points, with a steady increase over time, but no significant difference between treated and control tendons at any time point. There was no significant difference in fibroblast count between treated and control tendons at any time point. CONCLUSIONS: Although gross adhesion formation was less, there was no significant difference in strength at the distal tendon-bone interface, cellularity, or tendon graft stiffness when comparing saline-treated and cd-HA gelatin-treated tendon grafts in vivo.