Background: The enthesis of the plantar fascia is thought to play an important role in stress dissipation. However, the potential link between entheseal thickening characteristic of enthesopathy and the stress-dissipating properties of the intervening plantar fat pad have not been investigated.
Purpose: This study was conducted to identify whether plantar fat pad mechanics explain variance in the thickness of the fascial enthesis in individuals with and without plantar enthesopathy.
Study Design: Case-control study; Level of evidence, 3.
Methods: The study population consisted of 9 patients with unilateral plantar enthesopathy and 9 asymptomatic, individually matched controls. The thickness of the enthesis of the symptomatic, asymptomatic, and a matched control limb was acquired using high-resolution ultrasound. The compressive strain of the plantar fat pad during walking was estimated from dynamic lateral radiographs acquired with a multifunction fluoroscopy unit. Peak compressive stress was simultaneously acquired via a pressure platform. Principal viscoelastic parameters were estimated from subsequent stress-strain curves.
Results: The symptomatic fascial enthesis (6.7 ± 2.0 mm) was significantly thicker than the asymptomatic enthesis (4.2 ± 0.4 mm), which in turn was thicker than the enthesis (3.3 ± 0.4 mm) of control limbs (P < .05). There was no significant difference in the mean thickness, peak stress, peak strain, or secant modulus of the plantar fat pad between limbs. However, the energy dissipated by the fat pad during loading and unloading was significantly lower in the symptomatic limb (0.55 ± 0.17) when compared with asymptomatic (0.69 ± 0.13) and control (0.70 ± 0.09) limbs (P < .05). The sonographic thickness of the enthesis was correlated with the energy dissipation ratio of the plantar fat pad (r = .72, P < .05), but only in the symptomatic limb.
Conclusion: The energy-dissipating properties of the plantar fat pad are associated with the sonograpic appearance of the enthesis in symptomatic limbs, providing a previously unidentified link between the mechanical behavior of the plantar fat pad and enthesopathy.
Background: The standard Weaver-Dunn reconstruction of the acromioclavicular (AC) joint does not provide adequate superoinferior or anteroposterior stability. Augmentation methods such as tape cerclage have been described. A new method of augmentation with the Arthrex TightRope is available.
Hypothesis: A Weaver-Dunn reconstruction augmented with the TightRope will provide superior superoinferior and anteroposterior stability to the AC joint as compared with a Weaver-Dunn reconstruction augmented with Mersilene fiber tape cerclage.
Study Design: Controlled laboratory study.
Methods: Six matched pairs of cadaveric shoulders underwent Weaver-Dunn AC joint reconstructions and were randomly assigned to receive either the TightRope device or tape cerclage augmentation. Translation in 2 planes was measured in the intact state under load and after 1 load cycle and 2000 load cycles.
Results: TightRope-augmented repair showed less superoinferior translation (mean ± standard error) than cerclage-augmented repair in initially repaired (1.6 ± 0.1 mm vs 5.0 ± 1.1 mm, P = 0.03) and cyclically loaded (2.1 ± 0.1 mm vs 5.8 ± 1.2 mm, P = 0.02) conditions. TightRope repairs were stiffer than the native ligaments in the superoinferior plane. Less anteroposterior translation was observed with TightRope versus cerclage augmentation (initially repaired, 6.8 ± 0.4 mm vs 18.8 ± 2.6 mm, P < 0.001; cycled, 15.0 ± 1.4 mm vs 28.3 ± 2.7 mm, P = 0.01), but neither method maintained normal anteroposterior laxity after 1500 cycles compared with the intact state.
Conclusion: Superoinferior and anteroposterior translation with TightRope augmentation was lower than with tape cerclage.
Clinical Relevance: TightRope augmentation of a Weaver-Dunn procedure could provide increased protection for AC joint reconstruction, allowing for earlier mobilization and more aggressive early rehabilitation. The potential clinical effect of additional tightening in the superoinferior direction beyond that of the native joint remains an issue for further study.
Background: Arthroscopic repair of anterior Bankart lesions is typically done with single-loaded suture anchors tied with simple stitch configuration.
Hypothesis: The knotless suture anchor will have similar biomechanical properties compared with two types of conventional suture anchors.
Study Design: Controlled laboratory study.
Methods: Fresh-frozen shoulders were dissected and an anteroinferior Bankart lesion was created. For phase 1, specimens were randomized into either simple stitch (SSA) or knotless suture anchors (KSA) and loaded to failure. For phase 2, specimens were randomized into 1 of 4 repair techniques and cyclically loaded then loaded to failure: (1) SSA, (2) suture anchor with horizontal mattress configuration, (3) double-loaded suture anchor with simple stitch configuration, or (4) KSA. Data recorded included mode of failure, ultimate load to failure, load at 2 mm of displacement, as well as displacement during cyclical loading.
Results: For phase 1, the load required to 2 mm displacement of the repair construct was significantly greater in SSA (66.5 ± 21.7 N) than KSA (35.0 ± 12.5 N, P = .02). For phase 2, there was a statistically significant difference in ultimate load to failure among the 4groups, with both the single-loaded suture anchor with simple stitch (184.0 ± 64.5 N), horizontal mattress stitch (189.0 ± 65.3N), and double-loaded suture anchor with simple stitch (216.7 ± 61.7 N) groups having significantly (P < .05) higher loads than the knotless group (103.9 ± 52.8 N). There was no statistically significant difference (P > .05) among the 4 groups in displacement after cyclical loading or load at 2 mm of displacement.
Conclusion: Both knotless and simple anchor configurations demonstrated similar single loads to failure (without cycling); however, the knotless device required less single load to displace 2 mm. All repair stitches, including simple, horizontal, and double-loaded performed similarly.
Clinical Relevance: The findings may suggest that with cyclical loading up to 25 N there is no difference in gapping greater than 2mm, but a macrotraumatic event may demonstrate a difference in fixation during the initial postoperative period. Additional in vivo studies are needed to determine whether these differences affect the integrity of the repair construct and, ultimately, the clinical outcome.
Background: The use of posterior capsular plication to decrease capsular volume and address capsular laxity for treatment of posterior instability, multidirectional instability, or as an additional technique in the treatment of anterior instability is common. Multiple different suturing techniques have been described.
Hypothesis: The simple stitch will have inferior biomechanical properties compared with either the horizontal mattress or figure-of-8 stitches for suture plication of the posteroinferior quadrant of the glenoid.
Study Design: Controlled laboratory study.
Methods: Twenty-one fresh-frozen shoulders with a mean age of 57.7 ± 12.3 years were randomized into capsulolabral plication of the posteroinferior quadrant using either simple stitch configuration, horizontal mattress configuration, or figure-of-8 configuration. Each shoulder was mounted onto a materials testing machine, preloaded to 5 N for 2 minutes, cycled from 5 to 25 N for 100 cycles (1 Hz), and then loaded to failure at 15 mm/min. Capsular displacement from the glenoid was determined using digital video analysis. Data recorded included mode of failure, ultimate load to failure, load at 2 mm of displacement, as well as displacement during cyclical loading (during the entire 100 cycles and during the final cycle only).
Results: There was a statistically significant difference (P < .0001) in mechanism of failure among the 3 groups with the simple stitch group failing more often in the capsular tissue than in the mattress and figure-of-8 sutures, which more commonly failed at the capsulolabral junction. There was no statistically significant difference (P > .05) among the 3 groups in gapping (displacement) after cyclical loading, load at 2 mm of displacement, or in ultimate load to failure.
Conclusion/Clinical Relevance: Based on these results, all 3 stitches can be used effectively for capsular plication, although the simple stitch may be preferred for the capsular plication because of technical ease and decreased trauma to the capsulolabral tissue.
