Scapholunate Ligament: Comparing the Native Strength of the Ligament to an All-suture Anchor Construct.

Our aim was to compare the tensile strength of the native scapholunate ligament (SLL) with that of an all-suture anchor construct in a cadaveric model. The scaphoid and lunate were isolated, preserving all segments of the SLL. Using a servohydraulic testing machine, we increased the load until peak load-to-failure of the native SLL was reached in nine specimens (mean ± standard deviation, 273 ± 132 N). Using the same specimens, two JuggerKnot 1.4-mm suture anchors (Zimmer Biomet) were placed into the lunate and tensioned through transosseous tunnels in the scaphoid. Sutures were tied over the radial nonarticular aspect of the scaphoid. Load-to-failure testing was repeated. The mean peak load-to-failure for the all-suture anchor constructs was 172 ± 59 N versus 231 ± 117 N for the native group (p = 0.157). This represents approximately 75% of the native ligament strength. (Journal of Surgical Orthopaedic Advances 29(3):169-172, 2020).

Gastrocnemius recession: A cadaveric study of surgical safety and effectiveness.

Background and purpose - Many methods of gastrocnemius lengthening have been described, with different surgical challenges, outcomes, and risks to the sural nerve. Our aims were (1) to locate the gastrocnemius muscular-tendinous junction in relation to the mid-length of the fibula (from here on designated the mid-fibula), (2) to compare the dorsiflexion achieved with dorsal recession or ventral recession, and (3) to determine the risk of injury to the sural nerve during gastrocnemius recession. Methods - In 10 pairs of fresh-frozen adult cadaveric lower extremities transected above the knee, we measured dorsiflexion, performed dorsal or ventral gastrocnemius recession at the mid-fibula, and then measured the increase in dorsiflexion and fasciotomy gap. We noted the course of the sural nerve and whether the gastrocnemius muscle provided it with enough muscular coverage to protect it during recession. Results - Dorsal and ventral recession produced statistically (p < 0.05) and clinically significant mean increases in dorsiflexion with extended knee from 12° to 19°, but they were not statistically significantly different from each other in this measure or in fasciotomy gap size. At the mid-fibula, the sural nerve coursed superficially between both heads of the gastrocnemius muscle in 14 of 20 specimens. Sufficient gastrocnemius muscle coverage to protect the sural nerve was provided by the medial head in 18 of 20 specimens and by the lateral head in only 5 of 20 specimens. Interpretation - A ventral gastrocnemius recession proximal to the mid-fibula level poses less risk to the sural nerve than a recession at the mid-fibula. This procedure provides adequate lengthening (1-3 cm) and increased dorsiflexion (compared with baseline), with less risk to the sural nerve than is incurred with recession at the mid-fibular reference line.

Autologous distal clavicle versus autologous coracoid bone grafts for restoration of anterior-inferior glenoid bone loss: a biomechanical comparison.

BACKGROUND: Treating anterior glenoid bone loss in patients with recurrent shoulder instability is challenging. Coracoid transfer techniques are associated with neurologic complications and neuroanatomic alterations. The purpose of our study was to compare the contact area and pressures of a distal clavicle autograft with a coracoid bone graft for the restoration of anterior glenoid bone loss. We hypothesized that a distal clavicle autograft would be as effective as a coracoid graft. METHODS: In 13 fresh-frozen cadaveric shoulder specimens, we harvested the distal 1.0 cm of each clavicle and the coracoid bone resection required for a Latarjet procedure. A compressive load of 440 N was applied across the glenohumeral joint at 30° and 60° of abduction, as well as 60° of abduction with 90° of external rotation. Pressure-sensitive film was used to determine normal glenohumeral contact area and pressures. In each specimen, we created a vertical, 25% anterior bone defect, reconstructed with distal clavicle (articular surface and undersurface) and coracoid bone grafts, and determined the glenohumeral contact area and pressures. We used analysis of variance for group comparisons and a Tukey post hoc test for individual comparisons (with P <.05 indicating a significant difference). RESULTS: The articular distal clavicle bone graft provided the lowest mean pressure in all testing positions. The coracoid bone graft provided the greatest contact area in all humeral positions, but the difference was not significant. CONCLUSION: An articular distal clavicle bone graft is comparable in glenohumeral contact area and pressures to an optimally placed coracoid bone graft for restoring glenoid bone loss. LEVEL OF EVIDENCE: Basic Science Study; Biomechanics.

Biomechanical analysis of posterior intrafocal pin fixation for the pediatric supracondylar humeral fracture.

BACKGROUND: Controversy remains regarding the optimal fixation for displaced pediatric supracondylar humeral fractures. The clinical results of a recently described technique using a posterior intrafocal pin have been good to excellent. The aim of our study was to compare, in a cadaveric model, the stiffness provided by posterior intrafocal pin fixation versus crossed medial and lateral pin fixation and divergent lateral entry pin fixation for the treatment of Gartland-Wilkins type 3 supracondylar humeral fractures. METHODS: In 15 pairs of nonosteoporotic adult cadaver specimens, simulated Gartland-Wilkins type 3 supracondylar fractures were created and stabilized using: (1) the posterior intrafocal pin method; (2) medial and lateral crossed pins; or (3) 2 divergent lateral entry pins. Specimens were then subjected to internal rotation to measure the fixation stiffness of each construct. The effects of treatment and cycle number on torsional stiffness and peak torque were assessed for significance using a linear regression model with random effects to account for specimen pairing. Significance was set at P<0.05. RESULTS: The stiffest fixation was provided by crossed pins (2.4 N m/degree), followed by divergent lateral pins (1.9 N m/degree) and the posterior intrafocal pin (1.9 N m/degree), but none of the differences was statistically significant (P>0.9). Peak torque was not significantly different between fixations, although the trend suggested that crossed pins were strongest (34.6 N m), followed by divergent lateral pins (30.3 N m) and then posterior intrafocal pin fixation (26.1 N m). CONCLUSIONS: Our results suggest that posterior intrafocal pin fixation offers resistance to internal rotation equivalent to that of crossed medial and lateral pins and divergent lateral entry pins. CLINICAL RELEVANCE: The current biomechanical study supports the use of the posterior intrafocal posterior Kirschner pin for rotationally unstable supracondylar fractures because it is not significantly more compliant than standard techniques. LEVEL OF EVIDENCE: Level III.

Biomechanical analysis of endobutton versus screw fixation after Lisfranc ligament complex sectioning.

BACKGROUND: Our goal was to compare diastasis after endobutton and screw fixation after Lisfranc ligament complex sectioning. METHODS: Twenty-four (12 pairs) fresh-frozen cadaveric feet were assigned to endobutton or screw fixation and loaded to 343N. Displacement (first-second metatarsal bases) was measured in intact feet and after ligament sectioning (Lisfranc, medial-intermediate cuneiform ligaments), fixation, and 10,000 cycles. RESULTS: The mean change in diastasis for endobutton and screw fixation under initial loading was 1.0mm (95% CI, 0.2-1.9mm) and 0.0mm (95% CI, -0.4 to 0.4mm), respectively (p=0.017). After cyclic loading, diastasis decreased (mean, -0.7mm, 95% CI, -1.2 to -0.1mm) in the endobutton group but was unchanged in the screw group (p=0.035). CONCLUSIONS: Diastasis after endobutton fixation was significantly greater than after screw fixation under initial loading but did not increase further after cyclic loading.

Sacral mesh pullout strength based on suture location for sacrocolpopexy.

BACKGROUND: We sought to compare the pullout strengths of the sacral end of the sacrocolpopexy mesh when attached using one suture at the first versus second sacral vertebral level (S1 vs. S2) in female cadaveric pelvises. METHODS: The sacral vertebrae were isolated in 9 unembalmed female cadavers, and segments of polypropylene mesh were attached to the sacrum using stitches at either the S1 or S2 level. The free end of the mesh was pulled at a constant rate. Maximum tension prior to system failure was recorded for each specimen. Suture pullout strengths between the two groups were compared using the two-sample Wilcoxon rank-sum test. RESULTS: In all but one specimen, failure of the system occurred at the point of suture attachment to the anterior longitudinal ligament. Among the nine specimens, median pullout strengths were 7.49 lb (interquartile range 7.95) at S1 and 3.15 lb (interquartile range 2.975) at S2 (p = 0.028). CONCLUSION: The pullout strength of sutures used to attach the sacrocolpopexy mesh to the sacrum is significantly higher at the S1 level than at the S2 level.

The effectiveness of a program to reduce the rate of flash sterilization.

Flash sterilization of surgical instruments has been a common practice, but patient safety and quality assurance health care groups have recently recommended minimizing its use. Our goals were to describe the implementation and effectiveness of our institution's program for reducing the flash sterilization rate of instruments used for total hip and knee arthroplasties. We reviewed flash sterilization logs of all hip and knee arthroplasties from the program's implementation in July 2009 through August 2010 (N = 555) and calculated the monthly percentage of cases using flash sterilization. From the first to the last month, the amount of flash sterilization decreased significantly (P < .05): 6 of 34 to 0 of 41, respectively. Our results show that the rate of flash sterilization can be reduced with this strategic program.

Enhanced biomechanical stiffness with large pins in the operative treatment of pediatric supracondylar humerus fractures.

BACKGROUND: Various pin configurations have been recommended for the treatment of supracondylar humerus fractures on the basis of the choice between stability versus the risk of iatrogenic nerve injury. However, little attention has been paid to pin size. The purpose of this study was to evaluate the stability of large (2.8 mm or 0.110 inch) and small (1.6 mm or 0.062 inch) pin constructs in 6 configurations. METHODS: A transverse fracture pattern was created by sectioning synthetic humeri in the midolecranon fossa. The specimens were then reduced and pinned in one of 6 configurations: 2 small pins (Kirschner wires) placed crossed or lateral divergent, 2 large pins (Steinmann pins) placed crossed or lateral divergent, or 3 small pins placed crossed or lateral divergent. All specimens were then tested in sagittal extension bending. We investigated the effect of pin configuration and cycle on the sagittal stiffness using multiple linear regression. RESULTS: The 2 small lateral divergent pin configuration was significantly less stable than small crossed pins and large pins in a crossed or a lateral configuration. The addition of a third (lateral) pin to the small crossed pin construct made it significantly less stable than 2 large crossed pins. Although the stability between the remaining configurations was not significantly different, the 2 large crossed pins required the greatest torque to rotate the fragment 20 degrees. There was a significant reduction in torque as a function of cycle, suggesting a loss of fixation during cycling (P<0.05). CONCLUSIONS: Large pins (2.8 mm) in any configuration and the placement of small pins (1.6 mm) in a crossed configuration provided more stable reduction in sagittal extension bending than did the conventional 2 small pins in a lateral divergent pin configuration. The most stable configurations involve crossing the medial and lateral pins. CLINICAL RELEVANCE: There are more stable options than the traditional 2 small lateral pin configuration for fixation of unstable supracondylar fractures. The addition of a third pin is not always advantageous.

Biomechanical analysis suggests early rehabilitation is possible after single-incision EndoButton distal biceps repair with FiberWire.

PURPOSE: Previous studies that have encouraged early postoperative motion after distal biceps repair shows little agreement on exactly when activity should be resumed after surgery or on the level of weight restriction that should be used. The aim of the current study was to define a service load that would permit, without failure, 2,000 cycles of immediate motion after single-incision EndoButton distal biceps repair with FiberWire. METHODS: In each of 15 cadaveric elbows, the distal biceps tendon was divided at its insertion and then repaired using a single-incision EndoButton technique with FiberWire. The repairs were then challenged according to the "staircase method" by cyclically loading the biceps tendon, so that the forearm flexed between 0° and 90°. RESULTS: The mean failure load of the repair was 166.7 N (95% confidence interval, 132.6-200.8). The data suggested that a 0.9 kg (9-N) weight at the hand was the limit for a 2,000-cycle early rehabilitation protocol after repair of a ruptured distal biceps tendon via a single-incision EndoButton repair technique. CONCLUSION: Early active motion with a 0.9-kg weight restriction may therefore be possible in those patients undergoing distal biceps tendon repair using this technique.

Triceps tendons: a biomechanical comparison of intact and repaired strength.

HYPOTHESIS: Our hypothesis was that the autograft-augmented direct repair of torn triceps tendons would have strength superior than that of direct repair when compared to the strength of intact distal triceps tendons. MATERIALS AND METHODS: The strength of the intact distal triceps tendon in 8 unpaired, fresh frozen cadaver specimens was measured to tendon failure by uniaxial tension in the sagittal plane. The torn triceps tendons were then repaired by direct repair (sutures through drill holes) or an autograft-augmented direct repair. Each tendon repair was biomechanically tested to failure, and load to displacement curves and the site of tendon failure were recorded. Tendon strength after each repair was compared with that of the other repair technique and with that of the intact triceps tendon. Significance was set at P < .05. RESULTS: Average failure loads for intact, direct repair, and augmented repair tendons were 1741, 317, and 593 N, respectively; augmented repairs were significantly stronger than direct repairs. In the intact tendon, failure occurred at the insertion site through a tear at the bone tendon interface or through a small cortical avulsion. In the repaired tendons, all but 1 failure occurred through the suture; 1 augmented repair failed first at the tendon and then through the suture. DISCUSSION: There is a paucity of clinical data regarding the optimal repair for distal triceps avulsion. We found that triceps repair affords less strength than the intact tendon, but augmented repair was nearly twice as strong as that of direct repair. Augmented repair may allow earlier range of motion, weightbearing, and rehabilitation, theoretically decreasing complications associated with the procedure. CONCLUSIONS: Augmented triceps repair is superior to direct triceps repair for a distal triceps avulsion produced in a cadaver model.

Knee arthrotomy repair with a continuous barbed suture: a biomechanical study.

We compared knee arthrotomy closures using interrupted biodegradable sutures and running bidirectionally barbed sutures in cadaveric specimens subjected to cyclic loading. During the initial 2000 flexion cycles, both groups maintained closure and no suture ruptured. Suture throws were then sequentially cut to weaken the repairs, and the knees were cyclically flexed after each cut. Both types of suture repairs survived the cutting of the first throw or stitch and subsequent cyclical testing. However, there was a significant difference in the repairs after multiple cuts (log-rank test, P < .003). None of the knees in the interrupted suture group survived more than 3 cuts, whereas in the barbed repair group, it took the severing of as many as 7 throws for failure to occur.

Sagittal plane alignment affects the strength of pin fixation in supracondylar humerus fractures.

ABSTRACT: Closed reduction with percutaneous pin fixation is commonly used to treat pediatric supracondylar humerus fractures. Various pin configurations of varying biomechanical strength have been described. However, to our knowledge, no biomechanical study has focused on pin alignment in the sagittal plane. Our goal was to compare the stability of fixation using 3 different pin constructs: 3 lateral pins diverging in the coronal plane but parallel in the sagittal plane (3LDP), 3 lateral pins diverging in the coronal and sagittal planes (3LDD), and 2 crossed pins (1 medial and 1 lateral).Transverse fractures were made through the olecranon fossa of 48 synthetic humeri, which were then reduced and pinned in the 3LDP, 3LDD, and crossed-pin configurations (16 specimens per group) using 1.6-mm Kirschner wires. The sagittal plane pin spread was significantly greater in the 3LDD group than in the 3LDP group, whereas we found no difference in the coronal plane. Sagittal extension testing was performed from 0° to 20° at 1°/s for 10 cycles using a mechanical torque stand. The torque required to extend the distal fragment 20° from neutral was compared between groups using one-way analysis of variance with multiple comparison post-hoc analysis. P values ≤.05 were considered significant.The 3LDD configuration was more stable than the 3LDP and crossed-pin configurations. The mean torque required to displace the pinned fractures was 5.7 Nm in the 3LDD group versus 4.1 Nm in the 3LDP group and 3.7 Nm in the crossed-pin group (both, P < .01). We found no difference in stability between the 3LDP and crossed-pin groups (P = .45).In a synthetic biomechanical model of supracondylar humerus fracture, sagittal alignment influenced pin construct stability, and greater pin spread in the sagittal plane increased construct stability when using 3 lateral pins. The lateral pin configurations were superior in stability to the crossed-pin configuration.Level of Evidence: Level V.

Using the Remnant Anterior Cruciate Ligament to Improve Knee Stability: Biomechanical Analysis Using a Cadaveric Model.

BACKGROUND: Injured anterior cruciate ligament (ACL) tissue retains proprioceptive nerve fibers, vascularity, and biomechanical properties. For these reasons, remnant ACL tissue is often preserved during the treatment of ACL injuries. PURPOSE: To assess through a cadaveric model whether reorienting and retensioning the residual ACL via an osteotomy improves knee stability after partial ACL tear, with substantial remnant tissue and intact femoral and tibial attachments. STUDY DESIGN: Controlled laboratory study. METHODS: In 8 adult cadaveric knees, we measured anterior tibial translation and rotational laxity at 30° and 90° of flexion with the ACL in its native state and in 3 conditions: partial tear, retensioned, and ACL-deficient. The partial-tear state consisted of a sectioned anteromedial ACL bundle. RESULTS: In the native state, the translation was 10 ± 2.7 mm (mean ± SD) at 30° of flexion and 8.4 ± 3.6 mm at 90° of flexion. Anterior translation of the knees in the partial-tear state (14 ± 2.7 mm at 30° and 12 ± 2.7 mm at 90°) was significantly greater than baseline (P < .001 for both). Translation in the ACL-retensioned state (9.2 ± 1.7 mm at 30° and 7.2 ± 2.1 mm at 90°) was significantly less than in the ACL-deficient state (P < .001 for both), and translation was not significantly different from that of the intact state. For ACL-deficient knees, translation (20 ± 4.3 mm at 30° and 16 ± 4.4 mm at 90°) was significantly greater than all other states (P < .001 for all). Although rotational testing demonstrated the least laxity at 30° and 90° of flexion in the retensioned and intact states and the most laxity in the ACL-deficient state, rotation was not significantly different among any of the experimental states. CONCLUSION: In a cadaveric model of an incomplete ACL tear, a reorienting and retensioning core osteotomy at the tibial insertion of the remnant ACL improved anteroposterior translation of the knee without compromising its rotational laxity. CLINICAL RELEVANCE: The findings of this study support the concept of ACL tissue reorienting and retensioning in the treatment of ACL laxity as an area for future investigation.

Open Biceps Tenodesis: A Biomechanical Comparison of 6 Fixation Techniques.

Tenodesis is used to treat pathology of the long head of the biceps tendon. The authors evaluated the biomechanical properties of 6 techniques for biceps tenodesis fixation. The authors dissected 42 fresh-frozen cadaveric shoulders (mean age, 71±9.8 years; 69% male specimens), leaving the proximal humerus, proximal biceps tendon, and pectoralis major insertion. Specimens were randomized to undergo biceps tenodesis with one of the following: (1) an interference screw; (2) a cortical button; (3) a double-loaded 2.9-mm polyetheretherketone anchor (DL-2.9); (4) a double-loaded 1.9-mm all-suture anchor (DL-1.9); (5) a single-loaded 1.7-mm all-suture anchor (SL-1.7); or (6) soft tissue tenodesis. Specimens then underwent load-to-failure axial traction testing. A generalized linear and latent mixed model with a random-effects term was used to account for specimen pairing. Mean failure loads ranged from 136 N (95% confidence interval, 103-169 N) in the cortical button group to 79 N (95% confidence interval, 58-99 N) in the interference screw group. Failure occurred most often when fixation sutures pulled out of the tendon; however, 7 specimens failed elsewhere. No significant differences in ultimate failure load were found by treatment group. The interference screw group showed significantly more weakness than the cortical button and DL-2.9 groups. Tendon quality and suture parameters are likely more important than the fixation technique in determining failure load. [Orthopedics. 2020;43(2):e102-e108.].

Suture-button versus screw fixation in a syndesmosis rupture model: a biomechanical comparison.

BACKGROUND: Flexible suture-button devices are used to stabilize the distal tibiofibular joint after syndesmotic rupture, but little is known about how they affect fibular motion during cyclic physiological loading. This study examined how much fibular motion occurs during cyclic loading of ankles repaired with suture-buttons or screws relative to one with intact ligaments. MATERIALS AND METHODS: Ten pairs of cadaveric legs with intact ligaments were tested in axial compression (750 N), external rotational torque (7.5 Nm), and a combination thereof. Fibular rotation and translation in the sagittal and frontal planes were measured with linear variable displacement transducers. Then we sectioned the anterior tibiofibular, posterior tibiofibular, deltoid, and interosseous ligaments. Ankles were repaired with suture-buttons or a 3.5-mm screw through four-cortices. The ankles were tested for 10,000 cycles using the same loading protocol. Surviving ankles were brought to failure by increasing external rotation (1 degree/sec). Data from the linear variable differential transducers were used to calculate fibular motion at 100, 1,000, 5,000, and 10,000 cycles. RESULTS: There was no significant difference in the effect of the suture-button or screw for translation in the sagittal or coronal plane or for rotation about the fibular axis. The screw repair had a significantly greater (p = 0.02) failure torque (median, 26.5 Nm; inner quartile range, 25.7 to 35.2 Nm) than did the suture-button repair (median, 23.6 Nm; inner quartile range, 16.5 to 25.6 Nm). CONCLUSION: The fibular motion that occurs during cyclic loading appears to be similar for the suture-button and syndesmotic screw. Motion in both constructs was similar, but neither restored native ankle motion. CLINICAL RELEVANCE: It appears the suture-button behaves similarly to the syndesmotic screw in the syndesmotic rupture injury model tested. Clinical trials are needed to determine how the device performs in vivo.

Biomechanical comparison of two headless compression screws for scaphoid fixation.

This study compared compression generation between two headless compression screws: the Synthes 3.0-mm and the Acutrak standard. Twenty scaphoids were harvested from 10 pairs of fresh cadaveric forearms. A washer-shaped load cell was inserted between the halves of each scaphoid created by a simulated fracture via osteotomy. One scaphoid of each pair was tested with the Synthes and the other with the Acutrak. Parameters of interest were peak screw torque and fracture site compression. Differences in parameters of interest were checked for significance (p < .05) with paired t tests. No significant differences were shown in mean (+/- standard deviation) peak torque (57 +/- 28 Ncm vs. 55 +/- 32 Ncm; p < .84), compression immediately after insertion (119 +/- 54 N vs. 91 +/- 37 N; p < .15), or compression 5 min after insertion (32 +/- 30 N vs. 38 +/- 24 N; p < .61) between the Synthes and Acutrak screw fixations, respectively. The choice between these two screws to stabilize scaphoid waist fractures should be based on parameters other than compression generation, such as size, availability, cost, and ease of use of the implant.

Percutaneous screw configuration versus perimeter plating of calcaneus fractures: a cadaver study.

BACKGROUND: Percutaneous screw configuration has been used clinically to reduce the high rate of wound complications associated with the extensile approach of standard open reduction and internal plate fixation. The aim of this cadaveric biomechanical study was to compare the strength of the standard perimeter plating with that of the percutaneous screw configuration for a Sanders type-2B calcaneus fracture. MATERIALS AND METHODS: Ten pairs of fresh-frozen cadaveric lower limbs were prepared and osteotomized to create a Sanders type-2B fracture. Of each pair, one specimen underwent open reduction and internal fixation with standard perimeter plating; the other was stabilized with the percutaneous screw configuration. Each foot was compressed axially via the talar dome (1 mm/sec) until failure occurred. Differences in treatment groups were analyzed for significance (p < 0.05) using paired t-tests. RESULTS: Construct stiffness was 158 +/- 85 and 113 +/- 60 N/mm for the plate and percutaneous fixation, respectively (p = 0.18). Failure occurred at an average of 1156 +/- 513 and 1064 +/- 540 N for the plate and percutaneous construct, respectively (p = 0.65). CONCLUSION: The results suggest that open reduction and internal fixation with percutaneous screw configuration for Sanders type-2B calcaneus fractures provides a strength similar to that of perimeter plating. CLINICAL RELEVANCE: Percutaneous screw fixation of calcaneus fractures may provide fracture reduction similar to plate fixation.

Pullout strength of standard vs. cement-augmented rotator cuff repair anchors in cadaveric bone.

BACKGROUND: We evaluate a novel method of rotator cuff repair that uses arthroscopic equipment to inject bone cement into placed suture anchors. A cadaver model was used to assess the pullout strength of this technique versus anchors without augmentation. METHODS: Six fresh-frozen matched pairs of upper extremities were screened to exclude those with prior operative procedures, fractures, or neoplasms. One side from each pair was randomized to undergo standard anchor fixation with the contralateral side to undergo anchor fixation augmented with bone cement. After anchor fixation, specimens were mounted on a servohydraulic testing system and suture anchors were pulled at 90° to the insertion to simulate the anatomic pull of the rotator cuff. Sutures were pulled at 1 mm/s until failure. FINDINGS: The mean pullout strength was 540 N (95% confidence interval, 389 to 690 N) for augmented anchors and 202 N (95% confidence interval, 100 to 305 N) for standard anchors. The difference in pullout strength was statistically significant (P < 0.05). INTERPRETATION: This study shows superior pullout strength of a novel augmented rotator cuff anchor technique. The described technique, which is achieved by extruding polymethylmethacrylate cement through a cannulated in situ suture anchor with fenestrations, significantly increased the ultimate failure load in cadaveric human humeri. This novel augmented fixation technique was simple and can be implemented with existing instrumentation. In osteoporotic bone, it may substantially reduce the rate of anchor failure.

Biomechanical comparison of the interosseous tibiofibular ligament and the anterior tibiofibular ligament.

BACKGROUND: The mechanical importance of the interosseous tibiofibular ligament of the ankle is unclear. The purpose of the current study was to compare the stiffness and strength of the interosseous tibiofibular ligament to that of the anterior tibiofibular ligament. METHODS: Twelve pairs of ankles were obtained from the Maryland State Anatomy Board. All soft tissue was removed except for the interosseous tibiofibular ligament in one ankle of each pair and the anterior tibiofibular ligament in the contralateral ankle. The assignment of which ligament would be excised in the right or left ankle of each pair was random. The specimens were potted as bone-ligament-bone preparations and mounted in a servohydraulic testing machine so that the ligament's long axis was coincident with the actuator. Specimens were elongated at 0.5 mm/s until rupture. Failure load and failure site were recorded, and stiffness was calculated. Stiffness and failure loads were compared with a paired t-test. Significance was set at p < 0.05. RESULTS: The interosseous ligament was significantly stiffer (234 +/- 122 N/mm) than the anterior tibiofibular ligament (162 +/- 64 N/mm). The mean failure load of the interosseous tibiofibular ligament (822 +/- 298 N) was significantly greater than that of the anterior tibiofibular ligament (625 +/- 255 N). CONCLUSIONS: The interosseous tibiofibular ligament is stiffer and stronger than the anterior tibiofibular ligament. CLINICAL RELEVANCE. The current study suggests that the interosseous ligament plays an important role in the stability of the ankle, and its status should be part of the diagnostic evaluation in syndesmotic instability.

Pullout strength of cement-augmented and wide-suture transosseous fixation in the greater tuberosity.

BACKGROUND: Obtaining strong fixation in low-density bone is increasingly critical in surgical repair of rotator cuff tears because of the aging population. To evaluate two new methods of improving pullout strength of transosseous rotator cuff repair in low-density bone, we analyzed the effects of 1) using 2-mm suture tape instead of no. 2 suture and 2) augmenting the lateral tunnel with cement. METHODS: Eleven pairs of osteopenic or osteoporotic cadaveric humeri were identified by dual-energy x-ray absorptiometry. One bone tunnel and one suture were placed in the heads of 22 specimens. Five randomly selected pairs were repaired with no. 2 suture; the other six pairs were repaired with 2-mm suture tape. One side of each pair received lateral tunnel cement augmentation. Specimens were tested to suture pullout. Data were fitted to multivariate models that accounted for bone mineral density and other specimen characteristics. FINDINGS: Two specimens were excluded because of knot-slipping during testing. Use of suture tape versus no. 2 suture conferred a 75-N increase (95% CI: 37, 113) in pullout strength (P<0.001). Cement augmentation conferred a 42-N improvement (95% CI: 10, 75; P=0.011). Other significant predictors of pullout strength were age, sex, and bone mineral density. INTERPRETATION: We show two methods of improving the fixation strength of transosseous rotator cuff repairs in low-density bone: using 2-mm suture tape instead of no. 2 suture and augmenting the lateral tunnel with cement. These methods may improve the feasibility of transosseous repairs in an aging patient population.