Limited-Open Achilles Tendon Repair Using Locking Sutures Versus Nonlocking Sutures: An In Vitro Model

BACKGROUND

Several limited-open Achilles tendon repair techniques that use locking or nonlocking sutures have been developed, but direct comparisons of in vitro mechanical properties have not yet been reported in the literature. It was our hypothesis that loads applied to the repaired Achilles tendon would be better resisted by limited-open techniques that use locking stitches compared with limited-open repairs that use nonlocking stitches.

METHODS

The Achilles tendons of 31 fresh-frozen cadaver lower limbs were incised 4 cm proximal to the calcaneal insertion. Tendons were then repaired using 1 of 2 limited-open Achilles tendon repair tools, one using 3 nonlocking sutures and the other using a combination of locking and nonlocking sutures. Repaired specimens were cycled to 1000 cycles from 20 to 100 N and from 20 to 190 N followed by a single load to failure test. Nonparametric analyses were performed to compare the number of cycles to gapping and total load to failure between the 2 repair techniques.

RESULTS

During cyclic loading, more cycles occurred prior to detection of 2-mm and 9.5-mm gaps in the locking suture construct compared with the nonlocking suture construct ( P = .012 and P = .005, respectively). There was no difference in the number of cycles to a gap of 5 mm ( P = .053). The locking suture construct also resisted a significantly greater load to failure compared with the nonlocking suture construct ( P < .001; median 385.0 and 299.6 N, respectively).

CONCLUSION

Limited-open repair techniques using locking sutures provided greater construct strength under both cyclic and ultimate loads compared with a repair technique that used only nonlocking sutures.

CLINICAL RELEVANCE

Limited-open Achilles tendon repairs using locking sutures are better able to resist forces simulating early accelerated rehabilitation than repairs using nonlocking sutures.

Flexor tendon repairs: techniques, eponyms, and evidence

The evolution in surgical technique and suture technology has provided an abundance of options for flexor tendon repairs. Multiple biomechanical studies have attempted to identify the best surgical technique based on suture properties, technical modifications, and repair configurations. However, the burgeoning amount of research on flexor tendon repairs has made it difficult to follow, and no gold standard has been determined for the optimal repair algorithm. Therefore, it seems that repairs are usually chosen based on a combination of familiarity from training, popularity, and technical difficulty. We will discuss the advantages, disadvantages, and technical aspects of some of the most common core flexor tendon repairs in the literature. We will also highlight the nomenclature carried through the years, drawings of the repairs referred to by that nomenclature, and the data that support those repairs.

Comparison of the Suture Anchor and Transosseous Techniques for Patellar Tendon Repair: A Biomechanical Study

BACKGROUND

Minimizing gap formation and maximizing the strength of patellar tendon repairs are 2 critical factors for successful healing of these injuries.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare transosseous and screw-in anchor repair techniques to determine if there is a difference in gap formation and load to failure of the 2 constructs. The research hypotheses were that the anchor construct would have significantly less gap formation and would also have significantly greater load-to-failure strength.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 24 porcine specimens were randomly assigned into transosseous and 4.75-mm polyetheretherketone (PEEK) screw-in anchor repair groups. The repairs were then completed using 2 No. 2 FiberWire sutures, and each specimen was cyclically loaded on a tensile test machine to 250 N for a total of 1000 cycles. Gap formation was measured at 1, 10, 250, 500, and 1000 cycles. Each specimen was loaded to failure after 1000 cycles. Independent t tests were conducted.

RESULTS

Statistically significant gap formation and load-to-failure differences were found between the 2 repair techniques. The mean gap in the anchor group (2.16 ± 1.81 mm) was significantly less than that seen in the transosseous group (5.71 ± 1.58 mm) (P < .001). The mean load to failure of the anchor group (669.9 ± 91.8 N) was significantly higher than that of the transosseous group (582.8 ± 92.6 N) (P = .03).

CONCLUSION

The results support the 2 study hypotheses. These findings suggest that the 4.75-mm PEEK screw-in anchor construct may be superior to the transosseous technique for minimizing gap formation and improving load-to-failure strength after surgical repair of the patellar tendon.

CLINICAL RELEVANCE

The use of the suture anchor technique in patellar tendon repair may support early load-bearing rehabilitation.

Biomechanical evaluation of the Nice knot

Background:

The Nice knot is a bulky double-stranded knot. Biomechanical data supporting its use as well as the number of half hitches required to ensure knot security is lacking.

Materials and Methods:

Nice knots with, one, two, or three half-hitches were compared with the surgeon's and Tennessee slider knots with three half hitches. Each knot was tied 10 times around a fixed diameter using four different sutures: FiberWire (Arthrex, Naples, FL), Ultrabraid (Smith and Nephew, Andover, MA), Hi-Fi (ConMed Linvatec, Largo, FL) and Force Fiber (Teleflex Medical OEM, Gurnee, IL). Cyclic testing was performed for 10 min between 10N and 45N, resulting in approximately 1000 cycles. Displacement from an initial 10N load was recorded. Knots surviving cyclic testing were subjected to a load to failure test at a rate of 60 mm/min. Load at clinical failure: 3 mm slippage or opening of the suture loop was recorded. Bulk, mode of ultimate failure, opening of the loop past clinical failure, was also recorded.

Results:

During cyclic testing, the Nice knots with one or more half-hitches performed the best, slipping significantly less than the surgeon's and Tennessee Slider (P < 0.002). After one half-hitch, the addition of half-hitches did not significantly improve Nice knot performance during cyclic testing (P > 0.06). The addition of half-hitches improved the strength of the Nice knot during the force to failure test, however after two half-hitches, increase of strength was not significant (P = 0.59). While FiberWire was the most bulky of the sutures tested, it also performed the best, slipping the least.

Conclusion:

The Nice knot, especially using FiberWire, is biomechanically superior to the surgeon's and Tennessee slider knots. Two half hitches are recommended to ensure adequate knot security.

A Biomechanical Comparison of 3 Different Arthroscopic Lateral Ankle Stabilization Techniques in 36 Cadaveric Ankles

Arthroscopic lateral ankle stabilization has become an increasingly popular option among foot and ankle surgeons to address lateral ankle instability, because it combines a modified Broström-Gould procedure with the ability to address any intra-articular pathologic findings at the same session. The present study evaluated 3 different constructs in a cadaveric model. Thirty-six fresh frozen cadaver limbs were used, and the anterior talofibular ligament was identified and sectioned. The specimens were then placed into 1 of 3 groups. Group 1 received a repair with a single-row, 2-suture anchor construct; group 2 received repair with a novel, double-row, 4-anchor knotless construct; and group 3 received repair with a double-row, 3-anchor construct. Specimens were then tested for stiffness and load to ultimate failure using a customized jig. Stiffness was measured in each of the groups and was 12.10 ± 5.43 (range 5.50 to 22.24) N/mm for group 1, 13.40 ± 7.98 (range 6.71 to 36.28) N/mm for group 2, and 12.55 ± 4.00 (range 6.48 to 22.14) N/mm for group 3. No significant differences were found among the 3 groups in terms of stiffness (p = .939, 1-way analysis of variance, ɑ = 0.05). The groups were tested to failure, with observed force measurements of 156.43 ± 30.39 (range 83.69 to 192.00) N for group 1, 206.62 ± 55.62 (range 141.37 to 300.29) N for group 2, and 246.82 ± 82.37 (range 164.26 to 384.93) N for group 3. Statistically significant differences were noted between groups 1 and 3 (p = .006, 1-way analysis of variance, ɑ = 0.05). The results of the present study have shown that a previously reported arthroscopic lateral ankle stabilization procedure, when modified with an additional proximal suture anchor into the fibula, results in a statistically significant increase in strength in terms of the maximum load to failure. Additionally, we have described a previously unreported, knotless technique for arthroscopic lateral ankle stabilization.

Bone Staples Provide Favorable Primary Stability in Cortical Fixation of Tendon Grafts for Medial Collateral Ligament Reconstruction: A Biomechanical Study

Background:

The use of the interference screw (IFS) for the cortical fixation of tendon grafts in knee ligament reconstruction may lead to converging tunnels in the multiligament reconstruction setting. It is unknown whether alternative techniques using modern suture anchor (SA) or bone staple (BS) fixation provide sufficient primary stability.

Purpose:

To assess the primary stability of cortical fixation of tendon grafts for medial collateral ligament (MCL) reconstruction using modern SA and BS methods in comparison with IFS fixation.

Study Design:

Controlled laboratory study.

Methods:

Cortical tendon graft fixation was performed in a porcine knee model at the tibial insertion area of the MCL using 3 different techniques: IFS (n = 10), SA (n = 10), and BS (n = 10). Specimens were mounted in a materials testing machine, and cyclic loading for 1000 cycles at up to 100 N was applied to the tendon graft, followed by load-to-failure testing. Statistical analysis was performed using 1-way analysis of variance.

Results:

There were no statistical differences in elongation during cyclic loading or peak failure load during load-to-failure testing between BS (mean ± standard deviation: 3.4 ± 1.0 mm and 376 ± 120 N, respectively) and IFS fixation (3.9 ± 1.2 mm and 313 ± 99.5 N, respectively). SA fixation was found to have significantly more elongation during cyclic loading (6.4 ± 0.9 mm; P < .0001) compared with BS and IFS fixation and lower peak failure load during ultimate failure testing (228 ± 49.0 N; P < .01) compared with BS fixation.

Conclusion:

BS and IFS fixation provided comparable primary stability in the cortical fixation of tendon grafts in MCL reconstruction, whereas a single SA fixation led to increased elongation with physiologic loads. However, load to failure of all 3 fixation techniques exceeded the loads expected to occur in the native MCL.

Clinical Relevance:

The use of BS as a reliable alternative to IFS fixation for peripheral ligament reconstruction in knee surgery can help to avoid the conflict of converging tunnels.

Internal fixation of S1-S3 iliosacral screws and pubic screw as the best configuration for unstable pelvic fracture with unilateral vertical sacral fracture (AO type C1.3)

BACKGROUND

Although internal fixation is the definitive treatment in unstable pelvic fractures with disruption of the anterior arch and a vertical fracture of the sacrum (AO type C1.3), there have been no agreement of the best technique of internal fixation yet. We aimed to derive comparable objective data on stiffness and load to failure in this type of fracture fixations.

METHODS

Synbone was modified into AO type C1.3 fracture model, while treatments were divided into six internal fixation treatment groups using tension band plate (TBP), symphysis pubis plate (SP) with iliosacral screw at S1 and S2 (IS S1-S2), pubic screw (PS) with iliosacral TBP, PS and IS S1-S2, SP and IS S1-S3, PS and S1-S3 and finally PS and IS S1-S3. Sensor was applied to detect the shifting and rotation of fracture fragments. Mechanical strength test conducted with the application of axial force on the sacrum vertebra (S1).

RESULTS

The highest translational stiffness was observed in the group IS S1-S3 + PS (830.36 N/mm, p = 0.031) and there was no difference on the rigidity of the rotation between the groups posterior fixation using IS S1-S2 and IS S1-S3 ( p = 0.51). Meanwhile the highest load to failure was found in group IS S1-S3 + PS (1522.20 N). PS provided advantages compared to the use of plate.

CONCLUSIONS

Group of PS and S1-S3 IS is the configuration of internal fixation with best translational and rotational stiffness and the largest load to failure compared to other techniques in AO type C1.3 fracture.

Biomechanical evaluation of two arthroscopic techniques for biceps tenodesis: triple loop suture versus simple suture

BACKGROUND

Several techniques and procedures have been described to treat long head of the biceps pathology; however, tenodesis and tenotomy are the 2 most common procedures performed. This study evaluated the initial fixation strength of the biceps tenodesis triple loop suture (TLS) technique and compared it with that of the simple suture technique (SST).

METHODS

Twenty fresh frozen cadaveric human shoulders (humeral head and neck with attached biceps tendons) were harvested. The biceps tendon was tenotomized proximally before reattachment to the bicipital groove of the matching humerus using suture anchors. Tenodesis was performed using the SST or the TLS technique. Specimens were tested biomechanically for load to failure, stress, and stiffness. The mechanism of failure was evaluated and compared between the 2 suture techniques.

RESULTS

Maximal load to failure was significantly greater using the TLS technique (122.2 ± 26.73 N) than the SST (46.12 ± 14.37 N, P < .001). There was no difference in the mean stiffness (SST: 7.33 ± 4.41 N/mm, TLS: 7.46 N/mm ± 2.67, P = .94). The failure mechanism in all SST samples occurred by suture cutout through the longitudinal fibers of the tendon. In all TLS samples, the failure occurred by suture slippage.

CONCLUSION

This study demonstrated superior load to failure of the TLS compared with the SST technique for biceps tenodesis. Furthermore, this study provides the first description of the TLS technique as a possible application in biceps tenodesis. Clinical application of the TLS must be carefully considered, because although it achieved a superior biomechanical profile, experience with this stitch is limited.

Comparison of Suture-Based Anchors and Traditional Bioabsorbable Anchors in Foot and Ankle Surgery

We compared the pullout strength of a suture-based anchor versus a bioabsorbable anchor in the distal fibula and calcaneus and evaluated the relationship between bone mineral density and peak load to failure. Eight paired cadaveric specimens underwent a modified Broström procedure and Achilles tendon reattachment. The fibula and calcaneus in the paired specimens received either a suture-based anchor or a bioabsorbable suture anchor. The fibular and calcaneal specimens were loaded to failure, defined as a substantial decrease in the applied load or pullout from the bone. In the fibula, the peak load to failure was significantly greater with the suture-based versus the bioabsorbable anchors (133.3 ± 41.8 N versus 76.8 ± 35.3 N; p = .002). No significant difference in load with 5 mm of displacement was found between the 2 groups. In the calcaneus, no difference in the peak load to failure was found between the 2 groups, and the peak load to failure with 5 mm of displacement was significantly lower with the suture-based than with the bioabsorbable anchors (52.2 ± 9.8 N versus 75.9 ± 12.4 N; p = .003). Bone mineral density and peak load to failure were significantly correlated in the fibula with the suture-based anchor. An innovative suture-based anchor had a greater peak load to failure compared with a bioabsorbable anchor in the fibula. In the calcaneus, the load at 5 mm of displacement was significantly lower in the suture-based than in the bioabsorbable group. The correlation findings might indicate the need for a cortical bone shelf with the suture-based anchor. Suture-based anchors could be a viable alternative to bioabsorbable anchors for certain foot and ankle procedures.

The Biomechanical Stability of Bone Staples in Cortical Fixation of Tendon Grafts for Medial Collateral Ligament Reconstruction Depends on the Implant Design

BACKGROUND

The promising biomechanical stability of bone staples (BSs) in cortical fixation of tendon grafts for medial collateral ligament (MCL) reconstruction has been revealed by a previous investigation. However, it is currently unknown if the biomechanical stability of cortical fixation of tendon grafts depends on the BS design.

PURPOSE

To assess the biomechanical stability of cortical fixation of tendon grafts in knee surgery using 4 different BS designs.

STUDY DESIGN

Controlled laboratory study.

METHODS

Cortical fixation of tendon grafts was performed in a porcine knee model at the tibial insertion area of the MCL using 4 different BS designs (n = 40): 8-mm width without spikes (n = 10), 8-mm width with spikes (n = 10), 14-mm width with spikes (n = 10), and 13 mm-wide 4-prong staples with spikes (n = 10). Specimens were mounted in a materials testing machine, and cyclic loading was applied to the tendon graft (500 cycles at 50 and 100 N, respectively), followed by load-to-failure testing. The Kruskal-Wallis test was performed for statistical analysis (P < .05), and the post hoc Dunn test was performed for multiple comparisons.

RESULTS

In 4 of 10 specimens with graft fixation using BSs without spikes, slippage of the tendon underneath the BS led to failure of the construct during cyclic loading to 100 N. In the other groups, no fixation failure was observed during cyclic loading. Furthermore, graft fixation using BSs without spikes was found to have significantly more elongation during cyclic loading (8.2 ± 1.9 mm) and a lower ultimate failure load (170 ± 120 N) compared with graft fixation using narrow BSs with spikes (3.4 ± 1.2 mm [P < .0001] and 364 ± 85 N [P < .05], respectively) and graft fixation using broad BSs with spikes (4.5 ± 1.4 mm [P < .05] and 429 ± 67 N [P < .001], respectively). No statistical differences in elongation during cyclic loading or ultimate failure load were found between 4-prong staples with spikes (5.0 ± 1.3 mm and 304 ± 85 N) and narrow or broad staples with spikes.

CONCLUSION

The biomechanical stability of cortical fixation of an MCL graft was comparable between each BS design with spikes (narrow, broad, and 4-prong) in a porcine knee model, whereas BSs without spikes led to failure of the fixation construct during cyclic loading in 4 of 10 specimens and increased elongation and lower ultimate failure loads in the remainder of the group. BSs without spikes may therefore not be recommended for graft fixation.

CLINICAL RELEVANCE

The use of BSs can help to avoid the conflict of converging tunnels in multiligament reconstruction surgery. An implant design with spikes yields significantly higher biomechanical stability than BSs without spikes.

Biomechanical characteristics of subscapularis-sparing approach for anatomic total shoulder arthroplasty

BACKGROUND

A technique for retaining the superior 50% of the subscapularis insertion for anatomic total shoulder arthroplasty has been described. This cadaveric study biomechanically evaluates this subscapularis-sparing approach and compares it with a complete subscapularis release and repair technique to determine whether there is a higher load to failure.

MATERIALS AND METHODS

Twelve matched pairs of human cadaveric arms were distributed into 3 test groups. Group 1 consisted of specimens with and without a 100% subscapularis release. Group 2 consisted of specimens with and without an inferior 50% subscapularis release. Group 3 consisted of specimens with either an inferior 50% or 100% release of the subscapularis footprint and repair. All tendon repairs were performed using bone tunnels and sutures. Specimens were biomechanically tested using non-destructive cyclic and tensile failure-inducing loads.

RESULTS

In matched pairs, the following comparative results were obtained: native intact subscapularis specimens exhibited a load to failure of 1341.20 ± 380.10 N compared with 380.10 ± 138.79 N in the 100% release specimens (P = .029), native intact subscapularis specimens exhibited a load to failure of 1209.74 ± 342.18 N compared with 744.33 ± 211.77 N in the 50% release specimens (P = .057), and 50% release and repair specimens exhibited a load to failure of 704.62 ± 165.53 N compared with 305.52 ± 91.39 N in the 100% release and repair group (P = .029).

CONCLUSION

Preservation of the superior 50% of the subscapularis demonstrates a higher load to failure compared with complete subscapularis release and repair using bone tunnels.

Lumbar Intervertebral Spacer With Cement Augmentation of Endplates and Integrated Screws as a Fixation Device in an Osteoporotic Model: An In Vitro Kinematic and Load-to-Failure Study

BACKGROUND

Integrated lateral lumbar interbody fusion (LLIF) devices have been shown to successfully stabilize the spine and avoid complications related to posterior fixation. However, LLIF has increased subsidence risk in osteoporotic patients. Cement augmentation through cannulated pedicle screws enhances pedicle fixation and cage-endplate interface yet involves a posterior approach. Lateral application of cement with integrated LLIF fixation has been introduced and requires characterization. The present study set out to evaluate kinematic and load-to-failure properties of a novel cement augmentation technique with an integrated LLIF device, alone and with unilateral pedicle fixation, compared with bilateral pedicle screws and nonintegrated LLIF (BPS + S).

METHODS

Twelve specimens (L3-S1) underwent discectomy at L4-L5. Specimens were separated into 3 groups: (1) BPS + S; (2) polymethyl methacrylate (PMMA) augmentation, integrated LLIF, and unilateral pedicle screws (PMMA + UPS + iS); and (3) PMMA and integrated LLIF (PMMA + iSA) without posterior fixation. Flexion-extension, lateral bending, and axial rotation were applied. A compressive load was applied to L4-L5 segments until failure. An analysis was performed (P < .05).

RESULTS

Operative constructs significantly reduced motion relative to intact specimens in all motion planes (P < .05). BPS + S provided the most stability, reducing motion by 71.6%-86.4%, followed by PMMA + UPS + iS (68.1%-79.4%) and PMMA + iSA (62.9%-81.9%); no significant differences were found (P > .05). PMMA + UPS + iS provided the greatest resistance to failure (2290 N), followed by PMMA + iSA (1970 N) and BPS + S (1390 N); no significant differences were observed (P > .05).

CONCLUSIONS

Cement augmentation of vertebral endplates via the lateral approach with integrated LLIF moderately improved cage-endplate strength compared to BPS + S in an osteoporotic model; unilateral pedicle fixation further improved failure load. Reconstruction before and after application of unilateral pedicle screws and rods was biomechanically equivalent to anteroposterior reconstruction. Overall, initial results suggest that integrated LLIF with cement augmentation may be a viable alternative in the presence of osteoporosis.

Limited-Open Achilles Tendon Repair Using Locking Sutures Versus Nonlocking Sutures: An In Vitro Model

BACKGROUND

Several limited-open Achilles tendon repair techniques that use locking or nonlocking sutures have been developed, but direct comparisons of in vitro mechanical properties have not yet been reported in the literature. It was our hypothesis that loads applied to the repaired Achilles tendon would be better resisted by limited-open techniques that use locking stitches compared with limited-open repairs that use nonlocking stitches.

METHODS

The Achilles tendons of 31 fresh-frozen cadaver lower limbs were incised 4 cm proximal to the calcaneal insertion. Tendons were then repaired using 1 of 2 limited-open Achilles tendon repair tools, one using 3 nonlocking sutures and the other using a combination of locking and nonlocking sutures. Repaired specimens were cycled to 1000 cycles from 20 to 100 N and from 20 to 190 N followed by a single load to failure test. Nonparametric analyses were performed to compare the number of cycles to gapping and total load to failure between the 2 repair techniques.

RESULTS

During cyclic loading, more cycles occurred prior to detection of 2-mm and 9.5-mm gaps in the locking suture construct compared with the nonlocking suture construct ( P = .012 and P = .005, respectively). There was no difference in the number of cycles to a gap of 5 mm ( P = .053). The locking suture construct also resisted a significantly greater load to failure compared with the nonlocking suture construct ( P < .001; median 385.0 and 299.6 N, respectively).

CONCLUSION

Limited-open repair techniques using locking sutures provided greater construct strength under both cyclic and ultimate loads compared with a repair technique that used only nonlocking sutures.

CLINICAL RELEVANCE

Limited-open Achilles tendon repairs using locking sutures are better able to resist forces simulating early accelerated rehabilitation than repairs using nonlocking sutures.

Titanium Cable Cerclage Increases the Load to Failure in Plate Osteosynthesis for Distal Femoral Fractures

Background and Objectives: The reduction of two-part oblique or spiral fractures of the distal femur using steel wire cerclage prior to plate osteosynthesis is a proven procedure. In addition to being useful in fracture reduction, wire cerclage was also shown to increase the stability of osteosynthesis. Nevertheless, metal corrosion and the allergenic potency of steel remain problematic disadvantages of this method. A biomechanical study was carried out to evaluate titanium cable cerclage as an alternative supplement for plate osteosynthesis of a distal femoral two-part fracture. Materials and Methods: An unstable AO/OTA 32-A2.3 fracture was created in eleven pairs of nonosteoporotic human cadaver femora. All the samples were treated with polyaxial angular stable plate osteosynthesis. One femur from each pair was randomly selected for an additional fracture fixation with multifilament titanium cable cerclage. Stepwise cyclic axial loading was applied in a load-to-failure mode using a servohydraulic testing machine. Results: All specimens (mean age: 80 years; range: 57-91 years) withstood a cycling force of at least 1800 N. With a mean load of 2982 N (95% CI: 2629-3335 N), the pressure forces resulting in osteosynthesis failure were significantly higher in specimens with an additional titanium cerclage (Group 1) than in samples that were solely treated with plate osteosynthesis (Group 2) at 2545 N (95% CI: 2257-2834 N) (p = 0.024). In both groups, cutting out the distal screws at the condyle region, resulting in shearing of the distal fragment proximal to the fracture line, was the most frequent cause of construct failure. Among the specimens assigned to Group 1, 36% exhibited a specific fracture pattern, namely, a fracture of the dorsal buttress above the cerclage. Analysis of axial stiffness (p = 0.286) and irreversible deformity of the specimens revealed no differences between the groups (p = 0.374). Conclusion: Titanium cable cerclage application, as a supplement to an angular stable plate, resulted in an increased load to failure. In terms of stability, the use of this adjunct for fracture fixation of supracondylar two-part oblique femoral fractures might, therefore, be an option, especially in patients who are sensitive to nickel.

Biomechanical Comparison of FiberLock Suspensionplasty and Flexor Carpi Radialis Ligament Reconstruction for Treatment of Thumb Carpometacarpal Osteoarthritis

BACKGROUND

The purpose of this study was to compare the cyclic and load to failure characteristics of post-trapeziectomy suspensionplasty with the FiberLock Suspension System (FLSS; Arthrex Inc., Naples, Florida) to flexor carpi radialis ligament reconstruction (FCRLR). We hypothesized that the FLSS will have increased stiffness, yield, and ultimate load compared with FCRLR.

METHODS

Ten matched pairs of cadaveric hands were used. One side of each pair was randomly assigned to receive the FCRLR or FLSS and the contralateral side received the other suspensionplasty. A complete trapeziectomy was performed followed by FLSS or FCRLR. Cyclic and load to failure characteristics were measured with loading in the distal to proximal direction. A preload of 1 N with 30 cycles of 1 N to 10 N was applied, followed by load to failure. A paired t test was used for statistical analysis (P < .05).

RESULTS

The FLSS had significantly decreased nonrecoverable deformation and deformation at peak load during cyclic loading (P < .04). The FLSS also had significantly increased stiffness, yield load, ultimate load, and load and energy absorbed at 10 mm displacement compared with FCRLR (P < .04). All 10 FCRLR specimens failed with suture tearing through the tendon. Nine FLSS specimens failed due to suture slipping from the SwiveLock anchor (Arthrex Inc., Naples, Florida) and 1 failed due to the FiberTak anchor (Arthrex Inc., Naples, Florida) pulling through the index metacarpal.

CONCLUSION

Suspensionplasty with the FLSS demonstrated greater structural integrity compared with FCRLR following trapeziectomy. The FLSS procedure may result in decreased thumb subsidence and decreased construct failure.

The effect of ethanol on rotator cuff repairs in a rodent model

BACKGROUND

Alcohol consumption is a significant risk factor for both the occurrence and severity of rotator cuff tears. However, there is limited supporting evidence to suggest that alcohol use is associated with suboptimal outcomes after operative repair of rotator cuff tears. Rat shoulders have been demonstrated as consistent and reliable models for studying rotator cuff disease. Perioperative alcohol exposure will negatively impact the biomechanical and histologic properties of surgically repaired rotator cuffs in rats.

METHODS

Rats were randomized to receive a 20% ethanol or isocaloric control solution as their primary source of drinking water. A tenotomy of the supraspinatus tendon from bone was performed surgically and then immediately repaired with a transosseous technique. After surgery, rats were continued on the same exposure solution until animals were humanely euthanized at 7, 14, or 21 days postoperatively. The surgically repaired shoulders underwent biomechanical testing to assess load to failure and failure strain. The histologic evaluation of tendon-to-bone healing was performed by a blinded pathologist using a qualitative grading system. Quantitative reverse transcription-polymerase chain reaction on total RNA from tendon-to-bone interface tissue was performed to quantify the mRNA expression of type I and III collagen, and transforming growth factor-β 1 (TGF-β 1) and 3 (TGF-β 3) at the repair site.

RESULTS

Biomechanical testing showed that repaired shoulder constructs in rats exposed to ethanol had significantly lower load to failure at 7 days postoperatively relative to repairs in rats exposed to a control solution. No other biomechanical parameters or time points reached statistical significance. TGF-β3 mRNA expression was found in significantly higher quantities at the repair sites of rats exposed to ethanol at 7 days postoperatively relative to control rat repair sites. No other time points or factors reached statistical significance. No significant differences were identified among time points or groups at the healing tendon-to-bone interface.

CONCLUSIONS

Alcohol exposure significantly decreases biomechanical load to failure of rotator cuff repairs in the early postoperative period in rat models. In the later postoperative period, alcohol exposure was not associated with a decrease in biomechanical load to failure compared with controls. In addition, rats exposed to ethanol have significantly higher TGF-β3 expression at repair sites on postoperative day 7. These data suggest that ethanol consumption does deleteriously affect rotator cuff and bone healing. Future study is needed to validate the clinical significance of these findings in humans.

Comparison of Mechanical Properties of Non-ridged Versus Ridged Backslabs in Lower Limb Fractures

Introduction Lower limb fractures frequently require immobilization with backslabs to promote healing. This study investigates a novel approach involving the incorporation of a single ridge to enhance backslab strength while maintaining cost-effectiveness. Objective The aim of this study was to assess the mechanical performance of ridged backslabs in comparison to traditional non-ridged backslabs, specifically focusing on their load-bearing capacity and cost-effectiveness when used in lower limb fractures. Methods This experimental study, conducted between January 2023 and June 2023, compares three groups of backslabs with varying layers (eight, ten, and twelve) that were fabricated, each consisting of four ridged and four non-ridged specimens. These backslabs, constructed from six-inch plaster of Paris rolls, were 190 cm in length. A three-point bending test was conducted on both groups using a Hounsfield H100KS Universal Testing Machine (Tinius Olsen Ltd., Redhill, UK), with a crosshead speed of 5 mm/min and a span distance of 190 mm between supports. Results Significant differences in mean maximum force endured were observed between the ten-layered and twelve-layered flat and ridged backslabs (p-values: 0.003 and 0.004, respectively). Ten-layered ridged backslabs exhibited a 56 N higher load-bearing capacity, while twelve-layered ridged backslabs withstood 73.9 N more force than their flat counterparts, underscoring the superior strength of ridged lower limb backslabs. Conclusion Ridged backslabs outperformed non-ridged backslabs in terms of strength when subjected to external forces. These findings support the potential adoption of ridged backslabs as a lightweight, cost-effective, and robust alternative for immobilization in lower limb fractures.

Tensile testing in feline ventral abdominal coeliotomy closure with different sizes of polydioxanone suture material: a biomechanical study

OBJECTIVES

The aim of this study was to evaluate, in vitro, the load and type of failure of the sutured ventral abdominal fascia of cats with different sizes of suture material made of polydioxanone (PDX) (2-0, 3-0, 4-0, 5-0 USP).

METHODS

A total of 32 samples of the ventral abdominal wall from 16 cadaveric cats were harvested using an hourglass-shaped template. The samples were sectioned longitudinally along the linea alba and then sutured together in a continuous pattern using four different randomly assigned sizes of pdx suture material (2-0, 3-0, 4-0, 5-0 USP). A universal testing machine was used for linear distraction of the samples. The tensile strength and type of failure were recorded and analysed. Three types of failure were defined: suture material failure (S), suture line failure (T1) and failure of the abdominal wall further away from the linea alba (T2).

RESULTS

The frequency of suture material failure decreased with increasing suture size. Suture size 5-0 failed due to a S failure in 6/8 samples, PDX 4-0 failed in 2/8 samples and PDX 3-0 failed in only 1/8 samples. However, PDX 2-0 failed due to only T1 or T2 failures, with both failures being almost equally represented. No statistically significant differences in the load to failure between PDX 2-0, 3-0 and 4-0 were noted (P >0.05). The risk of suture failure increased with decreasing suture size diameter.

CONCLUSIONS AND RELEVANCE

PDX 2-0 and 3-0 can be used without reservation for the closure of ventral midline coeliotomy in cats. Although there was no statistically significant difference between PDX 2-0, 3-0 and 4-0, PDX 4-0 showed a higher probability for suture breakage and should be used only after careful consideration of the patient while clinical evaluation is pending. Pdx 5-0 cannot be recommended as a safe suture size for this type of surgical closure.

The effect of the central post and screw constructs on the Univers Revers Total Shoulder System

BACKGROUND

The use of lateralized glenoid components in reverse total shoulder arthroplasty is increasing to avoid scapular notching and improve strength and impingement-free range of motion. However, maximizing glenoid lateralization increases stress at the bone-baseplate interface. The ideal type and length of central fixation remains a subject of debate. The purpose of this study was to compare baseplate micromotion and load to failure in a biomechanical model with either a central or post for fixation of a reverse total shoulder arthroplasty baseplate. The primary hypothesis was that bicortical post or screw placement would improve baseplate stability compared with fixation contained within the vault. Secondary hypotheses were that larger amounts of construct lateralization would increase micromotion and decrease baseplate stability, regardless of the central fixation method.

METHODS

Based on previously published work with similar methods and reported measures, a power analysis determined an adequate sample size of n = 6 for statistical comparisons between 6 groups, with an α of 0.05 and a power of 0.8. Thirty-six shoulder scapulae (12 pcf Sawbones; Pacific Research Laboratories) were implanted with a nonaugmented baseplate, glenosphere, and 4 peripheral screws as well as either a central screw or post. The post groups were either contained within the glenoid or penetrated the vault (bicortical). All groups with a central screw were bicortical. Lateralization was tested at both 4 mm and 8 mm. All implants (Univers Revers Total Shoulder System; Arthrex Inc., Naples, FL, USA) were placed using a glenoid-specific guide for optimal and consistent positioning of the central guide pin and confirmed by both X-ray and computed tomography analysis. Cyclic testing was performed with increasing load until baseplate micromotion exceeded 150 μm. Load to failure testing was performed with failure defined as a baseplate displacement of 1000 μm or scapula fracture. Analysis of variance testing was performed to evaluate for statistical significance between groups (P < .05).

RESULTS

There was no difference in micromotion testing in all 6 groups (P = .390). Lateralization at 4 mm or 8 mm did not significantly affect micromotion testing. Test groups with 4 mm of lateralization and a central post contained within the vault (P = .01) and 4 mm of lateralization with a central bicortical screw (P = .005) had statistically significantly greater load to failure than the other groups.

CONCLUSIONS

With a nonaugmented glenoid baseplate and 4-8 mm of lateralization, central posts within the vault, central posts exiting the vault, and bicortical screw fixation were equivocal in terms of micromotion. Load to failure was highest with 4 mm of lateralization and a central post contained within the glenoid vault or a bicortical screw. With 8 mm of lateralization and the use of 4 peripheral screws, there is no difference between a central post exiting the vault, post within the vault, and bicortical screw fixation.