Mechanical evaluation of a soft tissue interference screw with a small diameter: significance of graft/bone tunnel cross-sectional area ratio

Modified Broström-Gould With Gracilis Autograft Augmentation Surgery and Accelerated Noncasted Rehabilitation in High Demand Patients With Lateral Ankle Instability

Lateral ankle instability that has failed conservative management can be physically debilitating. Good outcomes are obtained from Broström-Gould augmented repair techniques, however there are few studies evaluating the use of a gracilis autograft augmentation coupled with an accelerated rehabilitation program in high functional demand patients. We believe that the modified Broström-Gould technique utilizing a Gracilis autograft will provide significant improvements in stability while maintaining normal ankle biomechanics in young, high demand patients. The prospective cohort study involved 19 patients (20 ankles) who underwent surgery for chronic lateral ankle instability by a single surgeon, at a single institution between October 2014 and April 2016. Patients were followed for 33.8 ± 11.7 (range 12-48) months. Patients were assessed both pre- and postoperatively for talar tilt angle radiographically and with both American Orthopaedic Foot and Ankle Society Ankle and Hindfoot scores and Karlsson-Peterson scores. A Tegner activity score was taken at the last follow-up. The mean American Orthopaedic Foot and Ankle Society score increased from 68.85 ± 10.57 to 91.56 ± 5.31 points (p < .01) and mean Karlsson-Peterson score increased from 50.9 ± 15.53 to 88.11 ± 8.64 points (p value <.01) when compared preoperatively to mean postoperative follow-up of 33.8 months. Tegner activity score was 7.05 ± 0.89 at last follow-up. The technique was found to be effective in treating chronic lateral ankle instability and in combination with an accelerated rehabilitation protocol, patients returned to their premorbid level of activity with improved stability and no significant effect on donor graft site morbidity.

Screw oversizing for anterior cruciate ligament graft fixation in primary and enlarged tibial tunnels: A biomechanical study in a porcine model

BACKGROUND

Ideal diameter for tibial interference screw fixation of the anterior cruciate ligament (ACL) graft remains controversial. Tibial graft fixation with screws matching the tunnel diameter vs. one-millimetre oversized screws were compared.

METHODS

In 32 cadaveric porcine tibiae, bovine extensor tendons with a diameter of eight millimetres were fixed in (I) a primary ACL reconstruction scenario with eight-millimetre tibial tunnels (pACL), with eight-millimetre (pACL-8) vs. nine-millimetre (pACL-9) screws, and (II) a revision ACL reconstruction scenario with enlarged tunnels of 10 mm (rACL), with 10-mm (rACL-10) vs. 11-mm (rACL-11) screws. Specimens underwent cyclic loading with low and high load magnitudes followed by a load-to-failure test. Graft slippage and ultimate failure load were recorded.

RESULTS

In comparison with matched-sized screws (pACL-8), fixation with oversized screws (pACL-9) showed with significantly increased graft slippage during cyclic loading at higher load magnitudes (1.19 ± 0.23 vs. 1.98 ± 0.67 mm; P = 0.007). There were no significant differences between the two screw sizes in the revision scenario (rACL-10 vs. rACL-11; P = 0.38). Graft fixation in the revision scenario resulted in significantly increased graft slippage in comparison with fixation in primary tunnels at higher loads (pACL vs. rACL; P = 0.004). Pull-out strengths were comparable for both scenarios and all screw sizes (P > 0.316).

CONCLUSIONS

Matched-sized interference screws provided better ACL graft fixation in comparison with an oversized screw diameter. In revision cases, the fixation strength of interference screws in enlarged tunnels was inferior to the fixation strength in primary tunnels.

Anatomic medial patellofemoral ligament reconstruction using patellar suture anchor fixation for recurrent patellar instability

PURPOSE

The purpose of this study was to prospectively evaluate clinical and radiographic outcomes following anatomic medial patellofemoral ligament (MPFL) reconstruction using patellar suture anchor fixation for recurrent patellar instability.

METHODS

Twenty patients (20 knees) were enrolled in this study. The median age was 21 years, and the median follow-up was 34.5 months. Reconstruction was performed using a hamstring autograft fixed with two suture anchors at native patellar site of the MPFL. No patient had undergone additional medial tibial tuberosity transfer. Clinical scores (Kujala, Lysholm, and Tegner score) and apprehension test were completed preoperatively and at the follow-up. Preoperative and follow-up radiographic assessments included modified Insall-Salvati ratio, congruence angle, and lateral patellofemoral angle.

RESULTS

The preoperative Kujala and Lysholm scores were 52.6±12.4 and 49.2±10.7, and at follow-up visits, corresponding values were 90.9±4.5 (p<0.001) and 90.9±5.2 (p<0.001). Tegner score increased from 3.0 (range 1-4) to 5.0 (range 4-7) (p<0.001). The apprehension test was positive in all patients preoperatively, but only positive in one patient at follow-up. All radiographic assessments were significantly improved; modified Insall-Salvati index (from 1.75 to 1.65) (p=0.002), congruence angle (from 6.3° to -7.0°) (p<0.001), and lateral patellofemoral angle (from 2.1° to 4.9°) (p=0.008). No patient experienced a patellar fracture or redislocation.

CONCLUSION

These results are comparable to those of bone tunnel techniques reported in the literature. This study shows that anatomic MPFL reconstruction using two suture anchors is a reliable treatment option.

LEVEL OF EVIDENCE

Case series with no comparison group, Level IV.

Comparison of outside-in and inside-out technique for tibial fixation of a soft-tissue graft in ACL reconstruction using the Shim technique

INTRODUCTION

The aim of this study was to compare the biomechanical properties of tibial fixation of a free tendon graft in ACL reconstruction using the Shim, a new wedge-shaped implant, in an outside-in technique to fixation by the Shim used in an inside-out technique and fixation by interference screw in a porcine model.

MATERIALS AND METHODS

Porcine tibia and flexor tendons were used. In Group 1, the Shim was applied outside-in. In Group 2, the Shim was inserted inside-out. In the Group 3, an 8-mm interference screw was used. Ten specimens were tested in each group. Load-to-failure, elongation, stiffness and failure mode were recorded. Cyclic loading was performed between 5 and 250 N for 1,000 cycles, followed by a load to failure testing.

RESULTS

Mean maximum load-to-failure was 629.53 N in Group 1,648.54 N in Group 2 and 749.53 N in Group 3. There was no significant difference between the groups. Stiffness varied between 127.34 N/mm in Group 1, 151.27 N/mm in Group 2 and 182.25 N/mm in Group 3. No significant differences were found between outside-in Shim and interference screw fixation. No significant difference was found for elongation among the three groups. The main failure mode was a rupture of the tendon in the IFS group and a slippage of either the implant or the tendon in both groups using the Shim.

CONCLUSIONS

As no statistically significant difference could be seen concerning load to failure, stiffness and elongation between the inside-out and the outside-in techniques, the Shim can be used for tibial fixation in an outside-in or inside-out technique depending on the preference of the surgeon. To prevent slippage of the graft a hybrid fixation should be considered.

Accelerated Versus Traditional Rehabilitation After Anterior Talofibular Ligament Reconstruction for Chronic Lateral Instability of the Ankle in Athletes

BACKGROUND

Although several reconstruction procedures for chronic lateral ankle instability using autografts have been reported, all have recommended postoperative immobilization and a nonweightbearing period.

HYPOTHESIS

Reconstructive surgery with a gracilis autograft using an interference fit anchoring system for chronic lateral ankle instability enables early accelerated rehabilitation and recovery with a return to activity without requiring immobilization.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 33 patients (33 feet) who underwent reconstruction of the anterior talofibular ligament with a gracilis autograft using interference screws were included; 15 were followed for 4 weeks with postoperative cast immobilization (group I), while 18 were followed with accelerated rehabilitation without immobilization (group A). Clinical and radiological results were evaluated based on the Karlsson and Peterson score, talar tilt angle, anterior displacement of the talus on stress radiography, and time between surgery and return to full athletic activity.

RESULTS

The mean Karlsson and Peterson scores before and 2 years after surgery were the following: for group I: 62.3 ± 4.7 (range, 54-72) and 94.4 ± 7.1 (range, 76-100), respectively (P < .001), and for group A: 64.1 ± 4.8 (range, 57-70) and 91.7 ± 7.7 (range, 74-100), respectively (P < .001). The mean difference in the talar tilt angle compared with the contralateral side and mean displacement of the talus on stress radiography before and 2 years after surgery were the following: for group I: 8.7° ± 2.6° and 7.7 ± 1.8 mm and 3.8° ± 1.5° and 4.0 ± 1.6 mm, respectively, and for group A: 10.5° ± 3.4° and 8.7 ± 2.1 mm and 4.3° ± 1.8° and 4.3 ± 1.2 mm, respectively. Radiography revealed significantly improved postoperative outcomes in both groups (P < .0001). No significant differences in the score and any parameters on stress radiography were evident at 2 years after surgery between the groups. The mean time between surgery and return to full athletic activity was significantly higher in group I (18.5 ± 3.5 weeks) than in group A (13.4 ± 2.2 weeks) (P < .0001). No cases of reinjury were reported, and no differences in athletic performance ability were observed between the groups.

CONCLUSION

Patients in group A returned to full athletic activity 5 weeks earlier than those in group I, demonstrating the advantage of accelerated rehabilitation after surgery.

Current trends in anterior cruciate ligament reconstruction

The advances in the knowledge of anatomy, surgical techniques, and fixation devices have led to the improvement of anterior cruciate ligament (ACL) reconstruction over the past 10 years. Nowadays, double bundle and anatomical single bundle ACL reconstruction that more closely restores the normal anatomy of the ACL are becoming popular. Although there is still no definite conclusion whether double bundle ACL reconstruction provides better clinical results than single bundle reconstruction, the trend has shifted to anatomic reconstruction regardless of single bundle or double bundle techniques. We could not find any significant differences in the clinical outcomes and stability after ACL reconstruction according to the type of graft or fixation device. Therefore, surgeons should select an ideal ACL reconstruction according to the patient's condition and surgeon's experience.

Medial patellofemoral ligament reconstruction: fixation strength of 5 different techniques for graft fixation at the patella

PURPOSE

To compare the structural properties of 5 different fixation strategies for a free tendon graft at the patella in medial patellofemoral ligament (MPFL) reconstruction under cyclic loading and load to failure testing.

METHODS

We used porcine patella and flexor tendons. We tested the following fixation techniques: 3.5-mm titanium anchor, transosseous 1-mm braided polyester suture, interference screw fixation, medial bone bridge, and transpatellar tunnels. We preconditioned each graft between 5 and 20 Nm before cyclic loading with 100 Nm for 1,000 cycles was started, and then performed load to failure testing. We recorded maximum load, stiffness, and elongation.

RESULTS

In the bone bridge group, 60% of all specimens failed during cyclic testing. Fixation by transosseous sutures showed significantly less stiffness compared with all other techniques (P < .05). The bone bridge technique showed significantly lower load to failure compared with all other techniques (P < .05). Differences between the other groups were not significant.

CONCLUSIONS

Fixation of a free tendon graft by transosseous sutures provides similar load to failure and elongation but less stiffness compared with fixation by anchors, interference screws, or transverse tunnels. Load to failure for the bone bridge technique was significantly lower than that for all other techniques. Furthermore, this fixation technique had a lower load to failure than that of the native MPFL.

CLINICAL RELEVANCE

Fixation of soft tissue grafts at the patella by 1-mm braided polyester suture provides adequate fixation strength without implants in the patella, which might cause soft tissue irritation. Further studies will have to show if the lesser stiffness of this technique causes problems in the clinical setting or if this laxity might even be an advantage because it makes this reconstruction more forgiving concerning overtensioning the graft. Significantly lower load to failure of the bone bridge technique should be considered in postoperative treatment.

Tendon graft--ulna fixation in distal radio-ulnar joint stabilisation; biomechanical comparison of three graft-bone fixation methods

A common distal radio-ulnar joint (DRUJ) stabilisation procedure uses a tendon graft running from the lip of the radial sigmoid notch to the ulnar fovea and through a bony tunnel to the ulnar shaft, before being wrapped round the distal ulna and sutured to itself. Such graft fixation can be challenging and requires a considerable tendon length. The graft length could be reduced by fixing the graft to the ulna using a bone anchor or interference screw. The aim of this study was to compare the strength of three distal ulna graft fixation methods (tendon wrapping and suturing, bone anchor and interference screw). Four human cadaveric ulnae were used. A tendon strip was run through a tunnel in the distal ulna and secured by: (1) wrapping round the shaft and suturing it to itself, (2) a bone anchor and (3) an interference screw in the bone tunnel. Load to failure was determined using a custom-made apparatus and an Instron machine. Maximum failure load was highest for the bone anchor fixation (99.3 +/- 23.7 N) followed by the suturing (96.2 +/- 12.1 N), and the interference screw fixation (46.9 +/- 5.6 N). There was no significant difference between the tendon suturing and bone anchor methods, but the tendon suturing was statistically significantly higher compared to the interference screw (P = 0.028). In performing anatomical stabilisation of the DRUJ fixation of the tendon graft to the distal ulna with a bone anchor provides the most secure fixation. This may make the stabilisation technique less demanding and require a smaller tendon graft.