Effect of suturing the femoral portion of a four-strand graft during an ACL reconstruction

Purpose

A suture passed along the part of the graft that will be inserted into the femoral tunnel is widely used by surgeons, because it could prevent the graft sliding on the femoral fixation device during pulling from the tibial side. The aim of this study was to evaluate the biomechanical effects of suturing the intratunnel femoral part of the graft during an anterior cruciate ligament (ACL) reconstruction.

Methods

Bovine digital extensor tendons and tibias were harvested from 20 fresh-frozen mature bovine knees ranging in age from 18 to 24 months. Quadruple-strand bovine tendons were passed through the tibial tunnel and secured distally with a bioabsorbable interference screw. In one half of all grafts (N = 10), the looped-over part of the graft was sutured in a whipstitch technique over a distance of 30 mm (Group 1). In one half of all grafts (N = 10), the looped-over part was left free from any suture (Group 2). The grafts were preconditioned at 50 N for 10 min, followed by cyclic loading at 1 Hz between 50 N and 250 N for 1,000 cycles. Load-to-failure test was then carried out at a rate of 1 mm/s.

Results

There was no statistically significant difference between mean stiffness at pullout and yield load between the two groups. In all specimens on Group 1, failure occurred following to partial breaking and then slipping of the tendons between the screw and the tunnel. Concerning Group 2, in six cases failure occurred as described for Group 1 specimens. In the remaining four cases, failure occurred entirely through the ligament mid-substance.

Conclusions

Suturing in a whipstitch fashion the femoral portion of the graft doesn’t affect the mechanical proprieties of the ACL graft. When suspension fixation device is used, suturing the looped-over part of the graft could be helpful in order to provide equal tension in all of the strands of the graft at time of tibial fixation.     

Biomechanical and viscoelastic properties of different posterior meniscal root fixation techniques

Purpose

The purpose of the present study was to biomechanically compare three different posterior meniscal root repair techniques. Transtibial fixation of a posterior meniscus root tear (PMRT) combined with an anterior cruciate ligament (ACL) reconstruction via one tunnel only shows similar properties in terms of cyclic loading and load to failure compared with direct anchor fixation.

Methods

Twenty-eight porcine knees were randomly assigned to 4 groups (n = 7 each): (1) native posterior meniscal root, (2) suture anchor repair, (3) refixation via a tibial ACL tunnel in combination with an interference screw fixation of the ACL graft, and (4) refixation via a tibial ACL tunnel in combination with an interference screw fixation of the ACL graft with an additional extracortical button fixation. The four groups underwent cyclic loading followed by a load-to-failure testing. Construct elongation during 1000 cycles, dynamic stiffness, attenuation, maximum force during load-to-failure testing, and failure mode were recorded.

Results

All reconstructions showed a significant lower maximum load (p < 0.0001) compared with the native meniscal root. The elongation for the transtibial fixation via the ACL tunnel without an additional extracortical backup fixation was significantly higher compared with the suture anchor technique (p < 0.0001). The additional use of a backup fixation led to similar results compared with the anchor repair technique.

Conclusion

The transtibial refixation of the meniscal root can be combined with an ACL reconstruction using the same tibial bone tunnel. However, an additional extracortical backup fixation is necessary. This might avoid a slippage of suture material and a failure of meniscus root fixation.

     

Interference screws should be shorter than the hamstring tendon graft in the bone tunnel for best fixation

Purpose

Interference screw fixation of hamstring tendon grafts in bone has to overcome the challenges that tendons have a slippery surface and viscoelastically adapt under pressure. As the typical failure mode of the graft is to slip past the interference screw, it was hypothesized that the position and configuration of the graft end may be of influence on the fixation strength.

Methods

Different configurations of the graft ending and its effect to primary fixation with interference screws after viscoelastic adaptation were tested in six groups: I: graft and the screw inserted at the same depth, II/III: the graft overlaps the tip of the screw (interference screw of 28 and 19 mm in length, respectively), IV: strengthening of the graft ending with additional suture knots, V: Endopearl, respectively, and VI: effect of partial retraction of the screw after excessive insertion. In vitro tests were performed with fresh calf tendon grafts and interference screws in bone tunnels (fresh porcine distal femur) all of 8 mm in diameter.

Results

The relative position of the graft ending to the tip of the interference screw thereby was recognized as a significant factor on pullout forces. Further strengthening at the graft endings with additional suture knots or an Endopearl device could improve primary hold as well.

Conclusions

Better fixation strength is achieved if the tip of interference screw does not extend past the end of a tendon graft. Enforcement of the tendon end with sutures or an implant can further improve fixation.     

Bioabsorbable interference screw versus bioabsorbable cross pins: influence of femoral graft fixation on the clinical outcome after ACL reconstruction

Purpose

The aim of this study was to evaluate the clinical outcome and differences in anterior–posterior laxity of ACL reconstruction using a bioabsorbable interference screw for femoral graft fixation when compared to femoral bioabsorbable cross pin fixation.

Methods

Clinical outcome was evaluated among 59 patients 1?year after arthroscopic ACL reconstruction with hamstrings graft in a prospective, non-randomised study. In 31 cases, femoral fixation of the graft was performed using a bioabsorbable interference screw. In 28 cases, two bioabsorbable cross pins were used for femoral fixation. Patients were evaluated using Tegner, Lysholm and Marshall scores, the visual analogue scale for pain and KT-1000 arthrometer measurement.

Results

No significant difference (P?≥?0.05) was observed at follow-up for the knee scores. The average Tegner score was 5.83 points (±2.00) for the interference screw fixation and 5.83 points (±1.24) for the cross pin fixation; the average Lysholm score was 93.58 (±5.79) to 92.72 (±6.34) points; and the average Marshall score 46.72 (±2.4) to 47.30 (±2.35) points. No significant difference was found for the visual analogue scale for pain. KT-1000 arthrometer measurement revealed a significant (P?<?0.05) difference in the mean side-to-side anterior translation at all applied forces. At 67?N, the mean difference was 1.53?mm (±1.24) in the interference screw group and 0.47?mm (±1.18) in the cross pin group (P?<?0.05). At 89?N, the mean differences were 1.85?mm (±1.29) versus 0.59?mm (±1.59), respectively, (P?<?0.05), and maximum manual displacements were 2.02?mm (±1.26) versus 1.22?mm (1.18; P?<?0.05).

Conclusions

In ACL reconstruction with hamstrings graft, similar clinical results are obtained for the use of bioabsorbable cross pins when compared to bioabsorbable interference screws for femoral fixation. Cross pin fixation was superior with regard to the anteroposterior laxity as measured with KT-1000.     

Migration of “bioabsorbable” screws in ACL repair. How much do we know? A systematic review

Purpose

Although bioabsorbable screws promise to degrade within months up to several years after implantation, often this does not happen. In fact, other problems such as screw breakage, tunnel enlargement, allergic or foreign body reactions, cyst or abscess formation, and delayed migration of “biodegradable” screws have been reported. This study aims to provide relevant basic science knowledge and recent insights concerning “biomaterials” currently used in fixation devices for anterior cruciate ligament (ACL) repair. A systematic review on the topic of screw “migration” is provided.

Methods

A PubMed search combining all the key terms was done looking for complications related to late migration of “bioabsorbable” screws used in ACL reconstruction without inferior time limitation up to January 2012. Only clinical reports were included. Reference lists of reports were checked to detect others not identified by the original search. A pre-publication search was performed to identify the most recent relevant articles.

Results

A total of ten articles referred to migration of “bioabsorbable” interference screws. Most cases reported on poly-L-lactic acid-based screws. Migration was noticed between 3 and 22 months postoperatively. It was noticed both in the tibia and the femur and with the application of several types of graft.

Conclusion

Migration is a possible complication of “bioabsorbable” interference screws. The information related to all clinical implications of the so-called “biodegradable screws” remains scarce and probably suffers from the phenomenon of publication bias. The complexity of possible reactions occurring in the human body is difficult to reproduce under controlled laboratory conditions.

Level of evidence

Systematic review including case-reports, Level V.     

Surgical management of osteochondritis dissecans of the knee in the paediatric population: a systematic review addressing surgical techniques

Purpose

Several case series have been published exploring a variety of surgical treatments for osteochondritis dissecans (OCD) in patients 18 years and younger, but a systematic review is currently lacking. This systemic review identifies the various surgical techniques reported in the literature for treating OCD and assesses the effectiveness of these treatments based on functional outcomes and radiographic healing.

Methods

A search of the EMBASE and MEDLINE databases was performed to identify clinical studies reporting outcomes of surgical management of OCD in the knee. A quality assessment of the included articles was conducted independently by 2 reviewers using a quality assessment tool developed by Yang et al.

Results

A total of 25 papers including 470 patients aged ≤18 years (516 lesions) met the eligibility criteria and were reviewed. Surgical techniques for stable lesions included (arthroscopic and open) transarticular drilling, either alone (41 %) or with bioabsorbable pin fixation (3 %), extra-articular drilling (29 %) and fixation with bioabsorbable screws (4 %) or bone pegs (4 %). For unstable lesions, surgical techniques included (arthroscopic and open) fixation with bioabsorbable pins (9 %), metal screws (4 %), bone pegs (4 %), osteochondral plugs (3 %) or bioabsorbable screws (2 %), as well as transarticular drilling with bioabsorbable pin fixation (3 %) and drilling with metal screw fixation (2 %).

Conclusion

The most common techniques were transarticular drilling for stable lesions and bioabsorbable pin fixation for unstable lesions. The key findings were that the vast majority of lesions healed postoperatively, regardless of technique, and that high-quality trials are required to more appropriately compare the effectiveness of techniques.

Level of evidence

Systematic review, Level IV.     

Biomechanical properties of femoral posterior cruciate ligament fixations

Purpose

The success of reconstructions of the posterior cruciate ligament (PCL) mainly depends on the fixation strength of the tendon–bone interface. Reliable data about the mechanical characteristics of PCL fixation techniques are sparse. The aim of this study was to investigate the biomechanical properties of different femoral PCL fixation techniques.

Methods

Fresh human cadaver quadriceps (Q) and hamstring (H) tendons were harvested and fixed into porcine femora with a press-fit fixation suturing the tendon over a bone bridge (group A), a novel implant post-fixation (group B) or an interference screw fixation (group C). Each group consisted of 10 specimens. The constructs were cyclically stretched and eventually loaded until failure. Elongation during cyclic loading, stiffness, failure mode and maximum failure load was evaluated.

Results

Elongation during cyclical loading was significantly larger between the 1st and the 20th cycle than between the 20th and the 500th cycle in all groups (p < 0.05). Maximum failure load was 409 ± 71 (336–517) N in group QA, 456 ± 58 (347–510) N in group QB, 548 ± 116 (400–798) N in group QC, 472 ± 114 N (316–676 N) in group HA, 494 ± 98 N (371–668 N) in group HB and 498 ± 87 N (391–687 N) in group HC (significantly higher for QB compared to QA, p < 0.05).

Conclusion

This is the first study investigating the biomechanical properties of femoral PCL fixations. Implant-free fixation techniques like press-fit or post-fixations are able to withstand equal biomechanical forces compared to interference screw fixation. The novel fixations described in this study can be considered as a reliable alternative for the reconstruction of PCL using either hamstring or quadriceps tendons.     

Poly-L-lactic acid — hydroxyapatite (PLLA-HA) bioabsorbable interference screws for tibial graft fixation in anterior cruciate ligament (ACL) reconstruction surgery: MR evaluation of osteointegration and degradation features

Purpose

We evaluated with magnetic resonance imaging (MRI) the degradation and osteointegration features of a new type of bioabsorbable interference (BioRCI) screw composed of poly-L-lactic acid and hydroxyapatite (PLLA-HA) used for tibial graft fixation in anterior cruciate ligament (ACL) reconstruction.

Materials and methods

Thirty-one patients underwent arthroscopic surgery for ACL reconstruction using doubled gracilis and semitendinosus tendons fixed to the tibial tunnel with PLLA-HA (BioRCI-HA) screws. Two groups of patients were evaluated, one group 10–13 months after surgery and the other after 30–40 months. The standard knee ligament evaluation form of the International Knee Documentation Committee (IKDC) was used for clinical assessment and MRI for the radiological assessment.

Results

MRI after 10–13 months revealed findings referable to healing and integration of the bone-graft-screw system, findings that disappeared at later follow-up examinations. The BioRCI-HA screw remained constantly visible in all patients, although with changes in signal intensity over time.

Conclusions

BioRCI-HA screws allow adequate primary stability and superior osteoconduction and biocompatibility in comparison with plain PLLA screws. The absence of ferromagnetic artefacts allows accurate MRI follow-up and adequate evaluation of ligament synovialisation, screw degradation and graft osteointegration.     

Femoral fixation of hamstring grafts in posterior cruciate ligament reconstruction: biomechanical evaluation of different fixation techniques: is there an acute angle effect?

BACKGROUND: The literature provides little biomechanical data about femoral fixation of hamstring grafts in posterior cruciate ligament reconstruction. HYPOTHESIS: A hybrid fixation technique with use of an undersized screw has sufficient strength to provide secure fixation of posterior cruciate ligament grafts. Additional aperture fixation with a biodegradable interference screw can prevent graft damage that might be caused by an acute angle on the edge of the femoral tunnel. STUDY DESIGN: Controlled laboratory study. METHODS: In part 1, extracortical fixation of posterior cruciate ligament reconstructions with quadrupled porcine flexor digitorum grafts to simulate human hamstring grafts was compared with hybrid fixation methods using 6-, 7-, and 8-mm screws. Groups were tested in cycling loading with the load applied in line with the bone tunnel. In part 2, extracortical fixation was compared with hybrid fixation using a 1-mm undersized screw anterior and posterior to the graft. Structural properties and graft abrasion were evaluated after cyclic loading with the load applied at 90 degrees to the tunnel. In each group, 8 porcine knees were tested. RESULTS: In part 1, stiffness, maximum load, and yield load were significantly higher for hybrid fixation than for extracortical fixation. Hybrid fixation with an 8-mm screw resulted in higher yield load than with a 7-mm screw. In part 2, graft laceration was more pronounced in specimens with extracortical fixation than with hybrid fixation. Posterior screw placement was superior to the anterior position. CONCLUSION: For all parameters, hybrid fixation with an interference screw provided superior structural results. No relevant disadvantages of undersized screws could be found. Graft damage due to abrasion at the edge of the femoral bone tunnel was reduced by use of an interference screw. The posterior screw placement seems favorable. CLINICAL RELEVANCE: Hybrid fixation of hamstring grafts in posterior cruciate ligament reconstruction is superior to extracortical fixation alone with no relevant disadvantages of undersized screws. The results raise the suspicion of an acute angle effect of the femoral bone tunnel.     

Interference screw insertion angle has no effect on graft fixation strength for insertional Achilles tendon reconstruction

Purpose

To compare the effect of two interference screw insertion angles on the biomechanical properties of the insertional Achilles tendon (IAT) reconstruction.

Methods

Nine matched pairs of fresh-frozen human cadaveric Achilles tendon specimens were randomized to two groups with interference screw insertion angles of 60° and 120°. The IAT reconstruction was performed by fixing the graft tendon with the interference screw. Each specimen was loaded to failure. The load at failure, stiffness, and mode of failure were documented. Differences in load at failure and stiffness were analysed.

Results

There was no statistically significant difference between the 60° and 120° groups for failure load (149.137?±?20.836 versus 155.428?±?28.343 N, respectively, n.s.) and stiffness (14.523?±?2.824 N/mm versus 14.727?±?2.192 N/mm, respectively, n.s.). The most common mode of failure was the graft pulling out of the bone tunnel when the screw broke.

Conclusions

Graft fixation at two different interference screw insertion angles for IAT reconstruction exhibited equivalent biomechanical performance. When performing this procedure, surgeons may choose the interference screw insertion angle based on personal preference.

     

Initial fixation strength of a hybrid technique for femoral ACL graft fixation

Aperture fixation with interference screws matching the diameter of the tunnel is associated with the risk of graft laceration and graft rotation. A hybrid fixation technique (extracortical and aperture fixation) with undersized interference screws provides a higher fixation strength when compared to an aperture fixation using only a screw matching the size of the tunnel and also reduces the risk of graft laceration. This research is an experimental laboratory study. We evaluated the initial fixation strength at time-zero of an extracortical-, a hybrid- and an aperture fixation in ACL reconstruction using extracortical buttons and different sized interference screws in porcine knees. The tests were performed using a single cycle and cyclic loading protocol. Analysis of yield load, maximum load and stiffness in the single cycle loading test showed no statistically significant differences for hybrid fixation with a 1 mm undersized screw and aperture fixation with a screw matching the size of the tunnel. Cyclic loading tests showed a statistically significant difference between hybrid and aperture fixation. The use of an undersized screw alone in aperture fixation resulted in insufficient fixation strength. The initial fixation strength of the hybrid technique with undersized screws is higher compared to an interference screw fixation alone. The hybrid fixation technique is an alternative for ACL graft fixation.     

Meta-analysis comparing bioabsorbable versus metal interference screw for adverse and clinical outcomes in anterior cruciate ligament reconstruction

Purpose

To compare bioabsorbable screw (BS) against metal screw (MS) primarily on adverse effects and secondarily on clinical outcomes after single-bundle primary anterior cruciate ligament reconstruction.

Methods

Electronic searches were performed using search strategies meeting the mentioned purposes. Retrieved articles were selected for randomised controlled trials (RCTs) reporting at least 1-year follow-up. Potential studies were selected under inclusion and exclusion criteria. Risk of biases and data extraction was completed by two review authors. Discrepancies were resolved through discussion. Mean difference and risk ratio with 95 % confidence interval (CI) were used for continuous and binary outcomes, respectively. Heterogeneity was assessed using I ². Pooled treatment effects with 95 % CI were estimated using the fixed- or random-effect model where appropriate.

Results

Eleven RCTs with 878 randomly allocated patients were included, and 711 patients (81 %) with eligible follow-up time up to 8 years were analysed. Comparing with the MS group, BS group using medial hamstring graft showed evidence of larger tunnel widening on the femoral side measured from radiographs or magnetic resonance imaging, though data could not be pooled because diverse measurement methods had been used. Significantly higher rates of effusion and screw breakage, and fewer cases of complete tunnel healing were reported in the BS group. Nevertheless, functional and clinical results were not deteriorated by the presence of these adverse effects for both short- and longer-term follow-ups.

Conclusion

This is the first systematic review focusing on adverse effects of the BS, such as larger tunnel widening and higher rates of other complications. With these effects, routine use of the BS should be balanced with the advantages claimed. Cost-effectiveness is another issue, and well-designed RCTs are needed to better validate the implication.

Level of evidence

Systematic review of randomised controlled therapeutic studies, Level II.     

The attic of the femoral tunnel in anterior cruciate ligament reconstruction: a comparison of outcomes of two suspensory femoral fixation systems

Purpose

This study aimed to find answers to the following questions: (1) Is it possible to determine and measure the space between the top of the graft and entrance of implant tunnel by magnetic resonance imaging (MRI)? (2) Is there any correlation between the hole above the graft in femoral tunnel and the femoral tunnel widening? (3) Does the tunnel widening affect clinical outcomes? (4) Are clinical and radiological outcomes of Toggle Loc with Zip Loop implant-loop design better than Endobutton CL?

Methods

The operative data of two surgeons were analysed. One surgeon used Endobutton CL femoral fixation (E-CL group, n = 46); the other used Toggle Loc with Zip Loop femoral fixation (TL-ZL group, n = 32). At the last follow-up, clinical evaluation was performed with International Knee Documentation Committee Subjective Knee Form (IKDC), Tegner activity scale, Lysholm score, active and passive ROM, Lachman and pivot shift tests, and KT-1000 arthrometer. Radiological evaluation including measurement of tunnel widening on X-ray and MRI and the height of attic of femoral tunnel (space above the graft in femoral tunnel) on MRI was performed.

Results

No difference was found in patient demographics, concomitant meniscal surgery and clinical outcomes. The femoral tunnel widening was evaluated significantly low in TL-ZL group on the PA X-ray and MRI. No difference was observed in the tibial tunnel widening on X-ray and MRI. A correlation between the height of attic of femoral tunnel and the femoral tunnel widening was determined. Thus, the greater the height of attic of femoral tunnel, the greater the femoral tunnel widening. No correlation was established between the tunnel widening and IKDC and Lysholm scores.

Conclusions

The results of this study demonstrate that a positive correlation exists between the height of the attic of the femoral tunnel and femoral tunnel widening. Therefore, increasing the height of the attic of the femoral tunnel may contribute to graft motion, which would then enhance femoral tunnel widening.

Level of evidence

III.     

Single-bundle transtibial posterior cruciate ligament reconstruction using a bioabsorbable cross-pin tibial back side fixation

Purpose

The purpose of this study was to examine a developed surgical technique by performing a mid-term evaluation of clinical and stability results and complications.

Methods

Thirty patients who underwent transtibial posterior cruciate ligament (PCL) reconstruction using a bioabsorbable cross-pin tibial back side fixation method were enrolled in this prospective study. Lysholm and International Knee Documentation Committee (IKDC) knee scales were used to evaluate clinical outcomes. Stability was evaluated using a Telos device with a 150 N force at 90 degrees of knee flexion. Follow-up magnetic resonance imaging (MRI) was also performed in 20 (66.7%) patients, and complications were evaluated. Those with complication by MRI were assigned to an abnormal MRI group.

Results

The follow-up period was 47 (range, 25–62) months. On comparing preoperative and final follow-up clinical results, Lysholm and IKDC knee scale scores were found to have improved significantly (P < 0.001). The mean side-to-side difference in posterior translation measured using a Telos device was 13.4 ± 3.1 mm (range 10–20 mm) preoperatively and 3.2 ± 1.5 mm (range 1–7 mm) at last follow-up, which represented a significant improvement in stability (P < 0.001). Five patients showed cyst formation in the tibial tunnel and two patients showed a significant signal increase at the anterior portion of the tibial tunnel, which was believed to indicate a pro-cystic status. The normal and abnormal MRI groups had similar Lysholm and IKDC knee scale scores and stress radiographs (P > 0.05).

Conclusions

Single-bundle transtibial PCL reconstruction using a bioabsorbable cross-pin tibial back side fixation was found to produce satisfactory clinical and stability results. However, despite these satisfactory results, a potential complication of tibial cyst formation was observed.

Level of evidence

Case series, Level IV.     

Biomechanics of a new technique for minimal-invasive coracoclavicular ligament reconstruction

Purpose

To evaluate the biomechanical properties of a new coracoclavicular (CC) ligament reconstruction using a subcoracoidal flip button and a tendon graft compared to an augmented tendon loop and a synthetic coracoclavicular ligament reconstruction.

Methods

A porcine metatarsalia model was used to assess supero-inferior fixation strength of (1) a new technique using an augmented tendon graft and a subcoracoidal flip button in a lifting block fashion, (2) an augmented tendon loop around the coracoid base and (3) a synthetic coracoclavicular ligament augmentation technique. Cyclic loading from 20 to 70 N for 1,000 cycles was performed, followed by a load-to-failure protocol.

Results

All specimens of the three different groups survived the cyclic loading protocol. The maximum loads to failure under superior loading conditions were 760 ± 78 N for group 1, 702 ± 48 N for group 2 and 1117 ± 91 N for group 3. The synthetic coracoclavicular ligament augmentation technique revealed significantly higher maximum loads compared to the other groups (p < 0.001). The augmented tendon graft/flip button construct had higher maximum loads than the augmented tendon loop (n.s.). No significant differences were found for stiffness and elongation behaviour among the 3 tested groups.

Conclusion

The results suggest that the described technique is an alternative option to reconstruct the CC ligaments in AC joint instability in a minimal-invasive technique. Under superior loading conditions, the biomechanical properties exhibited by this novel technique were comparable to those of the tendon loop around the coracoid base.     

Biomechanical analysis of femoral tunnel pull-out angles for anterior cruciate ligament reconstruction with bioabsorbable and metal interference screws

BACKGROUND: Fixation strength of metal and bioabsorbable interference screws has not been evaluated while varying the anterior cruciate ligament graft tension angle. HYPOTHESIS: There is no difference in fixation strength between 2 types of interference screws for anterior cruciate ligament graft fixation while the graft tension angle is varied relative to the femoral tunnel. STUDY DESIGN: Controlled laboratory study. METHODS: Forty-eight anterior cruciate ligament reconstructions were performed using immature porcine femurs stripped of soft tissue and doubled-over porcine flexor digitorum profundus tendon grafts. Specimens were randomized to bioabsorbable or titanium interference screw fixation. Specimens were randomized to one of three pull angles (0 degrees , 30 degrees , 60 degrees ) representing loading at different knee flexion angles (n = 8/group). Reconstructed ligaments were tensioned to 10 N followed by 200 loading cycles between 10 and 150 N and a final failure test. Construct elongation (mm) at 100 and 200 cycles and failure load (N) were analyzed using a 2-way analysis of variance (P < .05). RESULTS: Screw material interacted significantly with graft tension angle, as the bioabsorbable screw specimens demonstrated significantly greater fixation strength when tensioned at greater angles. Specimens fixed with bioabsorbable screws showed significantly less elongation at both 100 and 200 cycles and significantly greater failure load compared with titanium screws. CONCLUSION: Bioabsorbable interference screws acutely have increased fixation strength compared with titanium interference screws for anterior cruciate ligament grafts loaded at greater tension angles. CLINICAL RELEVANCE: The strength of anterior cruciate ligament reconstruction fixation increases with increasing divergence between the tension angle and femoral tunnel, a condition seen when the knee approaches full extension.     

Treatment and return to sport following a Jones fracture of the fifth metatarsal: a systematic review

Purpose

The aim of this study is to better inform the sports surgeon of current evidence for the treatment of Jones fractures of the base of the 5th metatarsal. The study aimed to establish what the outcomes were for different treatments modalities. By doing this, the clinician will be better prepared to institute a logical, evidence-based approach to the treatment of their patients with this injury.

Methods

A thorough literature search was performed from 1980 to present day. Studies were included based on set criteria and analysed for their validity, and their results were scrutinised. Jones fractures were segregated into acute fractures, delayed unions and non-unions.

Results

Twenty-six studies were included, of which 22 were level 4 evidence, with only 1 randomised controlled trial. Functional outcome data were limited to return to sports in most studies with few studies using established scoring systems. Return to sports following intra-medullary screw fixation for acute fractures ranged from 4 to 18 weeks. Acute fractures treated non-operatively had a union rate of 76 % (pooled), whereas in fractures treated with a screw it was 96 % (pooled). Delayed unions treated non-operatively had a union rate of 44 and 97 % treated operatively. Non-unions treated with screw fixation healed in 97 % of cases.

Conclusions

Although supported by mostly level 4 evidence, intra-medullary screw fixation is more likely to lead to successful union of all types of Jones fractures compared to non-operative treatments. Early return to play in athletes prior to full radiological union is not advised in case of re-fracture.

Level of evidence

IV.     

Biomechanical comparison of three techniques for fixation of tibial avulsion fractures of the anterior cruciate ligament

Purpose

To evaluate the initial stability of a suture anchor fixation and to compare this with a screw fixation and pull-out suture fixation for anterior cruciate ligament tibial avulsion fracture.

Methods

The initial fixation strength of 3 different fixation techniques, antegrade cannulated screw fixation, pull-out suture fixation with Ethibond and bioabsorbable knotless suture anchor fixation, was evaluated. Using 14 fresh cadavers (28 knees), the strength to failure, initial displacement and mode of failure were measured.

Results

The strength to failure of the suture anchor fixation was not significantly different from that of the screw fixation and was higher than that of the pull-out suture fixation. The initial displacement of the suture anchor fixation was lower than that of the screw fixation and the pull-out suture fixation. The majority of the suture anchor fixations and the screw fixations were failed by pull-out from the bone. Eight of the 56 suture anchor fixations failed by pull-out of the suture from the ligament proper. And, one of the 7 screw fixations failed due to fracture of the avulsed bony fragment. All of the pull-out suture fixations failed by suture material rupture.

Conclusions

These biomechanical results suggest that the initial fixation strength of suture anchor fixation was not less than that of screw fixation or pull-out suture fixation. And, the initial displacement of suture anchor fixation was lower than that of screw fixation or pull-out suture fixation. The suture anchor fixation appears to be a good alternative fixation technique for repair of anterior cruciate ligament tibial avulsion fracture.     

Effect of femoral tunnel position on graft tension curves and knee stability in anatomic double-bundle anterior cruciate ligament reconstruction

Purpose

To evaluate the effect of the femoral tunnel position of the anteromedial bundle (AMB) and the posterolateral bundle (PLB) on the graft tension curves and knee stability in anatomic double-bundle anterior cruciate ligament (ACL) reconstruction.

Methods

Forty-five patients who underwent anatomic double-bundle ACL reconstruction were included. AMB and PLB were provisionally fixed to a graft tensioning system in the following settings during surgery: (1) AMB at 20° and PLB at 0° (A20P0), (2) AMB at 20° and PLB at 20° (A20P20), and (3) AMB at 20° and PLB at 45° (A20P45). Bundle tension was recorded during knee flexion–extension. A pivot shift test was also evaluated. Femoral tunnel positions of the AMB and PLB were then assessed by three-dimensional computed tomography, and the correlation between femoral tunnel position and tension change pattern or residual pivot shift was evaluated.

Results

The depth of the PLB tunnel position was correlated with the extent of tension reduction in the PLB between 0° and 30° irrespective of graft fixation settings, while neither the AMB tunnel position nor the height of the PLB tunnel position affected the tension change pattern. Ten cases showed grade 1 pivot shift only in the A20P0 setting. The PLB tunnel position in the pivot shift-positive cases was significantly deeper than that in the pivot shift-negative cases (27.5 ± 6.2 and 34.1 ± 5.5 %, respectively, P = 0.002).

Conclusions

In anatomic double-bundle reconstruction, deeper PLB tunnel position was correlated with the larger tension reduction in the PLB between 0° and 30°. Fixation of the AMB at 20° and the PLB at 0° resulted in residual pivot shift phenomenon in 10/45 cases, and the PLB tunnel position in the pivot shift-positive cases was significantly deeper than that in the pivot shift-negative cases. In anatomic double-bundle reconstruction, the placement of PLB femoral tunnel must not be too deep, as it might lead to significant tension reduction in the PLB near extension and thus insufficient tension in the PLB, resulting in residual pivot shift phenomenon.

Level of evidence

IV.     

The effect of anterior cruciate ligament graft orientation on rotational knee kinematics

Purpose

To determine whether coronal graft orientation and tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is associated with tibial rotation excursion during functional activities.

Methods

Eighty-four patients who had undergone ACL reconstruction over a ten-year time span had tibial rotation measured during level walking, using a three-dimensional motion analysis system. Fifty-two patients also had measures taken during the more dynamic task of single-limb landing. During the 10-year period, the position of the graft was deliberately changed from a vertical to more horizontal orientation in the coronal plane. Post-operative radiographs were analysed for the coronal graft orientation and femoral and tibial tunnel positions. Radiographic measurements of graft orientation and tunnel position were then correlated with the amount of tibial rotational excursion recorded during the walking and landing tasks.

Results

For the single-limb landing task, a significant positive correlation was observed between the coronal graft angle and rotational excursion (R = 0.35, R ²  = 0.12, p = 0.01). This indicated greater rotational excursion was associated with vertical graft orientation, but only explained 12 % of the variance. No correlations were found between coronal graft angle and tibial rotation during level walking.

Conclusions

These findings support the notion that ACL graft orientation may play a role in rotational kinematics of the ACL-reconstructed knee, particularly during higher impact activities.

Level of evidence

IV.