The science of reconstruction of the anterior cruciate ligament

A pilot clinical evaluation comparing the Mitek bone-tendon-bone cross pin and bioabsorbable screw in anterior cruciate ligament reconstruction fixation, a randomized double blind controlled trial

PURPOSE

To compare the clinical efficacy of ACL reconstruction using the Mitek bone-tendon-bone cross pin (RIGIDfix) to the Linvatec Bioscrew (control device).

METHODS

Forty subjects were randomized into one of two groups: the RIGIDfix or control group. Eligible subjects were male and female, 18 years of age and older, with an ACL injury of at least 3 weeks duration and no evidence of ACL insufficiency on the contralateral side. Subjects were followed for 24-month post-operatively. Evaluations included the International Knee Documentation Committee (IKDC) Knee Ligament Standard Evaluation, Mohtadi's ACL Deficiency Quality of Life (ACL-QOL) questionnaire and the attainment of six rehabilitation milestones. Subjects and assessors were blinded to the surgical device used.

RESULTS

Four subjects in the RIGIDfix group and four controls were lost to follow-up. The change in final IKDC scores did not differ significantly between groups with the majority demonstrating an improvement of one to two grades. The change in ACL-QOL scores did not differ significantly between the RIGIDfix subjects (40.0+4.4) and controls (46.0+3.6). Furthermore, the number of weeks that the RIGIDfix subjects versus controls attained full active extension, functional range of motion, normal gait, stair climbing, running gait and sprinting did not differ significantly.

CONCLUSIONS

The RIGIDfix results in a similar post-operative course to the control device and is efficacious for the reconstruction of the ACL. No adverse events were associated with the use of the RIGIDfix. The results of this study should be considered preliminary due to the small sample size.

Arthroscopic ACL reconstruction with Delta plasty: an innovative approach with hamstrings' transfer and double tibial tunnel

We propose a new technique, with double bundle, double tibial tunnels with a bridge between them, using the hamstrings as auto-grafts, retaining either their central or peripheral attachment. A prospective series of 41 patients underwent primary reconstruction of the anterior cruciate ligament by one surgeon, arthroscopically and electronically assisted; 37 were men and 4 were women with a mean age of 24.7 years. The mean follow-up was 19.05 (12-30) months. Normal function and joint stability was achieved. The patients returned to full occupational activities within 3-6 months after the operation. The function of hamstrings was not disturbed. Two patients have sustained a new injury without rupture of the grafts. The Noulis-Lachman test was negative in 35 knees. Positive Pivot shift, post-operatively, was present in 15.45% of patients. The IKDC score was 84.55. In the proposed ACL reconstruction technique, the two tendons are transferred and used as grafts, with gracillis and semitendinosus retaining their distal and central attachment, respectively; the former superimposed upon the latter while entering the femoral tunnel. The tibial tunnels leave a bone bridge ranging between 12 and 15 mm within the footprints of ACL. The two bundles are tensioned, each at different angle. This configuration imitates both the anatomy and the function of ACL and controls not only the anterior translation, but also the rotatory stability. With this innovative technique, the final outcome is improved, thus being closer to normal, as evidenced from previous experiments and the present prospective series.

Double-bundle anterior cruciate ligament reconstruction: a computer-assisted orthopaedic surgery study

BACKGROUND

The biomechanical function of single-bundle anterior cruciate ligament reconstruction, in cadaveric studies, is successful in limiting anterior tibial translation in response to an anterior tibial load but seems to be insufficient to control a combined rotator load of internal and valgus torque. Anatomical double-bundle anterior cruciate ligament reconstruction might produce a better biomechanical outcome.

HYPOTHESIS

The addition of the posterolateral bundle to the anteromedial bundle, in an in vivo double-bundle computer-assisted anterior cruciate ligament reconstruction, is able to reduce internal rotation of the tibia at 30 degrees of knee flexion, compared with a standard single-bundle reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty consecutive anterior cruciate ligament reconstructions were performed in male patients in April and May 2006 with double-bundle gracilis and semitendinosus tendon grafts using the 2.0 OrthoPilot navigation system. Group A (10 patients) underwent standard single-bundle anterior cruciate ligament reconstruction with doubled gracilis and semitendinosus tendon graft; group B (10 patients) underwent double-bundle reconstruction with doubled gracilis and semitendinosus tendon graft. Anteroposterior displacement and internal and external rotation at 30 degrees of knee flexion were evaluated before and after reconstruction, using manual maximum force.

RESULTS

Both techniques significantly reduced anteroposterior displacement and internal and external rotation of the tibia with respect to preoperative anterior cruciate ligament-deficient condition (P < .05). Comparing groups, no differences in anteroposterior tibial displacement and internal and external rotation of the tibia were found (anteroposterior, 3.7 mm and 5.2 mm; internal rotation, 16.3 degrees and 16.6 degrees; external rotation, 15.7 degrees and 15.1 degrees, respectively) in group A and B (P = .06, .90, and .72, respectively).

CONCLUSION

The hypothesis that addition of the posterolateral bundle to the anteromedial bundle is able to reduce internal rotation of the tibia at 30 degrees of knee flexion is not confirmed.

CLINICAL RELEVANCE

The effective role of the anatomical double-bundle procedure in better restoring knee kinematics should be questioned in an in vivo model.

Jump-landing direction influences dynamic postural stability scores

The purpose of this investigation was to determine dynamic postural stability differences among forward, diagonal, and lateral single leg-hop-stabilization protocols in healthy subjects. A one-within repeated measures design was used to determine the effects of jump direction on dynamic postural stability during landing. Subjects were required to perform a two-legged forward, diagonal, and lateral jump to a height equivalent to 50% of their maximum vertical leap, land on a single leg and balance for three seconds. Twenty-six subjects [10 males (22+/-3.9 years of age, 70.9+/-7.6kg, and 176.8+/-6.5cm) and 16 females (20.6+/-.5 years of age, 65.6+/-9.1kg, and 166.4+/-5.9cm)] volunteered to participate in this investigation. Dynamic postural stability indices for the anterior/posterior, medial/lateral, and vertical planes were collected during jump-landing trials of each direction. The results of the investigation show that medial/lateral and vertical dynamic postural stability were significantly affected by the direction of the jump. More specifically, lateral and diagonal jump-landings produce increased medial/lateral stability index (MLSI) scores and forward jump-landings produce increased vertical stability index (VSI) scores. The results suggest that in a healthy population, jump protocol direction will statistically affect dynamic postural stability in the frontal and vertical planes. These alterations could be exacerbated in individuals with lower extremity impairments and further research is warranted.

ACL reconstruction using the Rigidfix femoral fixation device via the anteromedial portal: a cadaver study to evaluate chondral injuries

The aim of this anatomic descriptive cadaver study is to evaluate the entrance points of cross-pins and the possible chondral damages, using a two cross-pin femoral fixation device via anteromedial portal, during anterior cruciate ligament (ACL) reconstruction. Twenty fresh-frozen cadaver knees (12 cadavers) were tested. We employed the Rigidfix Cross Pin device (Mitek, Norwood, MA), designed to use two biodegradable pins (PLA, length 42 mm, diameter 2.7 mm). Instead of PLA pins, we used color coded metallic pins. Femoral tunnel drilling and cross-pin guide insertions were performed through the anteromedial portal. We gave three positions to the cross-pin guide: 0 degrees , 45 degrees and 90 degrees slope, referring to the horizontal plane. Per each position, we inserted two metallic pins. We recorded and subdivided the pin holes, in three different groups: Group A (0 degrees ); B (45 degrees ); C (90 degrees of slope). Then a wide dissection has been implemented. Group A: 6 knees (30%) had two pins inside the cartilage of the lateral femoral condyle; 10 knees (50%) had one pin inside the cartilage; and 4 knees (20%) had both pins out of the cartilage. Group B: 7 knees (35%) had two pins inside the cartilage; 12 knees (60%) had one pin inside the cartilage; and one knee (5%) had both pins out of the cartilage. Group C: 7 knees (35%) had two pins inside the cartilage; and 13 knees (65%) had one pin inside the cartilage. The risk of chondral injury, using this technique, is high: from 80% (group A) to 100% (Group C) to have at least one pin inside the cartilage. The use of Rigidfix via AM portal is not recommended for routine ACL reconstruction.

Arthroscopic anterior cruciate ligament reconstruction using fresh-frozen bone plug-free allogeneic tendons: 10-year follow-up

PURPOSE

To evaluate the long-term outcomes following arthroscopic-assisted anterior cruciate ligament (ACL) reconstruction using fresh-frozen allogeneic tendon.

METHODS

Sixty-one athletically active patients (mean age at surgery, 20.9 years) who had arthroscopic-assisted ACL reconstruction using fresh-frozen free tendon allograft underwent physical examination, instrumented laxity measurement, radiographs, and thigh muscle strength at 10 to 14 years (mean, 11.5) postoperatively, and these data were compared with results of similar measurements obtained at 2 years postoperatively.

RESULTS

Lachman test and pivot shift test were maintained as negative in 53 (87%) and 52 (85%) patients at follow-up, respectively. Quantitative measurements using the KT-2000 knee arthrometer showed 1.6 +/- 1.3 (mean +/- SD) mm in the side-to-side difference, and no more than 3 mm in 56 patients (92%) at final follow-up. All but one was assessed as normal or nearly normal by International Knee Documentation Committee score. Patient activity level was decreased at the long-term follow-up, but this change was mainly associated with changes in social context (e.g., graduation from school) rather than with knee limitations. None of the patients experienced deep infection or graft rejection. Degenerative joint disease on radiographs was seen in 13 out of 15 patients (87%) whose menisci had been excised, whereas it was observed in 12 out of 46 (26%) whose menisci had been preserved.

CONCLUSIONS

A series of 61 patients with fresh-frozen bone plug-free tendon allografts using a 2-incision technique for arthroscopic ACL reconstruction results in long-term knee stabilization and functioning among young active individuals while simultaneously avoiding graft harvest site morbidity.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Landing mechanics between noninjured women and women with anterior cruciate ligament reconstruction during 2 jump tasks

BACKGROUND

Women with anterior cruciate ligament reconstruction have different neuromuscular strategies than noninjured women during functional tasks after ligament reconstruction and rehabilitation.

HYPOTHESIS

Landing from a jump creates high loads on the knee creating dynamic instability in women with anterior cruciate ligament reconstruction, whereas noninjured women have stable knee landing mechanics.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fifteen noninjured women and 13 women with anterior cruciate ligament reconstruction performed 5 trials of a single-legged 40-cm drop jump and 2 trials of a 20-cm up-down hop task. Multivariate analyses of variance were used to compare hip and knee joint kinematics, knee joint moments, ground-reaction forces, and electromyographic findings between the dominant leg in noninjured women and reconstructed leg in women with anterior cruciate ligament reconstruction.

RESULTS

No statistically significant differences between groups were found for peak hip and knee joint angles for the drop jump task. Statistically significant differences in neuromuscular activity (P = .001) and anterior-posterior knee shear forces (P < .001) were seen in women with anterior cruciate ligament reconstruction compared with noninjured women in the drop jump task. However, no statistically significant differences (P > .05) between groups were found for either peak hip and knee joint angles, peak joint kinetics, or electromyographic findings during the up-down hop task.

CONCLUSION

Women with anterior cruciate ligament reconstruction have neuromuscular strategies that allow them to land from a jump similar to healthy women, but they exhibit joint moments that could predispose them to future injury if they participate in sports that require jumping and landing.

Predictors of proximal tibia anterior shear force during a vertical stop-jump

Anterior cruciate ligament (ACL) continues to be a significant medical issue for athletes participating in sports and recreational activities. Biomechanical analyses have determined that anterior shear force is the most direct loading mechanism of the ACL and a probable component of noncontact ACL injury. The purpose of this study was to examine the biomechanical predictors of proximal tibia anterior shear force during a stop-jump task. A biomechanical and electromyographic (EMG) analysis of the knee was conducted while subjects performed a vertical stop-jump task. The task was chosen to simulate an athletic maneuver that included a landing with a sharp deceleration and a change in direction. The final regression model indicated that posterior ground reaction force, external knee flexion moment, knee flexion angle, integrated EMG activity of the vastus lateralis, and sex (female) would significantly predict proximal tibia anterior shear force (p < 0.0001, R2 = 0.8609). Knee flexion moment had the greatest influence on proximal tibia anterior shear force. The mathematical relationships elucidated in the current study support previous clinical and basic science research examining noncontact ACL injuries. This data provides important evidence for clinicians who are examining the risk factors for these injuries and developing/validating training programs to reduce the incidence of injury.

A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen

PURPOSE

The literature has shown that anterior cruciate ligament (ACL) tear rates vary by gender, by sport, and in response to injury-reduction training programs. However, there is no consensus as to the magnitudes of these tear rates or their variations as a function of these variables. For example, the female-male ACL tear ratio has been reported to be as high as 9:1. Our purpose was to apply meta-analysis to the entire applicable literature to generate accurate estimates of the true incidences of ACL tear as a function of gender, sport, and injury-reduction training.

METHODS

A PubMed literature search was done to identify all studies dealing with ACL tear incidence. Bibliographic cross-referencing was done to identify additional articles. Meta-analytic principles were applied to generate ACL incidences as a function of gender, sport, and prior injury-reduction training.

RESULTS

Female-male ACL tear incidences ratios were as follows: basketball, 3.5; soccer, 2.67; lacrosse, 1.18; and Alpine skiing, 1.0. The collegiate soccer tear rate was 0.32 for female subjects and 0.12 for male subjects. For basketball, the rates were 0.29 and 0.08, respectively. The rate for recreational Alpine skiers was 0.63, and that for experts was 0.03, with no gender variance. The two volleyball studies had no ACL tears. Training reduced the ACL tear incidence in soccer by 0.24 but did not reduce it at all in basketball.

CONCLUSIONS

Female subjects had a roughly 3 times greater incidence of ACL tears in soccer and basketball versus male subjects. Injury-reduction programs were effective for soccer but not basketball. Recreational Alpine skiers had the highest incidences of ACL tear, whereas expert Alpine skiers had the lowest incidences. Volleyball may in fact be a low-risk sport rather than a high-risk sport. Alpine skiers and lacrosse players had no gender difference for ACL tear rate. Year-round female athletes who play soccer and basketball have an ACL tear rate of approximately 5%.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Clinical outcomes of allograft versus autograft in anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) injuries are the most common complete ligamentous injury to the knee. The optimal graft should be able to reproduce the anatomy and biomechanics of the ACL, be incorporated rapidly with strong initial fixation, and cause low graft-site morbidity. This article reviews the literature comparing the clinical outcomes following allograft and autograft ACL reconstruction and examines current issues regarding graft choice.

Measurement of the graft angles for the anterior cruciate ligament reconstruction with transtibial technique using postoperative magnetic resonance imaging in comparative study

The aims of this study were to quantify the angle and placement of an anterior cruciate ligament (ACL) grafted with a single incision ACL reconstruction technique using postoperative magnetic resonance imaging (MRI), and to compare the results with those with a native ACL. Between February 1996 and May 2004, 96 consecutive patients, who had undergone postoperative MRI of the knee followed by an arthroscopically assisted ACL reconstruction with either a hamstring tendon or bone-patellar tendon-bone (BTB) autograft, were enrolled in this study. The femoral tunnel was drilled using the transtibial technique. The patients were divided into two groups; the hamstring tendon graft group (group H; 50 patients) and the BTB graft group (group B; 46 patients). All the patients including both groups in this study underwent postoperative MRI and were followed up for a minimum of 2 years. The control group (group C) consisted of 50 patients whose meniscus tear had been operated on by arthroscopy and whose ACL was intact. The orientation of the ACL ligament or graft was measured using three different methods: the sagittal ACL angle, the ACL-Blumensaat line angle, and the coronal ACL angle. The mean sagittal ACL angle in group C (58.7 +/- 3.8 degrees ) was significantly lower than in groups H (64.6 +/- 4.2 degrees ) and B (71.3 +/- 6.0 degrees ). The mean ACL-Blumensaat line angle in group C (8.6 +/- 3.6 degrees ) was also significantly lower than in groups H (12.8 +/- 5.2 degrees ) and B (18.0 +/- 5.3 degrees ). The mean coronal ACL angle in group C (65.9 +/- 4.4 degrees ) was lower than that in groups H (73.5 +/- 2.4 degrees ) and B (75.2 +/- 2.9 degrees ). The grafted ACL of the hamstring tendon and BTB grafts on the postoperative MRI showed a significant vertical angle in the coronal and sagittal plane compared with the native ACL. In the sagittal plane, the hamstring tendon graft was positioned more obliquely than the BTB graft, which had a larger angle of the tibial tunnel, in an attempt to prevent a graft-tunnel mismatch. The postoperative MRI study showed that the more horizontally the angle of the tibial tunnel can be placed in a single incision ACL reconstruction, the more efficiently it can produce a graft closer to the native ACL.

Genetic engineering for skeletal regenerative medicine

The clinical challenges of skeletal regenerative medicine have motivated significant advances in cellular and tissue engineering in recent years. In particular, advances in molecular biology have provided the tools necessary for the design of gene-based strategies for skeletal tissue repair. Consequently, genetic engineering has emerged as a promising method to address the need for sustained and robust cellular differentiation and extracellular matrix production. As a result, gene therapy has been established as a conventional approach to enhance cellular activities for skeletal tissue repair. Recent literature clearly demonstrates that genetic engineering is a principal factor in constructing effective methods for tissue engineering approaches to bone, cartilage, and connective tissue regeneration. This review highlights this literature, including advances in the development of efficacious gene carriers, novel cell sources, successful delivery strategies, and optimal target genes. The current status of the field and the challenges impeding the clinical realization of these approaches are also discussed.

Biomaterials and scaffolds for ligament tissue engineering

Tissue engineering has achieved much progress in an attempt to improve and recover impaired functions of tissues and organs. Although many studies have been done, progress for tissue-engineered anterior cruciate ligaments (ACLs) has been slow due to their complex structures and mechanical properties. In this review, the ACL anatomical structure, progresses achieved, material selection, structure design, and future direction have been discussed, while the challenges and requirements from materials and scaffolds are highlighted. There is a considerably huge amount work that needs to be carried out; as such, future direction in ligament tissue engineering is proposed in hope that this review will give information on future ligament tissue engineering.

Double bundle or single bundle plus extraarticular tenodesis in ACL reconstruction? A CAOS study

Anatomic reconstructions of anterior cruciate ligament (ACL) with double bundle gracilis and semitendonosus tendons graft, reproducing AM and PL bundles, have been introduced to offer a better biomechanical outcome, especially during rotatory loads. On the other hand, many methods of tenodesing the lateral aspect of the tibia to the femur to reduce internal rotation (IR) of the tibia and minimize anterior translation of the tibia relative to the femur as a backup for intra-articular reconstruction, have been also suggested. The goal of this study is to evaluate the effect, on the IR of the tibia, of a lateral reconstruction in addition to a standard single bundle ACL reconstruction as compared with an anatomic double bundle ACL reconstruction. Computer assisted ACL reconstruction has been used because it could be very effective in evaluating the global kinematic performance of the reconstructed knee. We selected 20 consecutive ACL reconstruction procedures to be performed in males in our hospital. Patients were alternately assigned to one of the two groups--group A: standard single bundle ACL reconstruction with doubled gracilis and semitendinosus tendons graft with an arthroscopically assisted two incisions technique and a lateral extraarticular reconstruction; group B: double bundle ACL reconstruction with doubled gracilis and semitendinosus tendons graft with an arthroscopically assisted two incisions technique. In all ACL reconstruction procedures navigation process was performed. Both surgical techniques reduced significantly AP displacement, IR and external rotation (ER) of the tibia respect to pre-operative ACL deficient condition (p<0.05). Comparing the group A after the single bundle reconstruction and the group B after the AM bundle fixation, non differences were found in AP displacement, IR and ER of the tibia (p=0.75, p=0.07 and p=0.07 respectively; power: 0.94). Comparing the group A after the addition of the lateral tenodesis and group B after the PL bundle fixation (AM+PL) no differences in AP tibial displacement and in ER of tibia were found (p=0.9 and 0.15, respectively; power: 0.99); however a significant reduction in IR of the tibia was found in group A after the addition of the lateral tenodesis respect to the group B after the addition of the PL bundle (p=0.0001; power: 0.26). On the basis of our study, the addition of a lateral extraarticular reconstruction to a standard single bundle ACL reconstruction with hamstrings tendons graft in an "in vivo" reconstruction, is more effective in reducing the IR of the tibia at 30 degrees of knee flexion, as compared with a standard single bundle ACL reconstruction and with an anatomic double bundle reconstruction is confirmed.

ACL Tears in Female Athletes

With the growing number of female athletes, an increase is occurring in the number of sports-related injuries, which can cause physical, psychological, academic, and financial suffering. Female athletes are reported to be two to eight times more likely to sustain an anterior cruciate ligament (ACL) injury than male athletes. Further research on risk factors and preventative strategies for the female ACL is needed, because the cause of the disparity in injury rates remains equivocal and controversial. Individualized treatment for the injured knee is necessary and can include either conservative treatment or reconstructive surgery.

A literature review of autograft and allograft anterior cruciate ligament reconstruction

Knee anterior cruciate ligament reconstructive surgery has significantly evolved and now includes the option of using an allograft. This has resulted in numerous studies evaluating the advantages and disadvantages of allografts. The purpose of this literature review is to evaluate this research and present important findings to allow the selection of the most appropriate graft source when considering allograft versus autograft reconstruction.

Effects of hyperbaric oxygen on gene expressions of procollagen, matrix metalloproteinase and tissue inhibitor of metalloproteinase in injured medial collateral ligament and anterior cruciate ligament

Animal experiments were performed to investigate whether and how the administration of hyperbaric oxygen (HBO) affects gene expressions of procollagens, matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in injured medial collateral ligament (MCL) and anterior cruciate ligament (ACL). In 64 Sprague-Dawley rats, the MCL of the left knee was lacerated at the midsubstance, and the ACL of the left knee was lacerated adjacent to the tibial insertion in another 64 rats. Of these, 32 rats with lacerated MCL and 32 rats with lacerated ACL were housed in individual cages at normal atmospheric pressure (Groups MC and AC, respectively), while the remaining 64 rats were exposed to 100% oxygen at 2.5 atmospheres absolute for 2 h for 5 days a week (Groups MH and AH, respectively). Rats were sacrificed at 3, 7, 14 and 28 days postoperatively. After macroscopic examination, bilateral MCLs were harvested from Groups MC and MH, and bilateral ACLs from Groups AC and AH. Total RNA was extracted from each specimen and gene expressions of type I and type III procollagens, MMP-2, -9 and -3, and TIMP-1 and -2 were estimated using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). Macroscopically, lacerated MCL healed by scar tissue formation, the amount of which appeared to be greater in Group MH than in Group MC. In contrast, no lacerated ACLs united, and little, if any, differences were apparent in macroscopic findings between Groups AH and AC. Gene expression of type I procollagen was significantly greater in Group MH than in Group MC at 7 days postoperatively and was also significantly greater in Group AH than in Group AC at 28 days (P<0.05). No significant differences in type III procollagen gene expression were noted between Groups MH and MC or between Groups AH and AC. In addition, no significant differences in gene expressions of MMPs were seen in either ligament, except that gene expression of MMP-13 was significantly lower at 7 days in Group MH than in Group MC (P<0.05). Gene expressions of TIMPs did not differ significantly between Groups MH and MC in each time interval, whereas gene expressions of TIMPs were significantly greater in Group AH than in Group AC at 7, 14 and 28 days for TIMP-1 and at 3, 7 and 14 days for TIMP-2 (P<0.05). RT-PCR results suggested that HBO enhances structural protein synthesis and inhibits degradative processes by enhancing TIMP activities in the lacerated ACL. However, none of the lacerated ACLs united macroscopically despite administration of HBO, indicating that the effect of HBO is insufficient for healing of the injured ACL. If HBO therapy is used as an adjunctive therapy after primary repair of the injured ACL, the success rate of surgery seems likely to be increased.

Soft tissue tendon graft fixation in serially dilated or extraction-drilled tibial tunnels: a porcine model study using high-resolution quantitative computerized tomography

BACKGROUND

Tibial tunnel preparation may contribute to improved soft tissue graft fixation.

HYPOTHESIS

Step dilation produces greater tunnel wall bone volume than does extraction drilling and increases fixation strength. Bioabsorbable interference screw divergence decreases fixation strength, regardless of tunnel preparation method.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty porcine tibias were divided into 2 groups of 10 with matching mean apparent bone mineral density. One group received 9-mm-diameter extraction-drilled tunnels, and the other group received 7-mm-diameter extraction-drilled tunnels followed by step dilation to 9 mm. High-resolution quantitative computerized tomography scans and voxel analysis techniques determined tunnel wall bone volume fraction. Screws secured 8.5-mm-diameter porcine grafts in the tunnels. Repeat scans were used to determine screw divergence. Cyclic loading was performed in a servohydraulic device before load to failure testing.

RESULTS

The step dilation group had greater tunnel wall bone volume/total volume than did the extraction drilled group; however, a significant increase in fixation strength was not detected. Specimens with screw divergence angles less than 15 degrees had superior fixation and insertion torques compared with specimens with angles 15 degrees or more. Screw divergence correlated more strongly with fixation strength than did mean apparent bone mineral density or screw insertion torque.

CONCLUSION

Step dilation increased tunnel wall bone volume/total volume, but fixation strength did not improve. Screw divergence >or=15 degrees decreases graft-bone tunnel fixation whether or not step dilation is performed.

CLINICAL RELEVANCE

Screw alignment plays a greater role in anterior cruciate ligament graft fixation than does extraction drilling or step dilation tunnel preparation methods in healthy bone.

A new device for the fixation of anterior cruciate ligament tendon grafts

In this paper the design and experimental analysis is presented of a new fixation device of anterior cruciate ligament (ACL) grafts of the knee. This device is inserted into the bone tunnel, after the graft, in the same way as an interference screw. However, the fixation device described in this paper has been designed in such a way that, after the insertion of a threaded element in its interior, some of its components expand in a radial direction, pressing against the walls of the bone tunnel and thereby increasing the fixation of the graft. This expansion device can be used in both the femur and the tibia. The device proposed in this paper was compared with an interference screw for load failure and fixation stiffness in experiments performed using porcine bones. The failure load was significantly higher in the new expansion device group (633+/-202 N) than in the interference screw group (471+/-179 N). The stiffness obtained when the new device was used (59+/-20 N/mm) was also significantly higher than that obtained using the interference screw (37+/-19 N/mm) (t-test, P<0.05). According to these results, this new device could be considered a good alternative to improve fixation of anterior cruciate ligament grafts.

Comparison of direct and indirect interference screw fixation for tendon graft in rabbits

For ACL reconstruction, interference screw can fix the graft in the bone tunnel closer to the articular surface. However, direct interference screw fixation has a possibility to damage the tendon graft at the time of screw insertion, and the bone-tendon contact area is limited within the tunnel. To avoid the damage to the tendon graft at the time of screw insertion and to increase the bone-tendon contact area, a free bone plug was interposed between screw and tendon graft (indirect interference screw fixation). The purpose of this study was to compare ultimate load strength and histological findings between two techniques in a rabbit model. Ultimate pull-out load tests and histological examinations were evaluated at time 0, 3 and 6 weeks. The ultimate failure load of indirect interference screw fixation was significantly higher than that of direct interference screw fixation immediately after surgery (P < 0.05). Histologically, the interface tissues between tendon graft and host bone were more organized and matured in indirect technique. These findings showed that indirect interference screw fixation for tendon graft increased fixation strength at the graft-bone interface, providing quicker graft-bone healing.

Initial and 6 weeks postoperative structural properties of soft tissue anterior cruciate ligament reconstructions with cross-pin or interference screw fixation: an in vivo study in sheep

PURPOSE

The purpose of this study was to evaluate the detrimental effects of interference screw fixation on soft tissue anterior cruciate ligament (ACL) reconstruction after 6 weeks and compare them with a cross-pin technique.

METHODS

In an intra-articular model, ovine soft tissue grafts were fixed with two 3.3-mm biodegradable pins or with interference screws. Maximum load, yield load, and stiffness of the femur-graft-tibia complex were evaluated immediately after surgery and 6 weeks postoperatively.

RESULTS

For knees with interference screw fixation, strength deteriorated by 81% and stiffness deteriorated by 67%. For knees with double cross-pin fixation, strength deteriorated by 48% and stiffness improved by 52%. These differences were statistically significant. At the time of surgery, all grafts failed by slippage of the graft past the screw or by cross-pin failure. At 6 weeks postoperatively, the grafts of both groups failed at the tibial or femoral tunnel entrance.

CONCLUSIONS

After 6 weeks, the biomechanical characteristics of grafts that were fixed with cross-pins were superior to those of grafts after interference screw fixation.

CLINICAL RELEVANCE

Because of significantly inferior biomechanical stability after interference screw fixation, a less aggressive program of rehabilitation might be recommended.

Collagen Synthesis in tenocytes, ligament cells and chondrocytes exposed to a combination of Glucosamine HCl and chondroitin sulfate

Clinical testing of the nutraceuticals glucosamine (glcN) and chondroitin sulfate (CS) has shown efficacy in providing relief from symptoms in osteoarthritic patients. In vitro and in vivo studies support existence of a synergistic relationship upregulating synthetic activity in chondrocytes. A combination of glcN and CS may also be useful as adjunct therapy in sports-related injuries if similar upregulation of collagen synthesis is elicited in accessory ligament and tendon joint tissue. Collagen and non-collagenous protein (NCP) synthesis in cultures of bovine tenocytes, ligament cells and chondrocytes exposed to glcN + CS were assayed by uptake of radiolabeled proline into collagenase-sensitive material. Assay of radiolabel in hydroxyproline (a specific marker for collagen synthesis) following HPLC isolation confirmed the specificity of the metabolic effect. Synthesis of total collagenase-sensitive material was maximally upregulated at physiologically obtainable doses of glcN + CS. Tissue response followed the sequence ligament cells (+69%) > chondrocytes (+56%) > tenocytes (+22%). Labeled hydroxyproline increased by 132% in ligament cells, 27% in tenocytes and 49% in epitendon cells after a 48 h exposure to 5 μg ml⁻¹ glcN + 4 μg ml⁻¹ CS. Low dose combinations of glcN and CS effectively stimulate in vitro collagen and NCP synthesis by ligament cells, tenocytes and chondrocytes. Hence, therapeutic use following accessory joint tissue trauma may help augment repair processes.

Graft laceration and pullout strength of soft-tissue anterior cruciate ligament reconstruction: in vitro study comparing titanium, poly-d,l-lactide, and poly-d,l-lactide-tricalcium phosphate screws

PURPOSE

The aim of part 1 of this study was to compare the structural properties of tibia-graft-interference screw constructs of soft-tissue graft fixation via the anterior cruciate ligament (ACL) by use of different interference screws. In part 2 the influence of graft laceration as a result of 1 single interference screw insertion on the mechanical properties of the graft was evaluated.

METHODS

In part 1 of the study, in a bovine knee model, soft-tissue graft fixation with titanium, biodegradable poly-D,L-lactide (PLDLA), and PLDLA-tricalcium phosphate (TCP) interference screws was performed, and the structural properties were determined by use of a materials testing machine at a rate of 12.5 mm/s. In part 2 the bone was cut after 1 single insertion of titanium, PLDLA, or PLDLA-TCP interference screws, and the mechanical properties of the graft were determined.

RESULTS

Soft-tissue graft fixation with a biodegradable PLDLA interference screw showed a statistically significantly higher maximum load when compared with PLDLA-TCP and titanium interference screws. PLDLA-TCP screw fixation revealed a significantly higher ultimate load than titanium screw fixation. The mechanical properties of the grafts after 1 single insertion of PLDLA-TCP interference screws showed a statistically significantly higher stiffness, yield load, and maximum load when compared with the PLDLA and titanium interference screw groups.

CONCLUSIONS

The results of this study suggest that the use of a titanium screw to fix a soft-tissue graft in cruciate ligament reconstruction surgery may cause damage to the graft. Soft-tissue ACL reconstruction fixed with a PLDLA interference screw resulted in a significantly higher pullout strength than ACL reconstructions fixed with a PLDLA-TCP or titanium interference screw.

CLINICAL RELEVANCE

In contrast to fixation with a biodegradable interference screw, fixation with a titanium interference screw may damage the integrity of a soft-tissue graft in cruciate ligament reconstruction and should therefore be avoided.

Factors affecting return to sports after anterior cruciate ligament reconstruction with patellar tendon and hamstring graft: a prospective clinical investigation

In athletes, anterior cruciate ligament (ACL) reconstruction is recommended after injury to restore the normal knee function and allow subsequent return to sport. Successful ACL reconstruction with patellar tendon (PT) and hamstring tendon (HT) grafts combined with a well-structured rehabilitation program could bring athletes back to their previous level of sport activities. We prospectively followed-up 100 athletes who underwent ACL reconstruction with either PT (n=50) or HT grafts (n=50). Evaluation was done pre-operatively and post-operatively (3, 6, 12, and 24 months) using International Knee Documentation Committee (IKDC), Lysholm, Noyes, and Tegner scales. Subjective assessment numeric evaluation (SANE), knee activity rating scale (Marx) and a psychological profile questionnaire (psychovitality) were also utilized. Objective evaluations included isokinetic tests and computerized knee motion analysis. Data gathered were statistically analyzed using the Mann-Whitney non-parametric U-test. Among the 100 patients who have undergone ACL reconstruction, 65% returned to the same level of sports, 24% changed sports and 11% ceased sport activities. No significant difference (P>0.05) in outcome between PT and HT grafts were observed. No significant differences (P>0.05) were noted between athletes who "returned" to their previous sport and those who "did not return" to sports at the same level when using the IKDC, Lysholm, Noyes, and Tegner knee evaluation scales. However, significant difference was observed with the knee scores obtained by those who returned and those who completely ceased participation in sport activities. Computerized laxity test revealed that 90% of these patients have less than 3 mm side-to-side difference with no significant difference between HT and PT groups. Patients who "returned to sports" obtained significantly better scores with the Marx scale (P=0.001) and the psychovitality questionnaire (P=0.001) than those who did not. Conventional knee scales including IKDC, Lysholm, Noyes, and Tegner remain as reliable means of evaluating outcome of ACL reconstruction. However, the data obtained from these are not sufficient to determine which among the patients who had knee reconstruction can successfully return to sport. The use of the Marx knee activity rating scale and the evaluation of the athletes' psychological profile are additional scales that can be useful in determining which among the patients treated have a better chance of returning to their pre-injury activity levels.

ACL reconstruction and the implication of its tibial attachment for stability of the joint: anthropometric and biomechanical study

The planar topography of the anterior cruciate ligament (ACL) insertion was investigated and correlated to the use of the double-bundle/double tibial tunnel ACL reconstruction technique within the ACL tibial insertion area. The anteroposterior and mediolateral length of the tibial ACL attachment and the distances of the tibial insertion area from the anterior and posterior tibial borders were measured and the stability of the joint was tested using the double-bundle/double tibial tunnel ACL reconstruction technique. The anteroposterior length, 19.54 mm in men and 17.36 mm in women, of the ACL insertion, averaged approximately 40% of the total intercondylar anteroposterior dimension of the plateau. This broad distribution of insertion fibres ensures ligament tension and hence joint stability. The reported anteroposterior broad insertion of ACL fibres to the tibia is not sufficiently reproduced by the use of one or more bundles having a common tibial tunnel for the ACL reconstruction. In our view, this might be better achieved with two different bundles, with separate tunnels, and independent tensioning in different knee angles. This technique might achieve better results in human knee stability as opposed to other reported techniques.

Anterior cruciate ligament deficiency alters the in vivo motion of the tibiofemoral cartilage contact points in both the anteroposterior and mediolateral directions

BACKGROUND

Quantifying the effects of anterior cruciate ligament deficiency on joint biomechanics is critical in order to better understand the mechanisms of joint degeneration in anterior cruciate ligament-deficient knees and to improve the surgical treatment of anterior cruciate ligament injuries. We investigated the changes in position of the in vivo tibiofemoral articular cartilage contact points in anterior cruciate ligament-deficient and intact contralateral knees with use of a newly developed dual orthogonal fluoroscopic and magnetic resonance imaging technique.

METHODS

Nine patients with an anterior cruciate ligament rupture in one knee and a normal contralateral knee were recruited. Magnetic resonance images were acquired for both the intact and anterior cruciate ligament-deficient knees to construct computer knee models of the surfaces of the bone and cartilage. Each patient performed a single-leg weight-bearing lunge as images were recorded with use of a dual fluoroscopic system at full extension and at 15 degrees , 30 degrees , 60 degrees , and 90 degrees of flexion. The in vivo knee position at each flexion angle was then reproduced with use of the knee models and fluoroscopic images. The contact points were defined as the centroids of the areas of intersection of the tibial and femoral articular cartilage surfaces.

RESULTS

The contact points moved not only in the anteroposterior direction but also in the mediolateral direction in both the anterior cruciate ligament-deficient and intact knees. In the anteroposterior direction, the contact points in the medial compartment of the tibia were more posterior in the anterior cruciate ligament-deficient knees than in the intact knees at full extension and 15 degrees of flexion (p < 0.05). No significant differences were observed with regard to the anteroposterior motion of the contact points in the lateral compartment of the tibia. In the mediolateral direction, there was a significant lateral shift of the contact points in the medial compartment of the tibia toward the medial tibial spine between full extension and 60 degrees of flexion (p < 0.05). The contact points in the lateral compartment of the tibia shifted laterally, away from the lateral tibial spine, at 15 degrees and 30 degrees of flexion (p < 0.05).

CONCLUSIONS

In the presence of anterior cruciate ligament injury, the contact points shift both posteriorly and laterally on the surface of the tibial plateau. In the medial compartment, the contact points shift toward the medial tibial spine, a region where degeneration is observed in patients with chronic anterior cruciate ligament injuries.

Early aseptic loosening of a total knee arthroplasty due to Gore-Tex particle-induced osteolysis

Anterior cruciate ligament reconstruction with the use of synthetic graft material has been used as an alternative to biologic grafts. The use of these grafts has largely been abandoned in reconstruction of the anterior cruciate ligament because of mechanical failure of the graft and production of wear debris leading to synovitis and recurrent effusions. This article presents a case of early, extensive periprosthetic osteolysis around a total knee arthroplasty associated with wear debris from retained fragments of a Gore-Tex (WL Gore and associates, Inc, Flagstaff, Ariz) (polytetrafluoroethylene) anterior cruciate ligament graft.

Transverse femoral fixation in anterior cruciate ligament (ACL) reconstruction with hamstrings grafts: an anatomic study about the relationships between the transcondylar device and the posterolateral structures of the knee

Iatrogenic risks concerning femoral cross pin devices for anterior criciate ligament (ACL) reconstruction using hamstrings grafts have not been evaluated. The aim of the study was to state anatomic relationships between the epicondylar cross pin hole and the posterolateral attachments of the knee, and to settle safe zones and technical improvements for its use. It is a descriptive anatomical study. Dissections were performed and measurements taken on 20 (2x10) fresh frozen cadaveric knees after standard arthroscopic and femoral ACL reconstruction procedure using the Transfix cross pin femoral device (Arthrex, Naples, FL, USA). In group I, femoral tunnel was performed through the tibial tunnel. In group II, an anteromedial portal technique was used. Group I: no iatrogenic injury. The cross pin was at 36.5+/-2.8 mm (33-41) from the femoral inferior articular area, and at 12.3+/-3.2 mm (7-17) from the lateral collateral ligament (LCL) insertion. Group II: in a half cases, there was an injury of the LCL, close to its insertion. The cross pin was at an average of 5.6+/-5.4 mm (0-15) from the LCL, and significantly closer in group II than in group I (P<0.01). In group I, there is a high correlation between cross pin to LCL distance and knee flexion obtained to drill the femoral tunnel (r (2)=0.75, P<0.01). In conclusion, there is a specific iatrogenic risk of transverse femoral fixation using the anteromedial portal approach, whereas the transtibial approach seems to be safe. Nevertheless, it can decrease with a correct femoral tunnel depth and an operative knee flexion over 130 degrees , in order to move LCL insertion and posterior cortical wall away.

Reconstruction of the anterior cruciate ligament using bone-patellar tendon-bone graft with double biodegradable femoral pin fixation

The purpose of this study was to evaluate the early clinical outcomes of the bone-patellar tendon-bone (BPTB) anterior cruciate ligament (ACL) reconstruction using biodegradable cross pin fixation. The nature of this study is a prospective nonrandomized clinical outcome study. Thirty-five patients who underwent BPTB ACL reconstruction with a minimum of 2 years follow-up evaluation were included in the study. Thirty BPTB autografts and five BPTB allografts were fixed with two biodegradable 2.7 mm cross pins (Rigid Fix) on the femoral side. Clinical evaluation included International Knee Documentation Committee (IKDC), Lysholm and Tegner activity score, and Telos stress device measurements. The average Lysholm knee score was 94.7 (of 100). Twenty-four patients reported an excellent result. The other eight patients were in a good group. According to the IKDC scores, 23 (66%) patients reported normal function, 12 (34%) patients reported nearly normal function, and no (0%) patient reported abnormal or severely abnormal function. Telos stress device values were less than 3 mm of sagittal displacement in 28 patients and 5 mm in 7 patients. No patients complained that their knees gave way fully, even with moderate or strenuous activities. All of the patients have returned to their preinjury level of activity and athletic participation. Clinical results support this technique as a reliable alternative for patellar tendon fixation in ACL reconstruction.

Gender and limb differences in dynamic postural stability during landing

OBJECTIVE

To determine if gender and limb dominance affect dynamic postural stability and vertical ground reaction force data during jump landings. Secondary objective was to assess the reliability of the dynamic postural stability index (DPSI).

DESIGN

A mixed model (2 genderx2 limb) repeated measures design was used to determine the effects of gender and limb dominance on dynamic postural stability. Subjects were required to perform a two-legged jump to a height equivalent of 50% of their maximum vertical leap, land on a single-leg and balance for three seconds.

SETTING

Sports Medicine Research Laboratory.

PARTICIPANTS

Forty healthy subjects (20 men, 20 women) participated in this investigation.

MAIN OUTCOME MEASURES

The DPSI and its directional components quantified dynamic postural stability during a single-leg jump landing. Normalized vertical ground reaction force data quantified energy absorption.

RESULTS

DPSI values revealed that females had significantly different dynamic postural stability as compared to males in the vertical plane [T (78)=-4.2, P<0.01], and in the composite score (dynamic postural stability index) [T (78)=-6.3, P<0.01]. In addition, females had significantly higher peak vertical ground reaction forces [T (78)=-13, P=0.01] than males. The DPSI also showed excellent reliability (ICC=0.96), with a 95% confidence interval ranging from 0.94 to 0.97.

CONCLUSIONS

The results indicate that females have higher dynamic postural stability scores in the vertical direction as well as the composite score. This suggests that females used different dynamic postural stability strategies than males. There were no side-to-side dynamic postural stability differences between healthy contralateral limbs.

Effect of extraction protocols and epidermal growth factor on the cellular repopulation of decellularized anterior cruciate ligament allografts

We are developing a decellularized bone-anterior cruciate ligament (ACL)-bone allograft for treatment of ACL disruption in young or active patients. This study demonstrates the feasibility of seeding decellularized ACL tissue with primary ligament fibroblasts. Porcine ACLs were decellularized by one of three protocols, each differing only by the detergent/solvent used during the second wash (SDS, Triton-X, or TnBP). Porcine ACL fibroblasts were obtained by explant and seeded onto tissue samples of decellularized ACL. Culture conditions were varied to compare the relative effect of three different decellularization protocols on cellular repopulation. Culture condition variables included (1) the number of cells used for seeding, (2) the addition of epidermal growth factor (EGF), and (3) culture duration. Cellular ingrowth was assessed by metabolic activity (MTT assay), DNA quantification (Hoescht dye), and histology (H&E staining). Cell counting on histological sections demonstrated that Triton-X-and TnBP-treated ligaments were more receptive to cellular ingrowth than SDS-treated samples. The addition of EGF to culture medium did not significantly increase cellular ingrowth. Both the Triton-X and TnBP decellularization treatments provide suitable, naturally derived scaffolds for the ingrowth of primary ACL fibroblasts, and should be further investigated in the development of an allograft-derived bone-ACL-bone graft.

Influence of the tunnel angle in ACL reconstructions on the biomechanics of the knee joint

BACKGROUND

A high tension in anterior cruciate ligament grafts affects both graft and knee functional performance. Clinical observations suggest that impingement of the graft against the posterior cruciate ligament might cause high graft tensions. Also, meniscal injury has been well documented in association with damage in the anterior cruciate ligament.

METHODS

In this paper, we present the results obtained in a three-dimensional finite element model of the human knee, corresponding to different aspects of anterior cruciate ligament reconstruction with bone-patellar tendon-bone grafts. This model was used to investigate the effect of the angle in the coronal plane of femoral and tibial tunnels. Firstly, graft tension was computed in a knee moved from 0 degrees to 60 degrees of flexion and the results were compared with experimental ones obtained by other authors. Secondly, the resulting kinematics under an anterior load of 134 N was compared to that of the intact knee.

FINDINGS

The obtained results showed that the closest anterior tibial translation to that of the intact knee was obtained with femoral and tibial tunnels with angles of 60 degrees. In this same case, a lower graft tension was also obtained. The results demonstrated noticeable increases in the meniscal stresses after anterior cruciate ligament reconstruction.

INTERPRETATION

Our results showed that impingement only depends on the femoral tunnel angle. On the contrary, laxity principally depends on the tibial tunnel angle. The angle of the femoral tunnel affects the graft tension while the tibial tunnel affects laxity, meniscal stresses and strains.

[The influence of a controlled active motion splint on proprioception after anterior cruciate ligament plasty. A prospective randomized study]

BACKGROUND

A ruptured anterior cruciate ligament (ACL) leads to both mechanical and functional instability. Functional instability is caused by proprioceptive deficit. The aim of this study was to determine whether the proprioceptive deficit can be reduced by using a controlled active motion (CAM) splint postoperatively.

PATIENTS AND METHODS

A total of 50 patients with ACL rupture were randomized into two groups. After ACL plasty the PT group received postoperative physiotherapy, while the CAM group were managed with a CAM splint and physiotherapy. Proprioceptive ability was measured with a passive angle-reproduction test.

RESULTS

On the day of discharge 80% of the patients in the CAM group and 25% in the PT group had a reduced proprioceptive deficit. Overall the main measured value in the CAM group improved by 83.7%, but deteriorated by 39.3% in the PT group. There was no significant difference between the CAM group and a healthy control group.

CONCLUSION

Using a CAM splint in addition to physiotherapy after ACL plasty in comparison to physiotherapy alone decreases the proprioceptive deficit significantly. We recommend the use of a CAM splint in the postoperative management following ACL plasty.

Arthroscopic single-stranded semitendinosus tendon- versus PDS-augmentation of reinserted acute femoral anterior cruciate ligament tears: 7 year follow-up study

This study reviews the long-term results of acute complete femoral tears or combined femoral (2/3 of the ligament diameter) /interstitial tears of the anterior cruciate ligament (ACL) that were reinserted. Out of 27 patients, 11 were treated with reinsertion plus augmentation with single-stranded semitendinosus tendon, 16 patients had a reinsertion and augmentation with a double-stranded PDS-band. Operation was carried out 10 (2-42) days after trauma. A brace was applied for 12 weeks, full weight bearing was allowed after 6 weeks according to our standard rehabilitation protocol. Twenty two patients (81%) could be reevaluated after a mean follow-up time of 7 years 1 month (range 3 years 8 months -11 years 5 months). No statistically significant difference was found between both techniques concerning patient's satisfaction and subjective evaluation of knee function, OAK-scores (semitendinosus-augmentation: 96 point, SD 2.0 PDS-augmentation: 94 points, SD 5.1) and IKDC-scores. Only in the PDS-augmentation group a statistically significant decrease was found in the level of activity in sports (P=0.046). At follow-up, radiological evaluation of the anterior drawer test was performed. In the group of patients who had undergone semitendinosus augmentation (n=9), anterior displacement of the tibia (determined radiologically using the TELOS-device) of 0-2 mm was found in five patients, displacement of 3-5 mm was seen in three cases and displacement of 6-10 mm in one patient (average 2.7 mm). Patients treated with PDS-augmentation (n=13) showed anterior tibial displacement of 0-2 mm in five cases, 3-5 mm in five cases, and 6-10 mm in two knees (average 3.6 mm). One patient of this group underwent ACL-reconstruction 6 years after reinsertion because of recurrent instability. At follow up, flexion was limited to less than 135 degrees in three patients (12.5%). One patient who had undergone semitendinosus augmentation and three patients from the PDS-augmentation group developed a cyclops syndrome and intraarticular adhesions that were treated arthroscopically 6 to 18 month after reinsertion surgery. A tendency towards a higher rate of limitation in range of motion was found for the PDS augmentation group. The reinsertion of a femoral torn ACL plus augmentation with a single strand of semitendinosus tendon or a PDS-band leads to acceptable results, an aggressive rehabilitation protocol may help to decrease the rate of limitation of flexion.

Tissue engineering for anterior cruciate ligament reconstruction: a review of current strategies

The anterior cruciate ligament (ACL) is one the most commonly injured ligaments of the knee. Chronic ACL insufficiency can result in episodic instability, chondral and meniscal injury, and early osteoarthritis. The intra-articular environment of the ligament precludes normal healing and surgical replacement of the injured ligament is often mandated to restore stability. Current surgical strategies include the use of local autograft or allograft tissues for ligament reconstruction. These procedures have yielded superior long-term clinical results yet have the potential for serious associated morbidities. Existing limitations have prompted ongoing research designed to engineer a replacement ligament that will parallel the native ACL in both its biologic properties and mechanical durability. Ligament engineering necessitates the use of appropriate source cells and a growth matrix to support cell proliferation and collagen synthesis. The identification of appropriate growth modulators including both biochemical factors and mechanical stimuli are requisites for successful tissue growth. The characterization of the elements essential for successful graft development represents a significant challenge for investigators. This review examines the current literature regarding the potential and limitations of ligament engineering and describes the development of a novel 3-dimensional scaffold and bioreactor system at our institution.

Decrease of knee flexion torque in patients with ACL reconstruction: combined analysis of the architecture and function of the knee flexor muscles

A decrease of deep knee flexion torque after anterior cruciate ligament (ACL) reconstruction, using a semitendinosus (and gracilis) tendon, has been reported. However, the cause of this weakness remains controversial. Architectural and functional differences in the knee flexor muscles influence this weakness. the fiber length of the semitendinosus, gracilis, semimembranosus, and biceps femoris were directly measured in six human cadavers. The flexion torque and EMG of the hamstrings were measured in both limbs of 16 patients (23+/-5 years) after ACL reconstruction (12-43 months post-operation), using ipsilateral semitendinosus tendon. Magnetic resonance imagings were taken, over both the thighs of those patients, to measure muscle volume and to confirm a state of semitendinosus tendon regeneration. The position of the musculotendinous junction of the semitendinosus was also analyzed. The fiber length of the semitendinosus and gracilis were three to four times longer than that of the semimembranosus and biceps femoris. The difference of flexion torque between the normal and ACL reconstructed limbs significantly increased as the knee flexion angle increased. The EMG value for the semimembranosus and biceps femoris of both limbs as well as the semitendinosus of the ACL reconstructed limbs, significantly reduced as the knee flexion angle was increased. The volume of the semitendinosus in the reconstructed limb was significantly smaller than in normal limbs. The regeneration of the semitendinosus tendon was confirmed in all subjects, and the musculotendinous junction position of the reconstructed limb in almost all subjects was found in further image from the knee joint space than that for the normal limb. The decrease of deep knee flexion torque, after ACL reconstruction, could be due to the atrophy and shortening of the semitendinosus after its tendon has been harvested, as well as the lack of compensation from the semimembranosus and biceps femoris, due to the architectural differences between the semitendinosus and the semimembranosus and biceps femoris.

Anterior cruciate ligament injuries in female athletes: Part 2, a meta-analysis of neuromuscular interventions aimed at injury prevention

Female athletes have a 4 to 6 times higher incidence of anterior cruciate ligament injury than do male athletes participating in the same landing and pivoting sports. This greater risk of anterior cruciate ligament injury, coupled with a geometric increase in participation (doubling each decade), has led to a significant rise in anterior cruciate ligament injuries in female athletes. The gender gap in anterior cruciate ligament injury, combined with evidence that the underpinnings of this serious health problem are neuromuscular in nature, leads to the development of neuromuscular interventions designed to prevent injury. A systematic review of the published literature yielded 6 published interventions targeted toward anterior cruciate ligament injury prevention in female athletes. Four of 6 significantly reduced knee injury incidence, and 3 of 6 significantly reduced anterior cruciate ligament injury incidence in female athletes. A meta-analysis of these 6 studies demonstrates a significant effect of neuromuscular training programs on anterior cruciate ligament injury incidence in female athletes (test for overall effect, Z = 4.31, P < .0001). Examination of the similarities and differences between the training regimens gives insight into the development of more effective and efficient interventions. The purpose of this "Current Concepts" review is to highlight the relative effectiveness of these interventions in reducing anterior cruciate ligament injury rates and to evaluate the common training components between the training studies. In addition, the level of rigor of these interventions, the costs and the difficulty of implementation, the compliance with these interventions, and the performance benefits are discussed. This review summarizes conclusions based on evidence from the common components of the various interventions to discuss their potential to reduce anterior cruciate ligament injury risk and assess their potential for combined use in more effective and efficient intervention protocols.

Knee isometric torque and electromyographic specificities after semitendinosus and gracilis hamstrings anterior cruciate ligament reconstruction

OBJECTIVES

Because the co-contraction of the gastrocnemius and hamstring muscles strains the anterior cruciate ligament, the role of the gastrocnemius muscle is of particular importance after semitendinosus and gracilis tendon autografts for anterior cruciate ligament reconstruction. This study aimed to examine the neuromuscular mechanisms underlying postsurgical torque deficits during knee flexion by using surface electromyography.

DESIGN

A total of 14 volunteer patients (eight men, six women; age, 32.5 +/- 9.3 yrs; height, 172.7 +/- 6 cm; weight, 69.6 +/- 10.2 kg) were enrolled in the study; all had undergone anterior cruciate ligament reconstruction performed by the same surgeon. The neuromuscular mechanisms were assessed using isometric tests and surface electromyographic recordings at 19 mos post-reconstruction. The torque deficits in the injured knee were compared with the uninjured knee, which served as control values.

RESULTS

Significant differences in torque production were observed between the two limbs at specific angular positions during the extension and flexion tests (P < 0.05). The difference in the root mean square myoelectrical activity between the limbs was computed at each tested position, revealing that the gastrocnemius muscle had greater activity at 75 degrees than at 45 degrees (P < 0.05).

CONCLUSIONS

In deep flexion (>70 degrees), the gastrocnemius muscle may compensate for the weakened hamstrings and thereby strain the anterior cruciate ligament graft after anterior cruciate ligament semitendinosus and gracilis tendon reconstruction.

Measurement and Evaluation of Dynamic Joint Stability of the Knee and Ankle After Injury

Injuries to the lower extremity, specifically the knee and ankle joints of the human body can occur in any athletic event and are most prevalent in sports requiring cutting and jumping manoeuvres. These joints are forced to rely on the dynamic restraints to maintain joint stability, due to the lack of bony congruence and the inability of the static restraints to handle the forces generated during functional tasks. Numerous variables (proprioception, postural control, electromyography, kinetics/kinematics, dynamic stability protocols) have been measured to better understand how the body maintains joint stability during a wide range of activities from static standing to dynamic cutting or landing from a jump. While the importance of dynamic restraints is not questioned, a recent impetus to conduct more functional or sport-specific testing has emerged and placed a great deal of emphasis on dynamic joint stability and how it is affected by lower extremity injuries. Evidence suggests that surgery and aggressive rehabilitation will not necessarily restore the deficits in dynamic joint stability caused by injury to the anterior cruciate ligament or lateral ankle ligaments. In today's athletic society, there is a major push to return athletes to play as quickly as possible. However, the ramifications of those decisions have not been fully grasped. If an athlete is not fully recovered, a quick return to play could start a vicious cycle of chronic injuries or permanent disability.

Joint laxity and isokinetic thigh muscle strength characteristics after anterior cruciate ligament reconstruction: bone patellar tendon bone versus quadrupled hamstring autografts

OBJECTIVES

To analyze ligamentous stability and isokinetic strength of knee extensor and flexor muscles after anterior cruciate ligament reconstruction using 2 different autografts with identical fixation.

DESIGN

This study implements a comparative case series design.

SETTING

Schulthess Clinic, Switzerland.

PATIENTS

A total of 153 consecutive patients (n = 87 bone-patellar tendon-bone [BPTB]/66 quadruple semitendinosus/gracilis tendons [QSGT] patients) who underwent BPTB and QSGT surgery were functionally assessed.

INTERVENTION

All patients were functionally assessed (knee extension/flexion isokinetic strength and knee joint laxity) at a mean follow-up time of 11 months.

MAIN OUTCOME MEASUREMENTS

Laxity was measured utilizing the Kneelax arthrometer, whereas isokinetic strength of the knee extensor/flexor muscle groups was measured using the Biodex Multi Joint System 2 (180 degrees/s and 300 degrees/s).

RESULTS

The QSGT group had significantly greater knee joint laxity when compared with the BPTB group (P < 0.001). Furthermore, females in the QSGT group demonstrated the greatest knee joint laxity overall (P < 0.001). Additionally, a significant flexor torque deficiency was demonstrated in the QSGT group (P < 0.001); however, no differences in extensor torque were observed.

CONCLUSIONS

The use of a BPTB autograft achieved better knee joint stability as well as greater knee flexor torque than the QSGT autograft. Both grafts exhibited a similar knee extensor torque deficit, indicating that only quadriceps strength is not graft-dependent.

[Observations of normal and ACL-deficient knee joints after stress MRI]

BACKGROUND

The Lachman test is the most reliable clinical test for diagnosing rupture of the anterior cruciate ligament (ACL). Previous X-ray studies have presented a "radiologic Lachman test". Recently anterior tibial translation was demonstrated using open access MRI. Two methods were developed to transfer a similar technique to a more widely available closed MRI.

METHODS

Using closed MRI we investigated 22 knees in 21 patients with pure rupture of the ACL. Anteriorly and posteriorly directed shear forces were applied to the tibiofemoral joint at 20 degrees flexion either by positioning a 9-kg load on the distal femur (method 1) or performing a semi-manual Lachman test with a custom-made orthosis (method 2).

RESULTS

Both methods produced relative anterior tibial translation in both compartments of the normal and ACL-deficient knee which could be measured on sagittal images. They were greater laterally than medially and in injured than in uninjured knees. However, instability of the medial compartment predicted clinical and symptomatic instability as translation was posterior to positions achieved in normal knees during the active and passive flexion arc.

CONCLUSION

A Lachman sign can be produced in a closed magnet with different methods and findings can be used for more precise information regarding kinematics and degree of instability and could be helpful if surgical treatment is necessary.

Effectiveness of three extraction techniques in the development of a decellularized bone–anterior cruciate ligament–bone graft

In this study, porcine bone-anterior cruciate ligament-bone (B-ACL-B) grafts were decellularized using one of three protocols incorporating surfactants lauryl sulfate (SDS), Triton X-100, and/or an organic solvent (tributyl phosphate (TnBP)). The effectiveness of Triton-SDS, Triton-Triton or Triton-TnBP treatments in removing cellular materials was determined and possible changes in biochemical composition and mechanical properties due to each treatment were investigated. Treatment with Triton-SDS was most effective at removing cell nuclei and intracellular protein (vimentin) from the ACL but affected both the collagen and glycosaminoglycan (GAG) components of the extracellular matrix while increasing the tensile stiffness of the ligament. Triton-Triton was the least effective of the three treatments in terms of cellular extraction, but did not significantly change the mechanical and biochemical properties of the ACL. Triton-TnBP matched the level of decellularization achieved by Triton-SDS in terms of visible cell nuclei; however, the extraction of intracellular vimentin was less consistent. TnBP treatment also slightly decreased the collagen content of the ACL but did not alter its mechanical properties. Overall, all three decellularization treatments maintained adequate mechanical and biochemical properties of B-ACL-B grafts to justify the further investigation of all three decellularization protocols. The selection of a superior treatment will depend on future studies of the propensity of treated tissues for repopulation by host ACL fibroblasts and, ultimately, on any immunogenic and/or remodeling host response induced in vivo.

Treatment of anterior cruciate ligament injuries, part 2

Anterior cruciate ligament tears, common among athletes, are functionally disabling; they predispose the knee to subsequent injuries and the early onset of osteoarthritis. A total of 3810 studies published between January 1994 and the present were identified and reviewed to determine the current state of knowledge regarding the treatment of anterior cruciate ligament injuries. Part 1 of this article focused on studies pertaining to the biomechanical behavior of the anterior cruciate ligament, the prevalence of and risk factors for injuries related to it, the natural history of the ligament-deficient knee, injuries associated with anterior cruciate ligament disruption, indications for the treatment of anterior cruciate ligament injuries, as well as nonoperative and operative treatments. Part 2 includes technical aspects of anterior cruciate ligament surgery, bone tunnel widening, graft healing, rehabilitation after anterior cruciate ligament reconstruction, and the effects of sex, age, and activity level on the outcome of such reconstructive surgery.

Association between lower extremity posture at contact and peak knee valgus moment during sidestepping: implications for ACL injury

BACKGROUND

Knee valgus load during sports movement is viewed as an important predictor of non-contact anterior cruciate ligament injury risk, particularly in females. Formulating movement strategies that can reduce valgus loading during these movements therefore appears pertinent to reducing anterior cruciate ligament injury rates. With this in mind, the current study examined the relationship between peak valgus moment and lower extremity postures at impact during a sidestep cutting task.

METHODS

Ten male and ten female NCAA athletes had initial contact three-dimensional hip, knee and ankle angles and subsequent knee valgus moment quantified during the execution of (n=10 trials) sidesteps. Peak valgus data were normalized to mass and height and tested for the main effect of gender (ANOVA, P<0.05). Intra-subject correlations between the eight initial joint angles and the normalized valgus moment were then conducted across the ten sidestepping trials. The ensuing slopes of regression were submitted to a two-sample t-test to determine whether mean slope values were significantly different from zero and for the main effect of gender (P<0.05).

FINDINGS

Females had significantly larger normalized knee valgus moments than males. A greater peak valgus moment was associated with larger initial hip flexion and internal rotation, and with larger initial knee valgus angle. Peak knee valgus moment was more sensitive to initial hip internal rotation and knee valgus position in females.

INTERPRETATION

Training of neuromuscular control at the hip joint may reduce the likelihood of anterior cruciate ligament injury via a valgus loading mechanism during sidestepping, especially in females.