Evaluation of the Failed ACL Reconstruction

The Role of High Tibial Osteotomy in ACL Reconstruction in Knees with Coronal and Sagittal Plane Deformity

PURPOSE OF REVIEW

Coronal and sagittal malalignment in the setting of anterior cruciate ligament (ACL) deficiency alters knee biomechanics and is shown to increase stress and strain on the native ACL and on the ACL graft during reconstruction. The purpose of this review was to determine the role and indications of high tibial osteotomy to correct coronal and/or sagittal plane malalignment with ACL reconstruction.

RECENT FINDINGS

Recent literature illustrates that an increase in varus malalignment and increased posterior tibial slope increases the biomechanical stress that is seen in a native or reconstructed ACL graft. It has been proposed to correct the sagittal and coronal malalignment by employing a high tibial osteotomy either prior to or at the time of ACL reconstruction to correct these deformities and to decrease the stress placed on the reconstructed ACL graft. The use of high tibial osteotomy for deformity correction creates a more stable knee for ACL reconstruction and has been shown to have good outcomes with regard to post-operative pain, stability, satisfaction scores, and function.

Using an accelerometer and the step-up-and-over test to evaluate the knee function of patients with anterior cruciate ligament reconstruction

BACKGROUND

Evaluating the dynamic knee function of patients after anterior cruciate ligament reconstruction is a challenge. A variety of objective tests have been developed but for various reasons few are regularly used in the clinic. It may be practical to perform the step-up-and-over test with an accelerometer.

METHODS

A control group (N=26) and an experimental group with a reconstructed anterior cruciate ligament (N=25) completed questionnaires quantifying subjective knee function and fear of re-injury and then completed the step-up-and-over test.

FINDINGS

Results showed that the experimental group performed differently than the control group for the step-up-and-over test's Lift Symmetry and Impact Symmetry (P<0.05) and performance on these measures was related to the participant's subjective knee function (ρ=-0.46, P<0.01; ρ=-0.33, P<0.05, respectively). Supplemental results for individual leg performance and the patient's fear of re-injury are also reported and discussed.

INTERPRETATION

Performance on the step-up-and-over test is different for participants with anterior cruciate ligament reconstruction than for those with intact anterior cruciate ligaments, and that performance is related to one's opinion of their knee's function.

Imaging ACL reconstructions and their complications

Examination of ligament reconstructions, particularly of the anterior cruciate ligament (ACL), are common situations in everyday knee imaging practice. Knowledge of normal appearances, the expected changes over time and the potential complications of these plasties are essential. MRI is the imaging method of choice. This article illustrates the main complications specific to this procedure: suboptimal positioning of the femoral or tibial tunnels, impingement between the graft and bony contours, rupture (partial or complete) of the plasty due to friction or injury, arthrofibrosis and particularly the "Cyclops" syndrome, fragmentation or migration of the fixation materials and a granulomatous reaction to biomaterials.

Close-looped graft suturing improves mechanical properties of interference screw fixation in ACL reconstruction

PURPOSE

In anterior cruciate ligament reconstruction with looped soft-tissue grafts, an interference screw is frequently used for tibial fixation. This study compared three alternatives thought to improve the initial mechanical properties of direct bioabsorbable interference screw fixation: suturing the graft to close the loop, adding a supplementary staple, or increasing the oversize of the screw diameter relative to the bone tunnel from 1 to 2 mm.

METHODS

Twenty-eight porcine tibiae and porcine flexor digitorum profundus tendons were randomized into four testing groups: a base fixation using 10-mm-diameter screw with open-looped graft, base fixation supplemented by an extracortical staple, base fixation but closing the looped graft by suturing its ends, and base fixation but using an 11-mm screw. Graft and bone tunnel diameters were 9 mm in all specimens. Constructs were subjected to cyclic tensile load and finally pulled to failure to determine their structural properties.

RESULTS

The main mode of failure in all groups was pull-out of tendon strands after slippage past the screw. The sutured graft group displayed significantly lower residual displacement (mean value reduction: 47-67 %) and higher yield load (mean value increase: 38-54 %) than any alternative tested. No other statistical differences were found.

CONCLUSIONS

Suturing a soft-tissue graft to form a closed loop enhanced the initial mechanical properties of tibial fixation with a bioabsorbable interference screw in anterior cruciate ligament reconstructions using a porcine model, and thus, this may be an efficient means to help in reducing post-operative laxity and early clinical failure. No mechanical improvement was observed for an open-looped tendon graft by adding an extracortical staple to supplement the screw fixation or by increasing the oversize of the screw to tunnel diameter from 1 to 2 mm.

Anterior cruciate ligament fixation: is radial force a predictor of the pullout strength of soft-tissue interference devices?

BACKGROUND

In anterior cruciate ligament (ACL) reconstruction, an interference device achieves soft-tissue graft fixation by radially compressing the graft against the bone.

PURPOSE

The objective of this study was to measure the radial force generated by different interference devices and evaluate the effect of this radial force on the pullout strength of graft-device constructs.

STUDY DESIGN

Controlled laboratory study.

METHODS

A resultant force (F(R)) was used as a representative measure of the total radial force generated. Bovine tendons were fixated in either synthetic bone or porcine tibia using one of following devices: (1) RCI titanium screw, (2) PEEK screw, (3) IntraFix sheath-and-screw device, and (4) ExoShape sheath-and-insert device. F(R) was measured while each device was inserted into synthetic bone mounted on a test machine (n=5 for each device). In a subsequent test series, graft-device constructs were loaded to failure at 50mm/min. The pullout strength was measured as the ultimate load before failure (n=10 for each device).

RESULTS

The F(R) values generated during insertion into synthetic bone were 777 ± 86N, 865 ± 140N, 1313 ± 198N, and 1780 ± 255N for the RCI screw, PEEK screw, IntraFix, and ExoShape, respectively. The pullout strengths in synthetic bone for the RCI screw, PEEK screw, IntraFix and ExoShape were 883 ± 125N, 716 ± 249N, 1147 ± 142N, and 1233 ± 190N, respectively.

CONCLUSIONS

These results suggest that the F(R) generated during interference fixation affects the pullout strength with sheath-based devices providing superior F(R) compared with interference screws. The use of synthetic bone was validated by comparing the pullout strengths to those when tested in porcine tibia.

CLINICAL RELEVANCE

These results could be valuable to a surgeon when determining the best fixation device to use in the clinical setting.

MR in the evaluation of new anterior cruciate ligament and tibial tunnel position: correlation with clinical and functional features

PURPOSE

This study aimed to evaluate correlations between the position of the tibial tunnel, its alignment with the ligament-screw system, presence of intratunnel fluid, position of the tibial tunnel with respect to the Blumensaat line and clinical knee stability in patients who underwent arthroscopic reconstruction of the anterior cruciate ligament (ACL), by using magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Forty-eight patients (40 men, eight women; mean age, 31 years) underwent arthroscopic reconstruction of the ACL using double-strand semitendinosus and gracilis tendons. The new ACL was fixed to the tibial tunnel using Bio-Intrafix (Mitek). All patients underwent MR imaging 12 months after surgery and clinical evaluation at 6 and 12 months using the International Knee Documentation Committee (IKDC) scoring system. MR imaging and clinical features were correlated using the Mann-Whitney U test for continuous variables and Fisher's exact test for categorical variables.

RESULTS

Forty-one patients were clinically stable (groups A and B according to the IKDC test) and seven were unstable (group C). Mean values of tibial tunnel position in clinically unstable vs stable patients were, respectively, -3.6 ±3.8 mm vs. -2.8±3.8 mm in relation to the Blumensaat line (p=0.5712) and 77.3°±11.3 vs. 72.5°±5.5 as concerned the angle measured on the coronal view of the new ACL (p=0.3248); fluid was present in the tibial tunnel in 42.9% and 9.8% of cases, respectively (p=0.2104). MR imaging showed misalignment of ligament screw and tibial tunnel in 57.1% of patients in group C and in 12.2% in groups A and B (p=0.017).

CONCLUSIONS

Misalignment of the ligament-screw system and the tibial tunnel and the presence of fluid in the tibial tunnel appear to be directly correlated with clinical instability.

Evidence-based rehabilitation following anterior cruciate ligament reconstruction

Following a bone-patellar tendon-bone autograft (BPTB) or four-stranded semitendinosus/gracilis tendons autograft (ST/G) anterior cruciate ligament (ACL) reconstruction, the speed and safety with which an athlete returns to sports (or regains the pre-injury level of function) depends on the rehabilitation protocol. Considering the large differences in clinical and outpatient protocols, there is no consensus regarding the content of such a rehabilitation program. Therefore, we conducted a systematic review to develop an optimal evidence-based rehabilitation protocol to enable unambiguous, practical and useful treatment after ACL reconstruction. The systematic literature search identified 1,096 citations published between January 1995 and December 2006. Thirty-two soundly based rehabilitation programs, randomized clinical trials (RCT's) and reviews were included in which common physical therapy modalities (instruction, bracing, cryotherapy, joint mobility training, muscle-strength training, gait re-education, training of neuromuscular function/balance and proprioception) or rehabilitation programs were evaluated following ACL reconstruction with a BPTB or ST/G graft. Two reviews were excluded because of poor quality. Finally, the extracted data were combined with information from background literature to develop an optimal evidence-based rehabilitation protocol. The results clearly indicated that an accelerated protocol without postoperative bracing, in which reduction of pain, swelling and inflammation, regaining range of motion, strength and neuromuscular control are the most important aims, has important advantages and does not lead to stability problems. Preclinical sessions, clear starting times and control of the rehabilitation aims with objective and subjective tests facilitate an uncomplicated rehabilitation course. Consensus about this evidence-based accelerated protocol will not only enhance the speed and safety with which an athlete returns to sports, but a standardized method of outcome measurement and reporting will also increase the evidential value of future articles.

Supplemental tibial fixation for anterior cruciate ligament reconstruction

This report describes transosseous backup suture fixation for anterior cruciate ligament (ACL) grafts of all varieties, used to distally augment proximal screw fixation in the tibia. Using a simple suture configuration, this method secures the ACL graft to the tibial cortex in conjunction with a proximal interference screw. The technique is applicable for all graft configurations, including allograft, autograft, bone, and both 2- and 4-strand soft-tissue grafts. The described technique is intended to be used for secondary or backup fixation of the graft in the tibial tunnel and not as primary fixation. This construct can be reproducibly created, making use of the sutures that are typically present on the graft after the interference screw is placed. This technique for backup tibial fixation precludes the need for external hardware, which in many instances may be symptomatically proud. Furthermore, use of this technique may represent a potential cost savings because no additional devices or equipment is used or purchased. This technique is simple, fast, and inexpensive, making use of available constructs to enhance the security of graft fixation during ACL reconstruction.