Revision anterior cruciate ligament surgery

Hybrid Graft Anterior Cruciate Ligament Reconstruction: A Predictable Graft for Knee Stabilization

Trauma to the anterior cruciate ligament (ACL) is a season-ending injury and involves months of activity modification and rehabilitation. The annual incidence of ACL tears in the United States is approximately 200,000, which allows for a broad range of individualized treatment options. Various surgical techniques, including transtibial and independent tunnel drilling, allograft and autograft tissue, and various implants, have been described in the literature. This article describes the indications and technique for a hybrid soft tissue graft for ACL reconstruction. Autologous grafts eliminate the risk of disease transmission and have recently been shown to have a lower rerupture rate, particularly in younger, active patients; however, the harvesting of autologous hamstring grafts carries a risk of donor-site morbidity, iatrogenic injury of the graft, and inadequate graft size. In contrast to a traditional autologous soft tissue graft, the hybrid graft allows for graft size customization for a desired reconstruction, especially in cases where autograft hamstrings may be iatrogenically damaged or of inadequate size when harvested. The goal of a hybrid graft ACL reconstruction is to provide a favorable-sized graft with clinical outcomes comparable with autologous soft tissue grafts. In contrast to a traditional autologous soft tissue graft, this technique provides another option in the event of unforeseen deficiencies or complications associated with harvesting and preparation of the autologous gracilis and semitendinosis soft tissue graft.

Multirater agreement of the causes of anterior cruciate ligament reconstruction failure: a radiographic and video analysis of the MARS cohort

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction failure occurs in up to 10% of cases. Technical errors are considered the most common cause of graft failure despite the absence of validated studies. Limited data are available regarding the agreement among orthopaedic surgeons regarding the causes of primary ACL reconstruction failure and accuracy of graft tunnel placement.

HYPOTHESIS

Experienced knee surgeons have a high level of interobserver reliability in the agreement about the causes of primary ACL reconstruction failure, anatomic graft characteristics, and tunnel placement.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

Twenty cases of revision ACL reconstruction were randomly selected from the Multicenter ACL Revision Study (MARS) database. Each case included the patient's history, standardized radiographs, and a concise 30-second arthroscopic video taken at the time of revision demonstrating the graft remnant and location of the tunnel apertures. All 20 cases were reviewed by 10 MARS surgeons not involved with the primary surgery. Each surgeon completed a 2-part questionnaire dealing with each surgeon's training and practice, as well as the placement of the femoral and tibial tunnels, condition of the primary graft, and the surgeon's opinion as to the causes of graft failure. Interrater agreement was determined for each question with the kappa coefficient and the prevalence-adjusted, bias-adjusted kappa (PABAK).

RESULTS

The 10 reviewers have been in practice an average of 14 years and have performed at least 25 ACL reconstructions per year, and 9 were fellowship trained in sports medicine. There was wide variability in agreement among knee experts as to the specific causes of ACL graft failure. When participants were specifically asked about technical error as the cause for failure, interobserver agreement was only slight (PABAK = 0.26). There was fair overall agreement on ideal femoral tunnel placement (PABAK = 0.55) but only slight agreement on whether a femoral tunnel was too anterior (PABAK = 0.24) and fair agreement on whether it was too vertical (PABAK = 0.46). There was poor overall agreement for ideal tibial tunnel placement (PABAK = 0.17).

CONCLUSION

This study suggests that more objective criteria are needed to accurately determine the causes of primary ACL graft failure as well as the ideal femoral and tibial tunnel placement in patients undergoing revision ACL reconstruction.

Electrospun fibre diameter, not alignment, affects mesenchymal stem cell differentiation into the tendon/ligament lineage

Efforts to develop engineered tendons and ligaments have focused on the use of a biomaterial scaffold and a stem cell source. However, the ideal scaffold microenvironment to promote stem cell differentiation and development of organized extracellular matrix is unknown. Through electrospinning, fibre scaffolds can be designed with tailorable architectures to mimic the intended tissue. In this study, the effects of fibre diameter and orientation were examined by electrospinning thin mats, consisting of small (< 1 µm), medium (1-2 µm) or large (> 2 µm) diameter fibres with either random or aligned fibre orientation. C3H10T1/2 model stem cells were cultured on the six different electrospun mats, as well as smooth spin-coated films, and the morphology, growth and expression of tendon/ligament genes were evaluated. The results demonstrated that fibre diameter affects cellular behaviour more significantly than fibre alignment. Initially, cell density was greater on the small fibre diameter mats, but similar cell densities were found on all mats after an additional week in culture. After 2 weeks, gene expression of collagen 1α1 and decorin was increased on all mats compared to films. Expression of the tendon/ligament transcription factor scleraxis was suppressed on all electrospun mats relative to spin-coated films, but expression on the large-diameter fibre mats was consistently greater than on the medium-diameter fibre mats. These results suggest that larger-diameter fibres (e.g. > 2 µm) may be more suitable for in vitro development of a tendon/ligament tissue.

Notchplasty in anterior cruciate ligament reconstruction in the setting of passive anterior tibial subluxation

PURPOSE

In an effort to minimize graft impingement among various ACL deficient states, we sought to quantitatively determine requirements for bone resection during notchplasty with respect to both volumetric amount and location.

METHODS

A validated method was used to evaluate Magnetic Resonance Imaging scans. We measured the ATT of the medial and lateral compartments in the following four states: intact ACL (27 patients), acute ACL disruption; <2 months post-injury (76 patients), chronic ACL disruption; 12 months post-injury (42 patients) and failed ACL reconstruction (75 patients). Subsequently, 11 cadaveric knees underwent Computed Tomography (CT) scanning. Specialized software allowed virtual anterior translation of the tibia according to the average ATT measured on MRI. Impingement volume was analyzed by performing virtual ACLRs onto the various associated CT scans. Location was analyzed by overlaying an on-screen protractor. The center of the notch was defined as 0°.

RESULTS

Average impingement volume changed significantly in the various groups compared to the intact ACL group (acute 577 ± 200 mm(3), chronic 615 ± 199 mm(3), failed ACLR 678 ± 210 mm(3), p=0.0001). The location of the required notchplasty of the distal femoral wall border did not change significantly. The proximal femoral border moved significantly towards the center of the notch (acute 8.6° ± 4.8°, chronic 7.8° ± 4.2° (p=0.013), failed ACLR 5.1° ± 5.9° (p=0.002)).

CONCLUSION

Our data suggests that attention should be paid peri-operatively to the required volume and location of notchplasty among the various ACL deficient states to minimize graft impingement.

Long-term sequelae and management following anterior cruciate ligament injury

This article discusses a case in which a patient who sustained an anterior cruciate ligament (ACL) injury returned with anterior knee pain in the same knee approximately 20 years later. He underwent reconstruction at the time of the injury and had a revision reconstruction performed 10 years later. The case highlights the long-term consequences of ACL injury and subsequent reconstruction for the knee joint, as this patient has developed anterior knee pain during his mid-40s. Additionally, non-operative management of knee osteoarthritis is discussed.

Incidence and trends of anterior cruciate ligament reconstruction in the United States

BACKGROUND

Anterior cruciate ligament (ACL) injury is among the most commonly studied injuries in orthopaedics. The previously reported incidence of ACL injury in the United States has varied considerably and is often based on expert opinion or single insurance databases.

PURPOSE

To determine the incidence of ACL reconstruction (ACLR) in the United States; to identify changes in this incidence between 1994 and 2006; to identify changes in the demographics of ACLR over the same time period with respect to location (inpatient vs outpatient), sex, and age; and to determine the most frequent concomitant procedures performed at the time of ACLR.

STUDY DESIGN

Descriptive epidemiological study.

METHODS

International Classification of Diseases, 9th Revision (ICD-9) codes 844.2 and 717.83 were used to search the National Hospital Discharge Survey (NHDS) and the National Survey of Ambulatory Surgery (NSAS) for the diagnosis of ACL tear, and the procedure code 81.45 was used to search for ACLR. The incidence of ACLR in 1994 and 2006 was determined by use of US Census Data, and the results were then stratified based on patient age, sex, facility, concomitant diagnoses, and concomitant procedures.

RESULTS

The incidence of ACLR in the United States rose from 86,687 (95% CI, 51,844-121,530; 32.9 per 100,000 person-years) in 1994 to 129,836 (95% CI, 94,993-164,679; 43.5 per 100,000 person-years) in 2006 (P = .015). The number of ACLRs increased in patients younger than 20 years and those who were 40 years or older over this 12-year period. The incidence of ACLR in females significantly increased from 10.36 to 18.06 per 100,000 person-years between 1994 and 2006 (P = .0003), while that in males rose at a slower rate, with an incidence of 22.58 per 100,000 person-years in 1994 and 25.42 per 100,000 person-years in 2006. In 2006, 95% of ACLRs were performed in an outpatient setting, while in 1994 only 43% of ACLRs were performed in an outpatient setting. The most common concomitant procedures were partial meniscectomy and chondroplasty.

CONCLUSION

The incidence of ACLR increased between 1994 and 2006, particularly in females as well as those younger than 20 years and those 40 years or older. Research efforts as well as cost-saving measures may be best served by targeting prevention and outcomes measures in these groups. Surgeons should be aware that concomitant injury is common.

Infection after arthroscopic anterior cruciate ligament reconstruction

Septic arthritis is a rare but potentially devastating complication of anterior cruciate ligament (ACL) reconstruction surgery. The purpose of this study was to provide an evidence-based summarization of the treatment and outcome of infection after ACL reconstruction with a pooled analysis of the reported cases. The authors conducted a systematic review of published studies that evaluated the outcome of septic arthritis after arthroscopic ACL reconstruction. A structured literature review of multiple databases referenced articles from 1950 to 2012. A total of 22,836 knees from 14 published studies were assessed. Postoperative septic arthritis occurred in 121 knees, with a pooled percentage of 0.5%. Mean duration of follow-up after ACL reconstruction was 53.6 months (range, 4-218 months). An average of 1.92 procedures (range, 1-5 procedures) were performed to eradicate the infection. The grafts were retained in 77% of cases. Postoperative intravenous antibiotics were used for at least 5 days (range, 5-90 days) after debridement. At final follow-up, mean postoperative Lysholm score was 80.2 (range, 23-100). No reinfection was observed in 121 patients. This study has helped to further elucidate the outcomes of infection after ACL reconstruction. Once an infection is encountered, culture-specific antibiotics and surgical joint irrigation with graft retention are recommended as initial treatment. Graft removal can be considered only for those infections resistant to initial treatment.

Avoiding Complications and Technical Variability During Arthroscopically Assisted Transtibial ACL Reconstructions by Using a C-Arm With Image Intensifier

BACKGROUND

Surgical reconstruction of the anterior cruciate ligament (ACL) can be complicated by incorrect and variable tunnel placement, graft tunnel mismatch, cortical breaches, and inadequate fixation due to screw divergence. This is the first report describing the use of a C-arm with image intensifier employed for the sole purpose of eliminating those complications during transtibial ACL reconstruction.

PURPOSE

To determine if the use of a C-arm with image intensifier during arthroscopically assisted transtibial ACL reconstruction (IIAA-TACLR) eliminated common complications associated with bone-patellar tendon-bone ACL reconstruction, including screw divergence, cortical breaches, graft-tunnel mismatch, and improper positioning of the femoral and tibial tunnels.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 110 consecutive patients (112 reconstructed knees) underwent identical IIAA-TACLR using a bone-patellar tendon-bone autograft performed by a single surgeon. Intra- and postoperative radiographic images and operative reports were evaluated for each patient looking for evidence of cortical breeching and screw divergence. Precision of femoral tunnel placement was evaluated using a sector map modified from Bernard et al. Graft recession distance and tibial α angles were recorded.

RESULTS

There were no femoral or tibial cortical breaches noted intraoperatively or on postoperative images. There were no instances of loss of fixation screw major thread engagement. There were no instances of graft-tunnel mismatch. The positions of the femoral tunnels were accurate and precise, falling into the desired sector of our location map (sector 1). Tibial α angles and graft recession distances varied widely.

CONCLUSION

The use of the C-arm with image intensifier enabled accurate and precise tunnel placement and completely eliminated cortical breach, graft-tunnel mismatch, and screw divergence during IIAA-TACLR by allowing incremental adjustment of the tibial tunnel and knee flexion angle. Incremental adjustment was essential to accomplish this. Importantly, a C-arm with image intensifier can be used with any ACL reconstruction that incorporates tunnels in the technique, with the expectation of increase in accuracy and precision and the elimination of common complications.

CLINICAL RELEVANCE

The use of an image intensifier during transtibial ACL reconstruction will substantially reduce the common complications associated with the procedure and improve both accuracy and precision of tibial and femoral tunnel placement. Use of an image intensifier unit is generalizable to an individual surgeon's preferences for graft choices and drilling techniques and will be especially valuable when the intercondylar architecture is altered from injury, time, or prior surgery.

Infections in anterior cruciate ligament reconstruction

Context:

Anterior cruciate ligament (ACL) reconstruction is a safe, common, and effective method of restoring stability to the knee after injury, but evolving techniques of reconstruction carry inherent risk. Infection after ACL reconstruction, while rare, carries a high morbidity, potentially resulting in a poor clinical outcome.

Evidence Acquisition:

Data were obtained from previously published peer-reviewed literature through a search of the entire PubMed database (up to December 2012) as well as from textbook chapters.

Results:

Treatment with culture-specific antibiotics and debridement with graft retention is recommended as initial treatment, but with persistent infection, consideration should be given to graft removal. Graft type likely has no effect on infection rates.

Conclusion:

The early diagnosis of infection and appropriate treatment are necessary to avoid the complications of articular cartilage damage and arthrofibrosis.

Two-stage procedure in anterior cruciate ligament revision surgery: a five-year follow-up prospective study

PURPOSE

The purpose of this study was to show that this two-stage procedure for ACL (anterior cruciate ligament) revision surgery could be straight-forward and provide satisfactory clinical and functional outcomes.

MATERIALS

This is a five-year prospective analysis of clinical and functional data on 30 patients (19 men and 11 women; average age 29.1 ± 5.4) who underwent a two-stage ACL revision procedure after traumatic re-rupture of the ACL. Diagnosis was on Lachman and pivot-shift tests, arthrometer 30-lb KT-1000 side-to-side findings, and on MRI and arthroscopic assessments.

RESULTS

Postoperative IKDC and Lysholm scores were significantly improved compared to baseline values (P < 0.001). At the last follow up, 20 of 30 patients (66.7%) had returned to preoperative sport activity level (nine elite athletes, 11 county level), seven had changed to lower sport levels, and three had given up any sport activity. At the same appointment, 11 patients had degenerative changes. All these patients reported significantly lower Lysholm scores compared to patients without any degenerative change (p < 0.001).

CONCLUSIONS

In ACL revision surgery, when the first femoral tunnel has been correctly placed, this procedure allows safe filling of large bony defects, with no donor site comorbidities. It provides comfortable clinical, functional and imaging outcomes.

Programmable mechanical stimulation influences tendon homeostasis in a bioreactor system

Identification of functional programmable mechanical stimulation (PMS) on tendon not only provides the insight of the tendon homeostasis under physical/pathological condition, but also guides a better engineering strategy for tendon regeneration. The aims of the study are to design a bioreactor system with PMS to mimic the in vivo loading conditions, and to define the impact of different cyclic tensile strain on tendon. Rabbit Achilles tendons were loaded in the bioreactor with/without cyclic tensile loading (0.25 Hz for 8 h/day, 0-9% for 6 days). Tendons without loading lost its structure integrity as evidenced by disorientated collagen fiber, increased type III collagen expression, and increased cell apoptosis. Tendons with 3% of cyclic tensile loading had moderate matrix deterioration and elevated expression levels of MMP-1, 3, and 12, whilst exceeded loading regime of 9% caused massive rupture of collagen bundle. However, 6% of cyclic tensile strain was able to maintain the structural integrity and cellular function. Our data indicated that an optimal PMS is required to maintain the tendon homeostasis and there is only a narrow range of tensile strain that can induce the anabolic action. The clinical impact of this study is that optimized eccentric training program is needed to achieve maximum beneficial effects on chronic tendinopathy management.

Allograft salvage procedure in multiple-revision anterior cruciate ligament reconstruction

BACKGROUND

Multiple-revision anterior cruciate ligament (ACL) reconstructions represent a surgical challenge due to the presence of previous tunnels, hardware, injuries to the secondary stabilizers, and difficulties in retrieving autologous tendons. An anatomic ACL reconstruction may therefore result in a demanding surgery, thus requiring 2 stages.

PURPOSE

To analyze the efficacy of an over-the-top ACL reconstruction technique plus extra-articular plasty using Achilles or tibialis posterior tendon allograft in restoring knee stability in patients with at least 2 failed previous ACL reconstructions, as well as to evaluate the factors able to affect the final outcome.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From 2002 to 2008, 24 male athletes with a mean age of 30.8 years underwent surgery. Twenty patients had undergone 2, whereas 4 patients had undergone 3 previous reconstructions. The International Knee Documentation Committee (IKDC) score and KT-2000 arthrometric evaluation were used to measure outcomes at a mean follow-up period of 3.3 years (range, 2-7).

RESULTS

The mean ± SD IKDC subjective score at follow-up was 81.3 ± 14.0. The IKDC objective score was an A or B in 20 patients (83%). Arthrometer side-to-side difference averaged 3.1 ± 1.1 mm. Range of motion was normal or nearly normal in 23 patients and abnormal in 1. Of the 20 good results, 17 patients resumed sports activity at the preinjury level.

CONCLUSION

A 2-stage revision is an accepted option in cases of excessive tunnel enlargement and bone loss, especially on the femoral side, to achieve anatomic reconstruction. Nonanatomic over-the-top ACL reconstruction and lateral extra-articular plasty technique allow one to overcome difficult anatomic situations on the femoral side, permitting a 1-step surgery. The overall results obtained in this series are comparable with those of other ACL revision series. The higher rate of mild instability observed in our series may not be attributable to the surgical technique but rather to the chronic instability suffered by these knees before last revision.

Gender differences in landing mechanics vary depending on the type of landing

OBJECTIVE

Men and women exhibit different movement patterns, which are thought to contribute to the increased incidence of anterior cruciate ligament injuries in females. Although gender differences have been observed in movement, few studies have examined gender differences during different types of landings.

DESIGN

Prospective gender comparison study.

SETTING

Controlled laboratory study.

PATIENTS

Fourteen male and 14 female recreational soccer players were recruited for the study. All subjects performed a soccer-specific jump heading activity to examine differences in landing mechanics before and after heading the soccer ball. Subjects began the task by performing a forward jump onto 2 force platforms (landing 1) and conducting a countermovement before jumping up to head a soccer ball that was hanging above the force platform before, then landing back on the force platforms (landing 2).

MAIN OUTCOME MEASURES

A 2-way analysis of variance (gender × landing) was performed to examine the interaction between gender and different types of landings on sagittal plane joint mechanics.

RESULTS

Significant interactions existed for the peak hip extension moment and vertical ground reaction force where the male players exhibited increased values during the second landing compared with the female players. Males exhibited greater peak plantarflexion and knee extension moments, but decreased peak hip flexion. Main effects for landing exhibited lower kinematic and larger kinetic values except for the peak plantarflexion moment.

CONCLUSIONS

Female and male players appear to land differently depending on the type of landing. Therefore, specificity of landing type may be important to consider when screening for injury risk factors.

CLINICAL RELEVANCE

This study examines the differences between genders during 2 different landing tasks and demonstrates the importance of considering the jumping task when screening individuals for injury risk factors.

Evaluation of outcomes in conservatively managed concomitant Type A and B posterolateral corner injuries in ACL deficient patients undergoing ACL reconstruction

INTRODUCTION

There is paucity of literature regarding the outcomes of ACL reconstruction in ACL deficient knees with concomitant Type A and Type B PLC injuries.

MATERIALS AND METHODS

A total of 102 patients undergoing isolated ACL reconstruction for an ACL injury were evaluated prospectively in this study. The patients with divided into three groups: group A with isolated ACL injury, group B1 with concomitant Type A PLC injury and group B2 with concomitant Type B PLC injury. The associated PLC injury in all these patients was managed conservatively. Outcome assessment was based on IKDC scores measured preoperatively and at last follow up visits.

RESULTS

The mean age of the patients was 25.33 years (16-38 years) with 95 males and seven females. The average follow up was almost 2.5 years (13-46 months). Group A had 88 patients while groups B1 and B2 had six and eight patients respectively. The preoperative IKDC scores were comparable for all the groups. The follow up IKDC scores were similar (statistically insignificant, p value: 0.421) for group A and group B1. Group B2 had poorer follow up IKDC scores as compared to group A and this result was found to be statistically significant (p value: 0.0001).

CONCLUSION

Conservative management of a concomitant Type B PLC injury adversely affects the outcomes of ACL reconstruction in these patients. Type A PLC injuries, on the other, do well without surgery and can be left as such even when associated with a concomitant ACL tear.

LEVEL OF EVIDENCE

Level 2.

Failure of anterior cruciate ligament reconstruction

Failure after anterior cruciate ligament reconstruction is a potentially devastating event that affects a predominantly young and active population. This review article provides a comprehensive analysis of the potential causes of failure, including graft failure, loss of motion, extensor mechanism dysfunction, osteoarthritis, and infection. The etiology of graft failure is discussed in detail with a particular emphasis on failure after anatomic anterior cruciate ligament reconstruction.

Evaluation of a one-stage ACL revision technique using bone void filler after cyclic loading

BACKGROUND

Revision anterior cruciate ligament (ACL) reconstruction often requires a two-stage approach. This study analyzes the biomechanical properties after cyclic loading of a one-stage ACL revision technique using a calcium phosphate bone cement.

METHODS

Arthroscopic reconstruction of the ACL was performed in 5 matched pairs of fresh-frozen cadaveric knees separated into two groups. The control group underwent a standard reconstruction with a bone-patellar tendon-bone autograft with bioabsorbable interference screw fixation. The experimental group simulated a failed reconstruction by drilling a 12 mm hole and underwent a revision after filling it with a bioabsorbable calcium phosphate bone cement. The specimens were dissected, scanned for bone mineral density, and cyclically loaded on a mechanical testing system (preload of 250 cycles of 5-75 N at 0.5 Hz followed by 10,000 cycles of 20-150 N at 1 Hz). Intact specifmens underwent a load-to-failure protocol of 50mm/min. Ultimate load, stiffness, and modes of failure were recorded. Data was analyzed using paired t-tests.

FINDINGS

All specimens completed the mechanical testing protocol. The control group had a mean maximum load of 471.33 N (SD 220.73 N) and the experimental group had 453.54 N (SD 152.36; p=0.84). There were no statistically significant differences in maximum load or stiffness. No correlation between bone mineral density (BMD) and maximum load was found.

INTERPRETATION

Using calcium phosphate filler in a single-stage ACL revision is biomechanically viable. Further testing of long-term incorporation of the ACL graft in an animal model, along with human clinical trials, should be performed before there is clinical acceptance of this technique.

The lateral tibial tunnel in revision anterior cruciate ligament surgery: a biomechanical study of a new technique

PURPOSE

To evaluate the cortical entry point and the length of a revision lateral tibial tunnel (LTT) in a human cadaveric study and to investigate knee stability after a revision anterior cruciate ligament (ACL) reconstruction with an LTT.

METHODS

Ten human cadaveric knee specimens were used to perform a preliminary investigation. Twenty-two human proximal tibias were used to compare the length of a revision LTT with a classical medial tibial tunnel (MTT). Another 5 human cadaveric knees were used to investigate knee stability after a revision LTT and to compare it with a primary ACL repair with an MTT performed in the same knees. Stability was evaluated with computer navigation.

RESULTS

An LTT is statistically significantly longer (45.0 mm) than an MTT (35.2 mm) (P < .001). There was no evidence of a length difference between the intact bone tube length of a revision LTT (36.5 mm) and an MTT. For nearly all measurements, the difference between the ACL repair with an MTT and the revision surgery with an LTT was not only nonsignificant but also small in magnitude. Only for internal rotation at 30° of knee flexion and for internal rotation in extension was a significant difference detected (P = .029 and P = .044, respectively).

CONCLUSIONS

An LTT can easily be drilled and provides a bony tunnel that is statistically significantly longer than an MTT. A revision LTT has an intact bone tube as long as that of a primary MTT. Similar stability is obtained after revision ACL surgery with an LTT compared with a primary ACL repair with a standard MTT.

CLINICAL RELEVANCE

LTT placement is a new technique for ACL revision surgery that can help to overcome problems related to tunnel enlargement in the distal part of the tibial tunnel.

BIOMECHANICAL STUDY OF TRANSCORTICAL OR TRANSTRABECULAR BONE FIXATION OF PATELLAR TENDON GRAFT WITH BIOABSORBABLE PINS IN ACL RECONSTRUCTION IN SHEEP

Objective: To determine the initial resistance of fixation using the Rigid Fix^® system, and compare it with traditional fixation methods using metal interference screws; and to evaluate the resistance of the fixation with the rigid fix system when the rotational position of the bone block is altered in the interior of the femoral tunnel. Methods: forty ovine knee specimens (stifle joints) were submitted to anterior cruciate ligament reconstruction (ACL) using a bone-tendon-bone graft. In twenty specimens, the Rigid Fix method was used; this group was subdivided into two groups: ten knees the pins transfixed only the spongious area of the bone block, and ten for fixation passing through the layer of cortical bone. In the twenty remaining specimens, the graft was fixed with 9mm metal interference screws. Results: comparison of the RIGIDFIX^® method with the metal interference screw fixation method did not show any statistically significant differences in terms of maximum load and rigidity; also, there were no statistically significant differences when the rotational position of the bone block was altered inside the femoral tunnel. For these evaluations, a level of significance of p < 0.017 was considered. Conclusion: fixation of the bone-tendon-bone graft with 2 bioabsorbable pines, regardless of the rotational position inside the femoral tunnel, gave a comparable fixation in terms of initial resistance to the metal interference screw, in this experimental model.

Tissue-engineering strategies for the tendon/ligament-to-bone insertion

Injuries to connective tissues are painful and disabling and result in costly medical expenses. These injuries often require reattachment of an unmineralized connective tissue to bone. The uninjured tendon/ligament-to-bone insertion (enthesis) is a functionally graded material that exhibits a gradual transition from soft tissue (i.e., tendon or ligament) to hard tissue (i.e., mineralized bone) through a fibrocartilaginous transition region. This transition is believed to facilitate force transmission between the two dissimilar tissues by ameliorating potentially damaging interfacial stress concentrations. The transition region is impaired or lost upon tendon/ligament injury and is not regenerated following surgical repair or natural healing, exposing the tissue to risk of reinjury. The need to regenerate a robust tendon-to-bone insertion has led a number of tissue engineering repair strategies. This review treats the tendon-to-bone insertion site as a tissue structure whose primary role is mechanical and discusses current and emerging strategies for engineering the tendon/ligament-to-bone insertion in this context. The focus lies on strategies for producing mechanical structures that can guide and subsequently sustain a graded tissue structure and the associated cell populations.

Anterior cruciate ligament reconstruction creating the femoral tunnel through the anteromedial portal. Surgical technique

The anterior cruciate ligament reconstruction is a common procedure that improves stability and function of the knee. The surgical technique continues to evolve and many issues are still under debate. These mainly include: (1) graft selection (patellar tendon, hamstring, quadriceps tendon, or allografts), (2) surgical technique (double versus single bundle), and (3) femoral tunnel drilling. Currently, the most controversial one is the femoral tunnel drilling (transtibial vs. anteromedial portal drilling). Common opinion is that drilling the femoral tunnel through the anteromedial (AM) allows a more anatomic placement of the graft and a better rotational stability; therefore, this technique is gaining in popularity compared with the transtibial drilling despite a greater difficulty and the risk of medial condyle damage, tunnel back wall blowout, and inadequate socket length. The aim of this article is to describe the surgical technique of the anterior cruciate ligament reconstruction (single and double bundle), drilling the femoral tunnel through the AM portal.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING THE DOUBLE-BUNDLE TECHNIQUE – EVALUATION IN THE BIOMECHANICS LABORATORY

Objective: The objective of this study was to describe the methodology of knee rotation analysis using biomechanics laboratory instruments and to present the preliminary results from a comparative study on patients who underwent anterior cruciate ligament (ACL) reconstruction using the double-bundle technique. Methods: The protocol currently used in our laboratory was described. Three-dimensional kinematic analysis was performed and knee rotation amplitude was measured on eight normal patients (control group) and 12 patients who were operated using the double-bundle technique, by means of three tasks in the biomechanics laboratory. Results: No significant differences between operated and non-operated sides were shown in relation to the mean amplitudes of gait, gait with change in direction or gait with change in direction when going down stairs (p > 0.13). Conclusion: The preliminary results did not show any difference in the double-bundle ACL reconstruction technique in relation to the contralateral side and the control group.

The ability of 3 different approaches to restore the anatomic anteromedial bundle femoral insertion site during anatomic anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to determine whether drilling the femoral tunnel when performing anterior cruciate ligament (ACL) reconstruction through the accessory medial portal, as opposed to drilling the tunnel transtibially, will lead to more frequent location of the anteromedial femoral tunnel within the anatomic anteromedial bundle insertion site.

METHODS

Primary anatomic double-bundle reconstruction was performed on 113 patients. Intraoperatively, we placed a guide pin through the anteromedial and posterolateral tibial tunnels and accessory medial portal, attempting to reach the center of the native femoral anteromedial bundle insertion. For each approach, the position of the guide pin was classified as (1) within the center of, (2) off-center within, or (3) outside of the femoral anteromedial insertion.

RESULTS

There were significant differences in the ability of each approach to reach the center of the femoral anteromedial bundle insertion. Through the tibial anteromedial tunnel, the femoral anteromedial insertion center was reached in 4.4% of cases, whereas it was off-center within and outside of the femoral anteromedial insertion in 23.0% and 72.6%, respectively. Through the tibial posterolateral tunnel, the femoral anteromedial insertion center was reached in 60.2% of cases, whereas it was off-center within and outside of the femoral anteromedial insertion in 23.9% and 15.9% of cases, respectively. When approached from the accessory medial portal, the center of the femoral anteromedial insertion was reached in 100% of the cases. Ultimately, the femoral anteromedial tunnel was drilled through the tibial anteromedial tunnel in 0.9%, through the posterolateral tunnel in 62.8%, and through the accessory medial portal in 36.3% of cases.

CONCLUSIONS

Drilling the femoral tunnel for the anteromedial graft through the accessory medial portal, as opposed to drilling the tunnel transtibially, leads to more frequent location of the anteromedial femoral tunnel within the anterior cruciate ligament anteromedial bundle anatomic footprint.

Computer-navigated surgery in anterior cruciate ligament reconstruction: are radiographic outcomes better than conventional surgery?

PURPOSE

The use of computer navigation systems in anterior cruciate ligament (ACL) has been the subject of debate. However, there is a lack of systematic review to analyze the radiographic outcomes after computer-navigated ACL reconstruction.

METHODS

We searched, in duplicate, Medline, Embase, and Web of Science databases for randomized controlled trials (RCTs)/quasi-RCTs comparing conventional versus computer-navigated ACL reconstruction. Two reviewers independently extracted the data. Radiographic outcomes reported in a majority of included trials were meta-analyzed using the Mantel-Haenszel test statistic.

RESULTS

After applying our eligibility criteria, we had 5 trials for systematic review and data synthesis. There was no evidence of statistical heterogeneity between all included studies. Both navigated and conventional ACL reconstructions placed the tibial tunnel in acceptable positions. The risk of notch impingement was reduced in the navigated group in comparison with the conventional group.

CONCLUSIONS

A computer navigation systems may reduce variation from optimal graft alignment and notch impingement. However, there is a need for further high-quality studies with long-term follow-up, so as to prove the clinical significance of these findings.

LEVEL OF EVIDENCE

Level II, systematic review of randomized controlled trials.

Radiographic results of femoral tunnel drilling through the anteromedial portal in anterior cruciate ligament reconstruction

PURPOSE

The goal of this study was to determine the femoral tunnel position by use of the head of a metallic femoral interference screw as a reference marker. In addition, we present postoperative films from an anatomically placed single-bundle anterior cruciate ligament with femoral interference screw fixation using the anteromedial portal drilling technique.

METHODS

Two surgeons evaluated 43 random postoperative radiographs in patients who underwent anterior cruciate ligament reconstruction by a single surgeon. Four measurements were taken on lateral knee radiographs with superimposed condyles for each patient. These included the total sagittal diameter of the lateral condyle measured along the Blumensaat line (A1), the maximum intercondylar height from the Blumensaat line to the condyle edge along the center of the screw head (B1), the distance from the center of the screw head to the most dorsal contour of the lateral condyle (A2), and the distance from the center of the screw head to the Blumensaat line (B2). The latter 2 values were then expressed as percentages of the lengths A1 and B1. From the anteroposterior (AP) films, the angle between the axis of the screw and anatomic axis of the femur was determined.

RESULTS

The center of the screw head was 31.3% of the Blumensaat line and 24.8% of the condylar height. The axis of the screw was found to be 43° from the anatomic axis of the femur on the AP radiographs.

CONCLUSIONS

The mean center of the screw head was 31.3% of the Blumensaat line and 24.8% of the condylar height. The mean axis of the screw was found to be 43° from the anatomic axis of the femur on the AP radiographs. Furthermore, we have described the appearance of a lateral radiograph with this technique.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Allograft compared with autograft infection rates in primary anterior cruciate ligament reconstruction

BACKGROUND

Injuries to the anterior cruciate ligament are the most common surgically treated knee ligament injury. There is no consensus regarding the optimal graft choice between allograft and autograft tissue. Postoperative septic arthritis is an uncommon complication after anterior cruciate ligament reconstruction. The purpose of this study was to compare infection rates between procedures with use of allograft and autograft tissue in primary anterior cruciate ligament reconstruction.

METHODS

A combined prospective and retrospective multicenter cohort study was performed over a three-year period. Graft selection was determined by the individual surgeon. Inclusion and exclusion criteria were equivalent for the two groups (allograft and autograft tissue). Data collected included demographic characteristics, clinical information, and graft details. Patients were followed for a minimum of 5.5 months postoperatively. Our primary outcome was intra-articular infection following anterior cruciate ligament reconstruction.

RESULTS

Of the 1298 patients who had anterior cruciate ligament reconstruction during the study period, 861 met the criteria for inclusion and formed the final study group. Two hundred and twenty-one patients (25.6%) received an autograft, and 640 (74.3%) received an allograft. There were no cases of septic arthritis in either group. The 95% confidence interval was 0% to 0.57% for the allograft group and 0% to 1.66% for the autograft group. The rate of superficial infections in the entire study group was 2.32%. We did not identify a significant difference in the rate of superficial infections between autograft and allograft reconstruction in our study group.

CONCLUSIONS

While the theoretical risk of disease transmission inherent with allograft tissue cannot be eliminated, we found no increased clinical risk of infection with the use of allograft tissue compared with autologous tissue for primary anterior cruciate ligament reconstruction.

Comparison of plain radiography, computed tomography, and magnetic resonance imaging in the evaluation of bone tunnel widening after anterior cruciate ligament reconstruction

Bone tunnel widening poses a problem for graft fixation during revision anterior cruciate ligament (ACL) reconstruction. Large variability exists in the utilization of imaging modalities for evaluating bone tunnels in pre-operative planning for revision ACL reconstruction. The purpose of this study was to identify the most reliable imaging modality for identifying bone tunnels and assessing tunnel widening, and specifically, to validate the reliability of radiographs, MRI, and CT using intra- and inter-observer testing. Data was retrospectively collected from twelve patients presenting for revision ACL surgery. Five observers twice measured femoral and tibial tunnels at their widest point using digital calipers in coronal and sagittal planes. Measurements were corrected for magnification. Tunnel identification, diameter measurements, and cross-sectional area (CSA) calculations were recorded. A categorical classification of tunnel measurements was created to apply clinical significance to the measurements. Using kappa statistics, intra- and inter-observer reliability testing was performed. CT demonstrated excellent intra- and inter-observer reliability for tunnel identification. Intra- and inter-observer reliability was significantly less for MRI and radiographs. CT revealed superior reliability versus either radiographs or MRI for CSA analysis. Intra-observer kappa scores for tibial CSA using CT, radiographs, and MRI were 0.66, 0.5, and 0.37, respectively. Inter-observer kappa scores for tibial CSA using CT, radiographs, and MRI were 0.65, 0.39, and 0.32, respectively. Our results demonstrate CT is the most reliable imaging modality for evaluation of ACL bone tunnels as proven by superior intra- and inter-observer testing results when compared to MRI and radiographs. Radiographs and MRI were not reliable, even for simply identifying the presence of a bone tunnel.

The femoral insertions of the anteromedial and posterolateral bundles of the anterior cruciate ligament: a radiographic evaluation

The aim of this radiographic study was to visualize the femoral insertion sites of the anteromedial (AM) and posterolateral (PL) bundle of the anterior cruciate ligament (ACL) on lateral radiographs in different angles of knee flexion to gain better understanding for arthroscopic femoral tunnel placement in ACL double bundle reconstruction. Four fresh cadaveric knees with an intact ACL were dissected to isolate the AM and PL bundle of the ACL. We obtained lateral radiographs of each knee over the range of 0 degrees -90 degrees flexion in 30 degrees increments after painting the bundles with a radiopaque tantalum powder. The center of the radiographically marked femoral insertion was defined for each bundle on the lateral roentgenogram. We analyzed the relationship of knee flexion and the projection of the relative position of the femoral insertion sites of both bundles of the ACL on the lateral roentgenogram. The centre of the PL bundle visualized more anterior and distal than the centre of the AM bundle with the knee held in 90 degrees flexion. The centers of the AM and PL bundle were horizontally aligned when the knee was flexed over 90 degrees . The resulting images allow a radiographic description of the femoral insertion sites of both bundles in different angles of knee flexion. It is essential to be aware of the degree of knee flexion when drilling the femoral tunnels.

Biomechanical evaluation of a 1-stage revision anterior cruciate ligament reconstruction technique using a structural bone void filler for femoral fixation

PURPOSE

The purpose of this study was to develop a method of femoral fixation for complex revision anterior cruciate ligament (ACL) reconstructions that would avoid a staged bone grafting approach. We evaluated the use of a calcium phosphate cement as a structural bone void filler that would allow for a single-stage revision ACL reconstruction with initial biomechanical properties equivalent to standard autologous bone-patellar tendon-bone primary ACL reconstruction.

METHODS

We tested 11 matched pairs of fresh-frozen cadaveric knees (N = 22). Controls were treated with autologous bone-patellar tendon-bone primary ACL reconstruction fixed with bioabsorbable interference screws with a 1-mm back wall. The contralateral knee of each pair had a large bone void created that would hamper subsequent femoral fixation to simulate revision ACL reconstruction conditions. This defect was filled with calcium phosphate cement arthroscopically. After solidification, the femoral tunnel was drilled through the bone void filler and native bone with a 1-mm back wall, allowing anatomic positioning. The autologous graft was then placed and fixed with a bioabsorbable interference screw. Specimens were then tested in an MTS machine (MTS Systems, Eden Prairie, MN) for load to failure according to a standard protocol and compared with matched controls.

RESULTS

Failure loads for the control group averaged 312 N (standard deviation [SD], 127 N) and were not significantly different compared with the calcium phosphate cement revision group, which averaged 301 N (SD, 95 N) (P = .80). Failure occurred at the femoral bone block in both groups but without screw pullout.

CONCLUSIONS

Statistical analysis failed to show a significant difference between the control group and the group undergoing structural bone void filler revision in this biomechanical evaluation of initial fixation strength.

CLINICAL RELEVANCE

This technique may allow surgeons to perform a single-stage revision ACL reconstruction in the presence of a contained bone void and avoid the need for a staged procedure if clinical studies verify long-term incorporation of the bone void filler.

Tibial fixation of anterior cruciate ligament allograft tendons: comparison of 1-, 2-, and 4-stranded constructs

BACKGROUND

In sum, 1-, 2-, and 4-stranded allografts are used for soft tissue anterior cruciate ligament reconstruction; however, the fixation properties of fixation devices are not well assessed.

HYPOTHESIS

There are no differences in the biomechanical characteristics of 1 (Achilles)-, 2 (posterior tibialis)-, and 4 (semitendinosus)-stranded allograft tibial fixation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sixty-three fresh-frozen porcine tibiae were used to evaluate the fixation of 1-, 2-, and 4-stranded human tendon allografts (Achilles, posterior tibialis, and semitendinosus) with 3 fixation devices (Delta, Intrafix, and Calaxo screws). With use of a materials testing system, each graft was subjected to 500 cycles of loading (50-250 N, 0.75 mm/sec) to determine displacement and cyclic stiffness, followed by a monotonic failure test (20 mm/min) to determine maximum load and pullout stiffness.

RESULTS

For each graft type, there were no significant biomechanical differences between fixation devices. However, the 1-stranded graft (Achilles) construct demonstrated significantly higher mean displacement (3.17 +/- 1.62 mm), lower cyclical stiffness (156 +/- 25 N/mm), lower load to failure (479 +/- 87 N), and lower pullout stiffness (140 +/- 28 N/mm). In comparison with the 2-stranded graft (posterior tibialis), the 4-stranded graft (semitendinosus) exhibited lower displacement (0.86 +/- 0.44 to 1.12 +/- 0.51 mm) and higher ultimate failure load (832 +/- 255 to 656 +/- 168 N). Numerous differences in fixation properties were noted when comparing a device to each of the 3 grafts.

CONCLUSION

The 1-stranded allograft demonstrated inferior biomechanical tibial fixation properties when compared with 2 (posterior tibialis)- and 4 (semitendinosus)-stranded allograft constructs for all fixation devices tested.

CLINICAL RELEVANCE

This study demonstrated that not all tibial fixation devices are designed to adequately accommodate different types of anterior cruciate ligament allografts. Biomechanical evidence suggests that caution is warranted when using an Achilles allograft fixated solely with an interference device.

Anterior cruciate ligament graft reconstruction: clinical, technical, and imaging overview

The anterior cruciate ligament (ACL) is one of the most frequently torn ligaments of the knee. With more than 100,000 ACL reconstructions performed yearly in the United States, evaluation of ACL grafts with magnetic resonance imaging is a common occurrence in daily clinical practice. Anterior cruciate ligament reconstructions vary from single bundle, double bundle, selective bundle, and physeal-sparing techniques. Complications of ACL graft reconstructions include graft tears, graft laxity, arthrofibrosis, and hardware failure or migration. This article offers a comprehensive review of ACL reconstruction for the consulting radiologist.

Inhibition of anterior tibial translation or axial tibial rotation prevents anterior cruciate ligament failure during impact compression

BACKGROUND

Anterior cruciate ligament injury is prevalent in activities involving large and rapid landing impact loads.

HYPOTHESIS

Inhibition of anterior tibial translation/axial tibial rotation forestalls the ligament from failing at the range of peak compressive load that can induce ligament failure when both factors are unrestrained.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sixteen porcine knee specimens were mounted onto a material testing system at 70 degrees of flexion and were divided into 4 test groups: impact compression without restraint (IC), anterior tibial translation restraint (ICA), axial tibial rotation restraint (ICR), and combination of both restraints (ICC). Compression was successively repeated with increasing actuator displacement until ligament failure or visible bone fracture was observed. During compression, rotational and translational joint data were obtained using a motion capture system.

RESULTS

The IC group underwent ligament failure via femoral avulsion; the peak compressive force during failure ranged from 1.4 to 4.0 kN. The ICA, ICR, and ICC test groups developed visible bone fracture with the ligament intact; the peak compressive force during fracture ranged from 2.2 to 6.9 kN. Posterior femoral displacement and axial tibial rotation for the ICA and ICR groups, respectively, were significantly lower relative to the IC group (P < .05). Both factors were substantially reduced in the ICC group, but peak compressive force was higher compared with the IC group (P < .05).

CONCLUSION

Substantial inhibition of these factors in an impact setup, which can induce ligament failure with the factors unrestrained, was able to prevent failure.

CLINICAL RELEVANCE

Adequate inhibition of anterior tibial translation and axial tibial rotation by knee bracing during injurious impact is necessary for effective ligament protection.

A retrospective comparison of the incidence of bacterial infection following anterior cruciate ligament reconstruction with autograft versus allograft

PURPOSE

To compare the incidence of bacterial infection in anterior cruciate ligament (ACL) reconstruction with autograft versus allograft.

METHODS

We completed a retrospective medical record review of ACL reconstructions performed at our institutions between 2001 and 2005. These included 170 autograft, 628 allograft, and 3 combined autograft/allograft reconstructions. Data collection included patient demographics, comorbidities, preoperative antibiotics, fixation type, and the occurrence of deep postoperative infection.

RESULTS

Of the 801 patients who underwent ACL reconstruction, 6 (0.75%) developed a confirmed deep infection. There were 2 confirmed deep infections in 170 autograft reconstructions (1.2%) compared with 4 confirmed deep infections in 628 allograft reconstructions (0.6%). Multivariate analysis revealed that ACL reconstruction using autograft had a nearly twice the risk of infection compared to allograft reconstructions (adjusted odds ratio, 1.83; 95% confidence interval, 0.16 to 12.94).

CONCLUSIONS

This study failed to find a higher rate of deep bacterial infection in ACL reconstructions when allograft tissue was used. We therefore feel that surgeons should consider allograft tissue as an alternative to autograft when there is a concern about donor-site morbidity, or for revision reconstructions.

LEVEL OF EVIDENCE

Level III, therapeutic retrospective comparative study.

A simple technique for introducing bone graft during revision ACL surgery

Bone grafting of the tibial tunnel is often required when performing revision ACL surgery. We describe a simple method of introducing bone graft which allows accurate delivery and is quick and easy to perform.

Anterior cruciate ligament revision reconstruction: results in 107 patients

BACKGROUND

Although techniques and options for suitable graft substitutes for anterior cruciate ligament surgery continue to improve, failures occur because of many reasons. Errors in surgical techniques seem to be important reasons.

HYPOTHESIS

Inappropriate positioning of the tunnels may be the most important reason for these failures. Anatomical anterior cruciate ligament revision reconstruction, using autografts, may yield acceptable outcomes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This retrospective study involved 148 anterior cruciate ligament revision reconstructions performed in our hospital using autografts. One hundred and seven patients were followed up at a mean of 72.9 +/- 20.6 months. Clinical evaluation was performed using the Lysholm score, the Tegner rating system, the International Knee Documentation Committee evaluation form, and the KT-1000 arthrometer. Radiographs were evaluated for signs of osteoarthritis according to the Jaeger and Wirth classification.

RESULTS

Inappropriate positioning of the tunnels was the most important reason (63.5%) for anterior cruciate ligament reconstruction failure. The average Lysholm score improved significantly at the follow-up (88.5 +/- 12.4 vs 51.5 +/- 24.9; P < .001). Moreover, the average Tegner activity score improved significantly compared with the activity score before revision surgery (6.3 +/- 1.8 vs 2.8 +/- 1.8; P < .001). The International Knee Documentation Committee score was A in 17 cases, B in 45, C in 37, and D in 8. Radiographic evaluation revealed that 33 patients had degenerative findings of grade I, 35 of grade II, 16 of grade III, and 2 of grade IV.

CONCLUSION

Anatomical anterior cruciate ligament revision reconstruction provides satisfactory midterm results as far as stability and function of the knee are concerned. In spite of these favorable subjective and objective results, the radiological evaluation revealed a significant progression of osteoarthritis.

In vivo evaluation of a tri-phasic composite scaffold for anterior cruciate ligament-to-bone integration

The widespread clinical implementation of hamstring tendon (HT) autografts for anterior cruciate ligament (ACL) reconstruction is currently limited by the unpredictable integration of the graft with subchondral bone and a lack of devices that are capable of promoting biological fixation of HT grafts to bone. The site of HT graft fixation within the bone tunnel has been identified as the weak point in the reconstructed ACL, likely due to the failure of the graft to reestablish the physiological tendon-bone interface capable of transmitting load from the ligament to bone while minimizing stress concentration at the interface. Although a fibrovascular tissue has been shown to form at the graft-bone interface, this fibrovascular tissue is non-anatomically oriented compared to the native fibrocartilage found at direct ligament to bone insertions. Interface tissue engineering embodies a new approach for graft fixation, focusing on securing tendon grafts to bone via biological fixation wherein the complex functional interface found natively at tendon and ligament junctions with bone are regenerated at the graft insertion site into the bone tunnels. This study focuses on the in vivo evaluation of a novel biomimetic, triphasic scaffold system co-cultured with relevant cell types found at the graft-bone interface, specifically fibroblasts, chondrocytes, and osteoblasts. The scaffold is intended to promote biological fixation of HT grafts to bone by guiding the reestablishment of an anatomically-oriented and mechanically functional fibrocartilage interfacial region. It was found that the cell-seeded triphasic scaffolds supported cellular interactions as well as tissue infiltration and abundant matrix production in vivo. In addition, controlled phase-specific matrix heterogeneity was induced on the scaffold, with distinct mineral and interface-like tissue regions. The results of this study demonstrate the feasibility of multi-tissue regeneration on a single graft, as well as th- e potential of interface tissue engineering to enable the biological fixation of soft tissue grafts to bone.

Use of a bioscaffold to improve healing of a patellar tendon defect after graft harvest for ACL reconstruction: A study in rabbits

Following harvest of a bone-patellar tendon-bone (BPTB) autograft, the central third of the patellar tendon (PT) does not heal well. The healing tissues also form adhesions to the fat pad and can cause abnormal patellofemoral joint motion. The hypotheses were that a bioscaffold could enhance patellar tendon healing through contact guidance and chemotaxis, and the scaffold could serve as a barrier to decrease adhesion formation between the neo-PT and infrapatellar fat pad. In 20 New Zealand White rabbits, a central-third PT defect was created. One strip of porcine small intestinal submucosa (SIS) was attached to both the anterior and posterior sides of the PT defect of the SIS-treated group (n = 10). For comparison, a central defect was left nontreated (n = 10). At 12 weeks, histomorphology was examined using Masson's trichrome staining. The cross-sectional area (CSA) was determined with a laser micrometer, and the central BPTB complexes were tested in uniaxial tension. SIS-treated samples showed a greater amount of healing tissue with denser and well-oriented collagen fibers and more spindle-shaped cells. There was no noticeable adhesion formation in the SIS-treated group. For the nontreated group, there were significantly more and diffuse adhesive formations. The SIS-treated group also had a 68% increase in neo-PT CSA, 98% higher stiffness, and 113% higher ultimate load than that in the nontreated group. SIS treatment increased the quantity of healing tissue, improved the histological appearance and biomechanical properties of the neo-PT, and prevented adhesion formation between the PT and fat pad.

Tunnel positioning of anteromedial and posterolateral bundles in anatomic anterior cruciate ligament reconstruction: anatomic and radiographic findings

BACKGROUND

The interest in double-bundle anterior cruciate ligament (ACL) reconstructions has recently reawakened.

HYPOTHESIS

The center of the femoral posterolateral (PL) bundle and the center of the femoral anteromedial (AM) bundle are not within the same plane and change their orientation throughout passive knee flexion. Additionally, the tibial center of the AM bundle is aligned with the anterior horn of the lateral meniscus and the center of the PL bundle lies at the recommended tibial tunnel position for single-bundle ACL reconstruction reconstruction, 7 to 9 mm anterior to the posterior cruciate ligament.

STUDY DESIGN

Descriptive laboratory study.

MATERIALS

In 20 human cadaveric knees (age range, 45-87 years) the distances from the center of the AM and PL bundle to the articular cartilage were measured. Radiographic analyses were performed using the techniques of Bernard and Hertel at the femur as well as the method by Stäubli and Rauschning at the tibia.

RESULTS

The center of the AM bundle was at a point 5.3 mm ( +/- 0.7) from the roof of the notch and 5.7 mm ( +/- 0.5) from the intercondylar line. The center of the PL bundle is located at 6.5 mm from the shallow cartilage margin and 5.8 mm from the inferior cartilage margin. On the tibia, the center of the AM bundle is aligned with the anterior horn of the lateral meniscus, while the center of the PL bundle was located 11.2 mm ( +/- 1.2) posterior and 4.1 mm ( +/- 0.6) medial to the anterior insertion of the lateral meniscus. Radiographically, the center of the PL bundle is anterior along Blumensaat's line and lower in the femoral notch along the height of the condyles than the center of the AM bundle. At the tibia, the center of the AM bundle is at 30% and the PL bundle is located at 44% using the method of Stäubli and Rauschning.

CONCLUSION

The center of the femoral PL bundle is shallow and inferior to the AM bundle. On the tibia, the AM bundle lies anterior when compared with the typical single-bundle ACL tunnel that reflects the PL bundle.

CLINICAL RELEVANCE

To imitate the anatomy of the intact ACL, it is mandatory to place the tunnels exactly within the femoral origin and tibial insertion of the ACL.

Results of revision anterior cruciate ligament surgery

BACKGROUND

Revision anterior cruciate ligament surgery remains challenging.

PURPOSE

To analyze the authors' experience with revision anterior cruciate ligament surgery and determine the association between stability and functional results.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between 1991 and 2002, 95 of 102 patients who underwent revision anterior cruciate ligament reconstruction at the authors' institution met the criteria for inclusion in the study. Of those, the 63 (66%) who returned for complete clinical and radiologic evaluation (mean follow-up, 72.7 months) formed the study group. Subjective evaluation focused on return to sports, arthritic symptoms, and subjective International Knee Documentation Committee criteria. Clinical evaluation included examination, KT-1000 arthrometer and functional testing, and radiographic analysis of alignment and arthritis.

RESULTS

Based on International Knee Documentation Committee subjective scores and return to sports, results were rated as excellent/good in 45 patients (71%), fair in 6 (10%), and poor in 12 (19%). A grade IA or IIA Lachman and a KT-1000 arthrometer side-to-side difference of <3 mm (32/63 patients) was associated with a good/excellent result (P < .05). The mechanical axis was midline in 78% (49/63 patients). Radiographic arthritis (16 patients, 25%) was associated with duration of instability after primary failure (P < .03). Return to sports occurred in 59% (37/63 patients). Sixteen patients (25%) required a second revision surgery.

CONCLUSION

Revision anterior cruciate ligament surgery allowed approximately 60% of patients to go back to sports, most of them at lower levels than their prerevision function. Instrumented laxity of <3 mm was associated with a better result. Radiographic arthritis was associated with duration of instability symptoms after primary failure. Patients who undergo revision anterior cruciate ligament surgery should be counseled as to the expected outcome and cautioned that this procedure probably represents a salvage situation and may not allow them to return to their desired levels of function.

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.

Anatomic double-bundle anterior cruciate ligament reconstruction revision surgery

With the increasing number of double-bundle anterior cruciate ligament (ACL) reconstructions being performed, revision cases are expected. This report describes the first 3 cases of revision double-bundle ACL surgeries performed at our institution. In 3 athletes in whom the ACL was previously reconstructed with an anatomic double-bundle technique, new traumatic events occurred and an ACL retear was diagnosed. In cases 1 and 2 the anteromedial (AM) bundle was completely torn and the posterolateral (PL) bundle was stretched and nonfunctional. In case 1 both bundles were reconstructed via the previous tunnels, and the AM and PL grafts were tensioned at 60 degrees of flexion and full extension, respectively. In case 2 the PL femoral tunnel was posterosuperior to the PL anatomic position. Therefore we drilled a third femoral tunnel and used the previous PL tunnel as our new AM tunnel. In case 3 the rupture pattern presented an intact and functional PL bundle and a midsubstance AM tear. We decided to revise only the AM bundle using the previous AM tunnels, which were anatomically positioned. This report shows that revision of anatomic double-bundle ACL reconstruction is reasonable to accomplish and that the principles of anatomy are essential as a guide to approaching each case.