Endoscopic anterior cruciate ligament reconstruction using a computer-assisted fluoroscopic navigation system

Technology-assisted anterior cruciate ligament reconstruction improves tunnel placement but leads to no change in clinical outcomes: a systematic review and meta-analysis

PURPOSE

To investigate the effect of technology-assisted Anterior Cruciate Ligament Reconstruction (ACLR) on post-operative clinical outcomes and tunnel placement compared to conventional arthroscopic ACLR.

METHODS

CENTRAL, MEDLINE, and Embase were searched from January 2000 to November 17, 2022. Articles were included if there was intraoperative use of computer-assisted navigation, robotics, diagnostic imaging, computer simulations, or 3D printing (3DP). Two reviewers searched, screened, and evaluated the included studies for data quality. Data were abstracted using descriptive statistics and pooled using relative risk ratios (RR) or mean differences (MD), both with 95% confidence intervals (CI), where appropriate.

RESULTS

Eleven studies were included with total 775 patients and majority male participants (70.7%). Ages ranged from 14 to 54 years (391 patients) and follow-up ranged from 12 to 60 months (775 patients). Subjective International Knee Documentation Committee (IKDC) scores increased in the technology-assisted surgery group (473 patients; P = 0.02; MD 1.97, 95% CI 0.27 to 3.66). There was no difference in objective IKDC scores (447 patients; RR 1.02, 95% CI 0.98 to 1.06), Lysholm scores (199 patients; MD 1.14, 95% CI - 1.03 to 3.30) or negative pivot-shift tests (278 patients; RR 1.07, 95% CI 0.97 to 1.18) between the two groups. When using technology-assisted surgery, 6 (351 patients) of 8 (451 patients) studies reported more accurate femoral tunnel placement and 6 (321 patients) of 10 (561 patients) studies reported more accurate tibial tunnel placement in at least one measure. One study (209 patients) demonstrated a significant increase in cost associated with use of computer-assisted navigation (mean 1158€) versus conventional surgery (mean 704€). Of the two studies using 3DP templates, production costs ranging from $10 to $42 USD were cited. There was no difference in adverse events between the two groups.

CONCLUSION

Clinical outcomes do not differ between technology-assisted surgery and conventional surgery. Computer-assisted navigation is more expensive and time consuming while 3DP is inexpensive and does not lead to greater operating times. ACLR tunnels can be more accurately located in radiologically ideal places by using technology, but anatomic placement is still undetermined because of variability and inaccuracy of the evaluation systems utilized.

LEVEL OF EVIDENCE

Level III.

Navigation in anterior cruciate ligament reconstruction: State of the art

Computer navigation (CN) for anterior cruciate ligament (ACL) surgery has been used mainly for two purposes: to enhance the accuracy of tunnel position and to evaluate the kinematics of the ACL reconstruction (ACLR) and the stability achieved by different surgical techniques. Many studies have shown that navigation may improve the accuracy of anatomical tunnel orientation and position during ACL reconstructive surgery compared with normal arthroscopic tunnel placement, especially regarding the femoral side. At the same time, it has become the gold-standard method for intraoperative knee kinematic assessment, as it permits a quantitative multidirectional knee joint laxity evaluation. CN in ACL surgery has been associated with diverse problems. First, in most optic systems additional skin incisions and drill holes in the femoral bone are required for fixation of a reference frame to the femur. Second, additional radiation exposure and extra medical cost to the patient for preoperative planning are usually needed. Third, CN, due to additional steps, has more opportunities for error during preoperative planning, intraoperative registration, and operation. Fourth, soft tissues, including the skin and subcutaneous tissues, are usually not considered during the preoperative planning, which can be a problem for kinematic and stability assessment. Many studies have concluded that ACLR using a CN system is more expensive than conventional surgery, it adds extra time to the surgery and it is not mitigated by better clinical outcomes. This, combined with costs and invasiveness, has limited the use of CN to research-related cases. Future technology should prioritize less invasive intra-operative surgical navigation.

Computer-assisted navigation in ACL reconstruction improves anatomic tunnel placement with similar clinical outcomes

BACKGROUND

While the use of navigation systems in anterior cruciate ligament (ACL) reconstruction theoretically improves tunnel placement accuracy and clinical outcomes, the existing literature remains inconclusive. We aimed to evaluate the potential benefits of navigated ACL reconstruction on tunnel placement and clinical outcomes.

METHODS

In this retrospective study, we evaluated a cohort of patients who underwent conventional or navigated (OrthoPilot system) primary ACL reconstruction at our institution from June 2004 to October 2009. Anteroposterior and lateral radiographic knee assessments were evaluated to assess postoperative tunnel positioning. Clinical outcomes, including the International Knee Documentation Committee classification, Lysholm score, and Tegner score, were evaluated preoperatively and 1-year postoperatively. Radiographic and clinical outcomes were compared and analysed using independent 2-sample t-tests and Chi-square tests.

RESULTS

Sixty patients met the inclusion criteria and were included for analysis, comprising of 26 navigated and 34 conventional reconstructions. Postoperative radiographs showed no differences in tibial tunnel position between both groups, but a significantly smaller deviation from the recommended position in the navigated group (navigated: 5.96 %; conventional: 7.92 %; p = 0.008). Femoral tunnel placements in the navigated group were significantly more perpendicularly away from the Blumensaat line (navigated: 38.90 %; conventional: 31.94 %; p = 0.001), with a greater deviation from recommended position (navigated: 11.00 %; conventional: 6.94 %; p = 0.009). There were no differences in 1-year postoperative clinical outcomes (p > 0.05).

CONCLUSION

Navigated ACL reconstruction resulted in a more anatomic femoral tunnel placement and similar clinical outcomes as conventional reconstruction. Further research should be conducted to clarify the potential biomechanical and clinical impacts of navigated ACL reconstruction.

Validation of the registration accuracy of navigation-assisted arthroscopic débridement for elbow osteoarthritis

BACKGROUND

The identification and precise removal of bony impingement lesions during arthroscopic débridement arthroplasty for elbow osteoarthritis is technically difficult. Surgical navigation systems, combined with preoperative 3-dimensional (3D) assessment of bony impingements, can provide real-time tracking of the surgical instruments and impingement lesions. This study aims to determine the registration accuracy of the navigation system for the humerus and ulna during elbow arthroscopy.

METHODS

We tested the registration procedure using resin bone models of 3 actual patients with elbow osteoarthritis. We digitized bone surface points using navigation pointers under arthroscopy. We initially performed paired-point registration, digitizing 6 preset anatomical landmarks, and then refined the initial alignment with surface matching registration, digitizing 30 points. The registration accuracy for each trial was evaluated as the mean target registration error in each reference marker. Three observers repeated the registration procedure 5 times each with the 3 specimens (total, 45 trials). The median of the registration accuracy was evaluated in total (45 trials) as the accuracy of the registration procedure. The differences in the registration accuracy among the 3 observers (median of 15 trials) were also examined.

RESULTS

The total registration accuracies were 0.96 mm for the humerus and 0.85 mm for the ulna. No significant differences were found in the registration accuracy for the humerus and ulna among the 3 observers.

CONCLUSIONS

This arthroscopic-assisted registration procedure is sufficiently feasible and accurate for application of the navigation system to arthroscopic débridement arthroplasty in clinical settings.

The effect of intraoperative fluoroscopy on the accuracy of femoral tunnel placement in single-bundle anatomic ACL reconstruction

PURPOSE

The purpose of the current study was to investigate the potential effect of intraoperative fluoroscopy on the accuracy of femoral tunnel placement in anatomic ACL reconstruction, using an ideal anatomic point as reference and evaluating postoperative tunnel placement based on 3D CT.

METHODS

An experienced ACL surgeon, using the anatomic approach for femoral tunnel placement, relying on intraarticular landmarks and remnants of the torn ACL-and novel to the fluoroscopic assist-was introduced to its use. A prospective series of patients was included where group 1 (without fluoroscopy) and group 2 (with fluoroscopy) both had postoperative CT scans so that femoral tunnel position could be evaluated and compared to an ideal tunnel centre based on anatomic studies by using the Bernard and Hertel grid.

RESULTS

Group 2, where fluoroscopy was used, had a mean femoral tunnel that was closer to the ideal anatomic centre than group 1. In the Bernard and Hertel grid, the distance in the high-low axis (y-axis) was found significantly closer (P = 0.001), whilst the deep-shallow axis (x-axis) and a total absolute distance were not significantly closer to the ideal described anatomic centre.

CONCLUSIONS

Intraoperative fluoroscopy was found effective as an aid for placing the femoral tunnel in a more accurate position, as compared to a desired anatomic centre. Although the concept of the "one-size-fits-all" approach for tunnel placement is debatable, the avoidance of grossly misplaced tunnels is the benefit of using fluoroscopy during ACL reconstruction. The authors hold that fluoroscopy is readily available, safe and easy to use and therefore a good aid in the anatomic approach for graft tunnel placement, for example, in a learning situation, in revision cases and when performing low volumes of such surgery.

LEVEL OF EVIDENCE

III.

Current use of navigation system in ACL surgery: a historical review

PURPOSE

The present review aims to analyse the available literature regarding the use of navigation systems in ACL reconstructive surgery underling the evolution during the years.

METHODS

A research of indexed scientific papers was performed on PubMed and Cochrane Library database. The research was performed in December 2015 with no publication year restriction. Only English-written papers and related to the terms ACL, NAVIGATION, CAOS and CAS were considered. Two reviewers independently selected only those manuscripts that presented at least the application of navigation system for ACL reconstructive surgery.

RESULTS

One hundred and forty-six of 394 articles were finally selected. In this analysis, it was possible to review the main uses of navigation system in ACL surgery including tunnel positioning for primary and revision surgery and kinematic assessment of knee laxity before and after different surgical procedures. In the early years, until 2006, navigation system was mainly used to improve tunnel positioning, but since the last decade, this tool has been principally used for kinematics evaluation. Increased accuracy of tunnel placement was observed using navigation surgery, especially, regarding femoral, 42 of 146 articles used navigation to guide tunnel positioning. During the following years, 82 of 146 articles have used navigation system to evaluate intraoperative knee kinematic. In particular, the importance of controlling rotatory laxity to achieve better surgical outcomes has been underlined.

CONLUSIONS

Several applications have been described and despite the contribution of navigation systems, its potential uses and theoretical advantages, there are still controversies about its clinical benefit. The present papers summarize the most relevant studies that have used navigation system in ACL reconstruction. In particular, the analysis identified four main applications of the navigation systems during ACL reconstructive surgery have been identified: (1) technical assistance for tunnel placement; (2) improvement in knowledge of the kinematic behaviour of ACL and other structures; (3) comparison of effectiveness of different surgical techniques in controlling laxities; (4) navigation system performance to improve the outcomes of ACL reconstruction and cost-effectiveness.

LEVEL OF EVIDENCE

IV.

Variability of tunnel positioning in fluoroscopic-assisted ACL reconstruction

PURPOSE

Intraoperative fluoroscopy has been proposed as a feasible method to improve the accuracy of anatomical tunnel positioning. However, it has so far not been determined, whether this technique reduces the variability of tunnel positioning in a clinical set-up. Therefore, the purpose of this study was to determine the variability of tunnel positions applying intraoperative fluoroscopy.

METHODS

Femoral and tibial tunnel positions of 112 fluoroscopic ACL reconstruction cases were determined according to validated radiological measurement methods. Mean positions, standard deviations and ranges were calculated to determine the variability of the tunnel positions. Subgroup variability analysis was performed to analyse cases in which tunnel positions were corrected.

RESULTS

Applying intraoperative fluoroscopy, the variability of tunnel positions was found to be 3 % at the femur (range 15.4 %) and 2.3 % at the tibia (9.7 %). In 34 cases (30.0 %), non-satisfactory tunnel positions were identified and could be corrected achieving more accurate positions regarding to radiological parameters (14× femur, 16× tibia, 4× femur and tibia).

CONCLUSIONS

The results of the presented study indicate that intraoperative fluoroscopy allows to identify non-accurate tunnel positions regarding to radiological criteria. The determined low variability indicates that fluoroscopic-based ACL reconstruction can be recommended as a feasible, easy and effective adjunct that enables surgeons to create more consistent and reliable tunnel positions in ACL reconstruction.

LEVEL OF EVIDENCE

IV.

Computer-assisted anterior cruciate ligament reconstruction. Four generations of development and usage

The purpose of this paper is to review the literature about the contribution of navigation in anterior cruciate ligament (ACL) reconstruction. The evolution of computer-assisted surgery (CAS) for ACL reconstruction has undergone several steps. These steps were divided into 4 subsequent developments: (1) positioning of ACL graft placement; (2) laxity measurement of ACL reconstruction (quality control); (3) kinematic evaluation during ACL reconstruction (navigated pivot shift); (4) case-specific individual ACL reconstruction with adjustments and additional reconstruction options. CAS has shown to improve femoral tunnel positioning, even if clinical outcomes do not improve results of manual techniques. CAS technology has helped researchers better understand the effects of different ACL reconstruction techniques and bundles replacements on joint laxity and to describe tunnel positioning in relation to native ACL insertion. CAS in ACL surgery can improve results at time zero and can improve knowledge in this field.

Computer-assisted navigation in ACL reconstruction is attractive but not yet cost efficient

PURPOSE

Conventional reconstruction of the anterior cruciate ligament (ACL) has a high success rate. Computer-assisted navigation systems (CANSs) have been developed to further improve the accuracy of tunnel positioning. What is the economic impact from the hospital perspective?

METHODS

Patients having a first ACL reconstruction procedure were included in a prospective multicentre open controlled study comparing two groups: CANS versus conventional surgery. The primary clinical efficacy criterion was the objective International Knee Documentation Committee score at 1-2-year follow-up. Costs were collected retrospectively nationwide.

RESULTS

No significant differences were found for the clinical effectiveness between conventional surgery (100 patients) and CANS (114 patients) at follow-up: ORadjusted 1.01 [0.36-2.84] (n.s). Junior surgeons achieved a significant mean decrease in operating time during the study period: 30 % in the CANS group compared with 10 % in the control group (p < 0.01). The average cost of surgery was 704<euro> for the control group and 1,158<euro> for the CANS group (p < 0.01). The cost of the operating room accounts for >70 % of the total cost. The surgeon's status and the technical CANS learning effect influenced this cost. The cost differential between the two groups decreased with 'CANS' expertise: 238<euro> and 271<euro> in 'expert' centres versus 427<euro> to 731<euro> in other centres.

CONCLUSION

While our study demonstrates the feasibility and the potential interest of CANS for training in ACL reconstruction, from a hospital perspective it is not cost efficient at present.

LEVEL OF EVIDENCE

Economic and decision analysis-developing an economic or decision model, Level II.

Evaluation of a computer-assisted navigation system for anterior cruciate ligament reconstruction: prospective non-randomized cohort study versus conventional surgery

BACKGROUND

Conventional reconstruction of the anterior cruciate ligament (ACL) is associated with a 15% failure rate. Computer-assisted navigation systems (CANS) have been developed to improve the accuracy of tunnel positioning.

HYPOTHESIS

The use of a CANS for ACL reconstruction decreases the rate of failure, defined as IKDC grade C or D, compared to conventional ACL reconstruction.

MATERIALS AND METHODS

This prospective multicentre observational non-randomised open study compared two groups of patients requiring arthroscopic ACL reconstruction: one group was managed with a CANS and the other (control group) without a CANS. The primary evaluation criterion was based on the subjective and objective IKDC scores. Inclusion criteria were age older than 18 years and first ACL reconstruction procedure using autologous semitendinosus and gracilis tendons or an autologous bone-patellar tendon-bone graft. Of the 272 included patients, 214 were analysed; 100 were in the control group and 114 in the CANS group.

RESULTS

No significant between-group differences were found for the fraction of patients having an IKDC grade A or B (P=0.953), the subjective IKDC score (P=0.77), differential knee laxity at 150 N (1.38 ± 1.79 mm in the control group and 1.77 ± 2.06 mmin the CANS group, P=0.384), graft-type, or graft positioning.

DISCUSSION

Our results establish the large-scale feasibility of computer-assisted navigation for ACL reconstruction. However, the main outcomes at 1 year showed no significant differences between patients managed with and without computer-assisted navigation.

The relationship of anterior and rotatory laxity between surgical navigation and clinical outcome after ACL reconstruction

PURPOSE

Recently, a computer-assisted navigation system has been used for the quantitative evaluation not only of anterior-posterior (AP) laxity but also rotational laxity of the tibia intraoperatively. The purpose of this study was to investigate how intraoperative AP or rotational laxities measured by the navigation system could correlate with postoperative AP and rotational laxities of the patients.

METHODS

125 patients who underwent primary isolated anatomical single- or double-bundle ACL reconstruction or augmentation using multistranded autologous hamstring tendons were included in the study after a minimum of 2-year follow-up. Clinically, absolute value and side-to-side difference (SSD) of AP translation of the tibia were measured by KT-2000 preoperatively and postoperatively. Intraoperative measurement of AP translation of the tibia and total range of tibial rotation of the ACL-injured knee were carried out using the computer-assisted navigation system. We have investigated the relationship between intraoperative measurements using the navigation system and AP laxity measurements using the KT-2000 knee arthrometer as well as rotational laxity measurements using the manual pivot shift test.

RESULTS

There was a positive correlation between the SSD of preoperative AP translation of the tibia measured by KT-2000 arthrometer and the reduction in AP laxity following ACL reconstruction measured by the navigation system. However, we found no significant correlation between the reduction in AP laxity measured by the navigation system and the SSD of AP translation of the tibia measured by the KT-2000 arthrometer at final follow-up. Postoperatively, eight patients had a positive pivot shift test. Using the navigation system pre- and post-ACL reconstruction, these patients could not be identified by high absolute values for AP laxity nor rotational laxity.

CONCLUSION

Although AP and rotational laxities vary largely among the patients, and AP and rotational stabilization are successfully achieved immediately after ACL reconstruction, intraoperative AP and rotational laxity measured by the navigation system did not influence the postoperative AP and rotational laxities after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Development of a femoral template for computer-assisted tunnel placement in anatomical double-bundle ACL reconstruction

Femoral graft placement is an important factor in the success of anterior cruciate ligament (ACL) reconstruction. In addition to improving the accuracy of femoral tunnel placement, Computer Assisted Surgery (CAS) can be used to determine the anatomic location. This is achieved by using a 3D femoral template which indicates the position of the anatomical ACL center based on endoscopically measurable landmarks. This study describes the development and application of this method. The template is generated through statistical shape analysis of the ACL insertion, with respect to the anteromedial (AM) and posterolateral (PL) bundles. The ligament insertion data, together with the osteocartilage edge on the lateral notch, were mapped onto a cylinder fitted to the intercondylar notch surface (n = 33). Anatomic variation, in terms of standard variation of the positions of the ligament centers in the template, was within 2.2 mm. The resulting template was programmed in a computer-assisted navigation system for ACL replacement and its accuracy and precision were determined on 31 femora. It was found that with the navigation system the AM and PL tunnels could be positioned with an accuracy of 2.5 mm relative to the anatomic insertion centers; the precision was 2.4 mm. This system consists of a template that can easily be implemented in 3D computer navigation software. Requiring no preoperative images and planning, the system provides adequate accuracy and precision to position the entrance of the femoral tunnels for anatomical single- or double-bundle ACL reconstruction.

Comparison between clinical grading and navigation data of knee laxity in ACL-deficient knees

Background

The latest version of the navigation system for anterior cruciate ligament (ACL) reconstruction has the supplementary ability to assess knee stability before and after ACL reconstruction. In this study, we compared navigation data between clinical grades in ACL-deficient knees and also analyzed correlation between clinical grading and navigation data.

Methods

150 ACL deficient knees that received primary ACL reconstruction using an image-free navigation system were included. For clinical evaluation, the Lachman, anterior drawer, and pivot shift tests were performed under general anesthesia and were graded by an examiner. For the assessment of knee stability using the navigation system, manual tests were performed again before ACL reconstruction. Navigation data were recorded as anteroposterior (AP) displacement of the tibia for the Lachman and anterior drawer tests, and both AP displacement and tibial rotation for the pivot shift test.

Results

Navigation data of each clinical grade were as follows; Lachman test grade 1+: 10.0 mm, grade 2+: 13.2 ± 3.1 mm, grade 3+: 14.5 ± 3.3 mm, anterior drawer test grade 1+: 6.8 ± 1.4 mm, grade 2+: 7.4 ± 1.8 mm, grade 3+: 9.1 ± 2.3 mm, pivot shift test grade 1+: 3.9 ± 1.8 mm/21.5° ± 7.8°, grade 2+: 4.8 ± 2.1 mm/21.8° ± 7.1°, and grade 3+: 6.0 ± 3.2 mm/21.1° ± 7.1°. There were positive correlations between clinical grading and AP displacement in the Lachman, and anterior drawer tests. Although positive correlations between clinical grading and AP displacement in pivot shift test were found, there were no correlations between clinical grading and tibial rotation in pivot shift test.

Conclusions

In response to AP force, the navigation system can provide the surgeon with correct objective data for knee laxity in ACL deficient knees. During the pivot shift test, physicians may grade according to the displacement of the tibia, rather than rotation.

Computer-assisted anterior cruciate ligament reconstruction: an evidence-based approach of the first 15 years

In the last 15 years, computer-assisted surgery (CAS) has been used for many purposes during anterior cruciate ligament (ACL) reconstruction, such as tunnel positioning, joint laxity evaluation, and biomechanical studies. This article is an evidence-based literature review of the contribution of such technology to ACL surgery. A search of the PubMed and Medline databases was performed. Articles were classified according to the study design and to the research topic: anatomy, laxity, kinematics, and comparison of surgical techniques. An evidence-based approach was used to verify the clinical usefulness of CAS to ACL surgery. The use of CAS for research purposes was also evaluated. CAS was shown to improve femoral tunnel positioning, even if clinical outcomes showed no differences compared with manual techniques. CAS technology was found to be useful for research purposes in terms of providing a better comprehension of the effect of different ACL reconstructions and of the different bundles on joint laxity, as well as describing tunnel positioning in relation to native ACL insertion. CAS in ACL surgery can improve results at time 0 and can improve knowledge about ACL anatomy and kinematics. Its application remains limited mostly to research purposes because of the invasiveness of the system and the absence of improved clinical results at follow-up.

Navigation evaluation of the pivot-shift phenomenon during double-bundle anterior cruciate ligament reconstruction: is the posterolateral bundle more important?

PURPOSE

The purpose of this study was to assess the pivot-shift phenomenon during double-bundle anterior cruciate ligament (ACL) reconstruction using a navigation system.

METHODS

Ninety patients who received navigated double-bundle ACL reconstruction were included in this study. The mean age of the patients was 21.9 years. During reconstruction, pivot-shift tests were performed 4 times: before reconstruction, after the posterolateral bundle fixation, after the anteromedial bundle fixation, and after the double-bundle reconstruction. Both tibial internal rotation and anterior translation under the pivot-shift test were measured at each phase by the additional functions of the navigation. The navigation system used in this study was the image-free, which does not require preoperative or intraoperative images, OrthoPilot ACL (version 2.0; B. Braun Aesculap, Tuttlingen, Germany).

RESULTS

Before ACL reconstruction, average (+/- standard deviation) tibial internal rotation and anterior translation under the pivot-shift test were 23.7 degrees +/- 6.1 degrees and 5.2 +/- 2.4 mm. They were significantly decreased to 20.9 degrees +/- 6.4 degrees and 2.3 +/- 1.1 mm after the posterolateral bundle fixation, and also decreased to 22.2 degrees +/- 5.7 degrees and 2.4 +/- 1.1 mm after the anteromedial bundle fixation. There was no significant difference between the groups. After double-bundle reconstruction, they improved to 20.3 degrees +/- 6.3 degrees and 2.0 +/- 1.0 mm.

CONCLUSIONS

Our results indicate that both the posterolateral and the anteromedial bundle similarly control both anterior translation and internal rotation during pivot-shift testing. Double-bundle reconstruction may further improve knee stability.

LEVEL OF EVIDENCE

Level II, development of diagnostic criteria on basis of consecutive patients with universally applied reference gold standard.

Does the use of fluoroscopy and isometry during anterior cruciate ligament reconstruction affect surgical decision making?

OBJECTIVE

Poor results after anterior cruciate ligament (ACL) reconstruction are often due to inaccurate graft placement. Numerous strategies have been advocated to improve accuracy and consistency of tunnel positioning, including computer-assisted navigation. Less expensive alternatives, such as intraoperative fluoroscopy and isometry, have also been advocated for confirming guide pin placement before reaming the femoral tunnel. It is unknown how often these techniques cause surgeons to change the location of their femoral tunnel at the time of surgery. We undertook this study to determine how often this approach results in repositioning of the guide pin before final graft placement. We hypothesized that a lower level of surgeon experience would lead to a higher frequency of repositioning compared to a higher level of experience.

DESIGN

Prospective, case series.

SETTING

Institutional.

PATIENTS

Intraoperative data were gathered prospectively from 413 consecutive, primary ACL reconstructions performed by the sports medicine group at our institution. Of the 413 procedures enrolled in this study, 407 were available for analysis. Six procedures were excluded because the tension isometer was unavailable during the procedure.

INTERVENTIONS

Isometry and fluoroscopy were used in all cases to aid in the accurate placement of the femoral tunnel. Femoral pin change based on the results of isometry or fluoroscopy was recorded. The percentage of cases involving a change in the femoral pin resulting from the use of these techniques was calculated. This percentage was also calculated separately for cases performed by a staff surgeon (fellowship-trained sports medicine staff) as well as less experienced surgeons (current sports medicine fellows).

MAIN OUTCOME MEASURES

The main outcome measurement was whether the femoral pin was changed.

RESULTS

Of the 407 procedures available for review, 62 (15%) of them involved a change in femoral pin position secondary to information provided by intraoperative isometry or fluoroscopy. In the procedures performed by more experienced surgeons, the pin was changed in 40 (16%) of 253 cases; in those performed by less experienced surgeons, it was changed in 22 (14%) of 154 cases.

CONCLUSIONS

The intraoperative use of isometry and fluoroscopy during ACL reconstruction led to changes in the femoral tunnel placement 15% of the time. The influence of these instruments on intraoperative decision making does not seem to diminish with surgical experience.

Intraoperative biomechanical evaluation of anatomic anterior cruciate ligament reconstruction using a navigation system: comparison of hamstring tendon and bone-patellar tendon-bone graft

BACKGROUND

Recently, more anatomic anterior cruciate ligament reconstructions have been developed to improve knee laxity.

PURPOSE

The objective of this study is to assess knee kinematics after double-bundle reconstruction with hamstring tendon and after anatomically oriented reconstruction with a patellar tendon using navigation during surgery.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Eighty knees received double-bundle reconstruction with a hamstring tendon graft, and 45 knees received anatomically oriented reconstruction with a patellar tendon graft. Before reconstruction, knee laxity was measured using a navigation system. After the posterolateral bundle or anteromedial bundle was temporarily fixed during double-bundle reconstruction, knee laxity was measured to assess the function of each bundle. After double-bundle reconstruction or anatomically oriented reconstruction with patellar tendon, knee laxity was measured in the same manner.

RESULTS

Both double-bundle reconstruction and anatomically oriented reconstruction similarly improved knee laxity compared with before reconstruction in all knee flexion angles. Regarding the function of the anteromedial and posterolateral bundles in double-bundle reconstruction, the 2 grafts showed contrasting behavior. The posterolateral bundle restrained tibial displacement mainly in knee extension, whereas the anteromedial bundle restrained it more in the knee flexion position. The posterolateral bundle has a more important role in controlling rotation of the tibia than the anteromedial bundle.

CONCLUSION

Although the posterolateral bundle has an important role in the extension position, the anteromedial bundle is more important in the flexion position. Therefore, both bundles should be reconstructed to improve knee laxity throughout knee range of motion. Even with single-bundle reconstruction using a patellar tendon, anatomic reconstruction might improve knee laxity similar to double-bundle reconstruction.

Outcomes after conventional versus computer-navigated anterior cruciate ligament reconstruction

PURPOSE

The purpose of this prospective randomized study was to assess biomechanical, radiographic, and functional results after single-bundle anterior cruciate ligament (ACL) reconstruction by use of a navigation system.

METHODS

ACL reconstruction was performed by use of the OrthoPilot navigation system (B. Braun-Aesculap, Tuttlingen, Germany) in 40 patients (group 1); and in another 40 patients, surgery was done by the standard manual targeting technique (group 2). The anterior laxity was measured with a KT-1000 arthrometer (MEDmetric, San Diego, CA). Femoral and tibial tunnel position was evaluated radiologically according to the method described by Bernard and Hertel and by Harner et al., respectively. The questionnaire-based Lysholm and International Knee Documentation Committee scales were included to compare the functional state in both groups.

RESULTS

The knees in group 1 were as stable as those in group 2 during the arthrometer testing, with a lower value of dispersion. The postoperative Lysholm and International Knee Documentation Committee scores had the same value in both groups. Statistical differences existed with regard to anterior-posterior femoral tunnel placement when the navigated and standard techniques were compared; in the navigated group, more exact results were found. No significant complications were observed.

CONCLUSIONS

The only difference that we found between the navigated and standard groups was in radiographic tunnel position measurement. The computer-assisted navigation technique in our study resulted in more accurate tunnel placement in the femur (but not the tibia) than the traditional arthroscopic technique. However, the performed standard radiographic measurements are of limited precision in principle. Functional scales and stability tests gave similar results in both groups.

LEVEL OF EVIDENCE

Level I, therapeutic study.