Radiographic analysis of femoral interference screw placement during ACL reconstruction: endoscopic versus open technique

Analysis of the Mechanical Behavior of Porcine Graft Fixation in a Polyurethane Block Using a 3D-printed PLA Interference Screw

Objective  The interest in using 3D printing in the healthcare field has grown over the years, given its advantages and potential in the rapid manufacturing of personalized devices and implants with complex geometries. Thus, the aim of the present study was to compare the mechanical fixation behavior of a 3D-printed interference screw, produced by fused deposition modeling of polylactic acid (PLA) filament, with that of a titanium interference screw. Methods  Eight deep flexor porcine tendons, approximately 8 mm wide and 9 cm long, were used as graft and fixed to a 40 pounds-per-cubic-foot (PCF) polyurethane block at each of its extremities. One group was fixed only with titanium interference screws (group 1) and the other only with 3D-printed PLA screws (BR 20 2021 018283-6 U2) (group 2). The tests were conducted using an EMIC DL 10000 electromechanical universal testing machine in axial traction mode. Results  Group 1 (titanium) obtained peak force of 200 ± 7 N, with mean graft deformation of 8 ± 2 mm, and group 2 (PLA) obtained peak force of 300 ± 30 N, and mean graft deformation of 7 ± 3 mm. Both the titanium and PLA screws provided good graft fixation in the polyurethane block, with no slippage or apparent deformation. In all the samples, the test culminated in graft rupture, with around 20 mm of deformation in relation to the initial length. Conclusion  The 3D-printed PLA screw provided good fixation, similar to that of its titanium counterpart, producing satisfactory and promising results.

[Progress of different methods for femoral tunnel positioning in anterior cruciate ligament reconstruction]

OBJECTIVE

To systematically review the progress of different methods for femoral tunnel positioning in anterior cruciate ligament (ACL) reconstruction and provide a clinical reference for treatment of ACL rupture.

METHODS

The literature about the femoral tunnel positioning in ACL reconstruction was widely reviewed. The advantages and disadvantages and the clinical results of each method were summarized.

RESULTS

Currently in ACL reconstruction, methods for femoral tunnel positioning include transtibial technique (TT), anteromedial technique (AM), outside-in (OI), modified TT (mTT), and computer assisted surgery. There is no significant difference in the postoperative effectiveness between TT technique and AM technique. Compared with the TT technique, the OI technique has higher rotational stability of knee, but there is no significant difference in clinical results. The femoral tunnel located by mTT technique is closer to the anatomical placement than that of TT technique, but mTT technique is not effective for systematically anatomic femoral tunnel positioning, and further research is needed to prove its advantages.

CONCLUSION

Different femoral tunnel positioning methods have their own advantages and disadvantages, and there is no definite evidence that one is superior than the rest.

Hyperflexion and Femoral Interference Screw Insertion in ACL Reconstruction

Background:

In anatomic anterior cruciate ligament (ACL) reconstructions produced with flexible reamers and no knee hyperflexion, it is unknown whether knee hyperflexion is necessary for femoral interference screw insertion.

Purpose:

To compare femoral screw-graft divergence in anatomic ACL reconstructions with endoscopic interference screws placed without knee hyperflexion and with the use of flexible versus rigid screwdrivers.

Study Design:

Controlled laboratory study.

Methods:

Ten matched pairs of cadaveric knees had bone-tendon-bone graft ACL reconstructions with anatomic femoral tunnels. The knees were flexed to 90°. Femoral interference screws (7 × 20 mm) were placed in pairs of knees: in 1 knee with a flexible screwdriver and in the opposite knee with a rigid screwdriver. Graft-screw divergence was imaged with computed tomography scans and tested with cyclic and static biomechanical tests.

Results:

The mean screw-graft divergence was 12.07° ± 4.04° with the rigid screwdriver and 10.68° ± 3.23° with the flexible screwdriver (P = .35). The cyclic tests with screws placed by a rigid screwdriver had a mean increase in displacement of 0.56 ± 0.20 mm. For screws placed with the flexible screwdriver, the mean increase in displacement was 0.58 ± 0.32 mm (P = .66). Yield load was 393.3 ± 95.1 N for screws placed by a rigid screwdriver and 408.2 ± 119.0 N for screws inserted with the flexible screwdriver (P = .78). Maximum load was 523.1 ± 88.7 N for screws placed by a rigid screwdriver and 467.1 ± 107.3 N for screws inserted with the flexible screwdriver (P = .09).

Conclusion:

With either a rigid or a flexible screwdriver, there were no significant effects on screw divergence or fixation strength.

Clinical Relevance:

Knees can be kept at 90° during endoscopic femoral interference screw insertion. The use of a traditional rigid or flexible screwdriver will not affect screw-graft divergence or fixation strength.

Editorial Commentary: In 2016 Divergence Goes Beyond the United States 2-Party System: Interference Screw Divergence in Anterior Cruciate Ligament Reconstruction of the Knee Revisited

As a result of emerging technology and techniques developed for anterior cruciate ligament (ACL) reconstruction, it is important to evaluate all aspects of the new procedures. One of these hot topics is retrograde drilling, which leads to inside-out ACL interference screw divergence from ACL sockets created from outside-in. In this paper, the authors look at screw divergence in the femoral tunnel for bone-patella-bone reconstructions performed with an outside-in retrograde drill. The screws are inserted through a separate accessory anterior medial portal, and therefore there is concern on whether or not there is significant divergence compromising their fixation. This study supports the use of this technique with clinically acceptable divergence.

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.

RADIOLOGICAL ANALYSIS OF BONE TUNNEL POSITION IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION SURGERY: COMPARISON BETWEEN THE OPEN TECHNIQUE AND ARTHROSCOPY VIA AN ANTEROMEDIAL PORTAL

Objectives: To evaluate and compare bone tunnel positioning in anterior cruciate ligament (ACL) reconstruction surgery using the arthroscopic technique and the open technique consisting of arthrotomy. Method: A comparative retrospective study on 70 patients with ACL lesions was conducted. Thirty-five patients underwent ACL reconstruction by means of the open technique and 35 by means of the arthroscopic technique using an anteromedial portal. All the patients underwent ACL reconstruction using an autologous graft from the middle third of the patellar tendon, fixed using interference screws. The postoperative radiographs were reviewed and the positioning of the femoral tunnel was evaluated using the methods proposed by Harner et al. and Aglietti et al., while the tibial tunnel was assessed using the method proposed by Rauschning and Stäubli. Results: Fifty-four of the patients were male and 16 were female. Their mean age at the time of the procedure was 34 years and 3 months, with a range from 17 to 58 years. The arthroscopic technique was shown to be more accurate than the open technique for positioning both the femoral and the tibial bone tunnels. Conclusions: Radiological analysis on the knees subjected to ACL reconstruction showed that the positioning of both the femoral and the tibial bone tunnels presented less variation when the surgery was performed arthroscopically.

Fluoroscopically-assisted hamstring ACL reconstruction

The fluoroscope can be a valuable tool during hamstring ACL reconstruction when appropriate measures are taken to minimize radiation exposure risk to patients and operating room personnel.

Complications of anterior cruciate ligament reconstruction with bone-patellar tendon-bone constructs: care and prevention

Rupture of the anterior cruciate ligament is a common injury. Correct diagnosis and patient selection, along with proper surgical technique, with careful attention to anatomic graft placement, followed by attention to proper rehabilitation, leads to predictably good to excellent results. This article reviews the recognition and avoidance of complications associated with bone-patellar tendon-bone constructs of anterior cruciate ligament reconstruction.

Biomechanics of intratunnel anterior cruciate ligament graft fixation

Interference screw fixation of bone-patellar tendon-bone grafts now is considered the standard against which all ACL graft-fixation techniques are compared, but mechanical fixation of the ACL graft in the bone tunnels is the weak link in the early postoperative period. This article discusses some of the limitations of in vitro biomechanical studies and reviews variables that influence the tensile properties of intratunnel fixation methods for bone-tendon-bone and soft tissue grafts.

The removal of a dislocated femoral interference screw through a posteromedial portal

The intra-articular migration of a femoral interference screw is a rare complication after anterior cruciate ligament (ACL) reconstruction in the knee. Only a few reports of cases have been published within the last few years and different approaches toward this complication have been described. We report the case of a 23-year-old female patient who was admitted with knee pain after undergoing an ACL reconstruction 4 years previously. After the clinical examination, a knee radiograph in 2 planes revealed a dislocated femoral interference screw lying in the popliteal fossa. During arthroscopy, the interference screw was retrieved through an additional posteromedial portal to avoid an arthrotomy. The causes for intra-articular screw migration are multiple and most cases were reported in the early postoperative period. The arthroscopic removal of a screw is recommended because of the lower morbidity.

Treatment of anterior cruciate ligament injuries, part I

Anterior cruciate ligament injuries are common among athletes. Although the true natural history remains unclear, anterior cruciate ligament injuries are functionally disabling; they predispose the knee to subsequent injuries and the early onset of osteoarthritis. This article, the first in a 2-part series, was initiated with the use of the PubMed database and a comprehensive search of articles that appeared between January 1994 to the present, using the keywords anterior cruciate ligament. A total of 3810 citations were identified and reviewed to determine the current state of knowledge about the treatment of these injuries. Articles pertaining to the biomechanical behavior of the anterior cruciate ligament, the prevalence of anterior cruciate ligament injury, the natural history of the anterior cruciate ligament-deficient knee, injuries associated with anterior cruciate ligament disruption, risk factors for anterior cruciate ligament injury, indications for treatment of anterior cruciate ligament injuries, and nonoperative and operative treatments were obtained, reviewed, and served as the basis for part I. Part II, to be presented in another issue of this journal, includes technical aspects of anterior cruciate ligament surgery, bone tunnel widening, graft healing, rehabilitation after reconstruction, and the effect of sex, age, and activity level on the outcome of surgery. Our approach was to build on prior reviews and to provide an overview of the literature for each of the before-mentioned areas of study by summarizing the highest level of scientific evidence available. For the areas that required a descriptive approach to research, we focused on the prospective studies that were available; for the areas that required an experimental approach, we focused on the prospective, randomized controlled trials and, when necessary, the highest level of evidence available. We were surprised to learn that considerable advances have been made during the past decade regarding the treatment of this devastating injury.

Expansion anchors for use in anterior cruciate ligament (ACL) reconstruction: establishing proof of concept in a benchtop analysis

The current method for graft fixation in bone tendon-bone anterior cruciate ligament (ACL) reconstruction is the interference screw. Although this method of fixation provides for adequate graft fixation with respect to strength, intraoperative placement is difficult and the failure rate is high. To address these concerns, we have designed and fabricated prototype expansion anchors that could be expanded to anchor the graft in the bone tunnel. As a first step in assessing the validity of this concept, in the current work, we demonstrate that these systems are of comparable fixation strength (biomechanical pullout testing) to the standard interference screw, are smaller at the time of insertion and thus provide for increased visibility and ease of placement. The increased visibility should result in better placement and reduced failure rates. The increased ease of placement should result in significant savings in decreased OR time.

Biomechanical evaluation of press-fit femoral fixation technique in ACL reconstruction

In this experimental study, the authors evaluated the biomechanical properties of the femoral press-fit graft fixation technique in ACL reconstruction. 20 fresh frozen distal femurs, patellae and patellar ligaments were used from 10 cadaver specimens. Three bone-patellar tendon grafts of 10 mm width were prepared from each sample; altogether 60 bone-patellar tendon grafts were prepared for the experiment. Three 9 mm wide tunnels were drilled in each distal femur at different angles (0, 15, 30, 45, and 60 degrees). This means that 60 tunnels were drilled into the 20 femurs, 12 at each angle. The trapezoid bone blocks were impacted into the holes. The primary stability and stiffness of this press-fit fixation method were measured with a Zwick 020 computer-controlled testing device using maximum-failure tensile-strength tests. The ultimate tensile strength was the greatest at 45 degrees (534+/-20 N, range 507-554), with 118+/-10 N/mm (range 99-126) stiffness, followed by 485+/-35 N (range 416-510) with 122+/-13 N/mm (range 104-136) stiffness at 30 degrees, 353+/-18 N (range 320-371) with 113+/-13 N/mm (range 83-124) stiffness at 15 degrees, and 312+/-30 N (range 261-343) with 89+/-14 N/mm (ranged:68-103) stiffness at 0 degrees. In the cases of 0, 15, 30 and 45 degrees the bone blocks were pulled out of the drilled holes, but at 60 degrees rupture of the patellar tendon or breakage of the bone block occurred more frequently. It can be seen that the ultimate tensile strength increased with the angle between the loading direction and the bone block. When compared to data in the literature, these data showed similar and satisfying biomechanical properties of femoral press-fit fixation. Because of the known advantages of an implantation-free fixation technique, the femoral press-fit fixation technique can be a good alternative in ACL surgery. These results provide the basis for future studies involving the postoperative healing process of this femoral press-fit fixation technique in porcine knees.

Fixation strength of a novel bioabsorbable expansion bolt for patellar tendon bone graft fixation: an experimental study in calf tibial bone

This biomechanical study compares the initial fixation strength of a novel bioabsorbable two-shell expansion bolt (EB) with that of a well-established interference-screw technique in bone-patellar tendon-bone (BPTB) reconstruction in a calf model. Thirty tibia plateaus (age 5-6 months) were assigned to three groups: In groups I and II, trapezoidal bone plugs of BPTB grafts were fixed with bioabsorbable poly-L-lactide interference screws (8 x 23 mm) or titanium interference screws (8 x 25 mm) respectively. In group III, semicircular grafts were fixed using bioabsorbable poly-D, L-lactide expansion bolts (5.8/8.7 x 10 x 35 mm). The tensile axis was parallel to the bone tunnel, and the construction was loaded until failure applying a displacement rate of 1 mm per second. In group II the mean ultimate loads to failure (713 N+/-218 N) were found to be significantly higher than those of groups I (487 N+/-205 N) and III (510 N+/-133 N). Measurement of stiffness showed 45 N/mm+/-13.3 in group I, 58 N/mm+/-17.4 in group II and 46 N/mm+/-6.9 in group III, and did not demonstrate significant differences. We found a correlation between insertion torque and wedge insertion force and ultimate loads to failure in all groups (r=0.53 in group I, r =0.54 in group II, and r =0.57 in group III). Cross-section planes of bone tunnel increased by 51%, 30% and 31% respectively, following insertion of screws or expansion of bolts (p<0.05). We conclude that ACL graft fixation by means of the presented expansion bolt demonstrates a fixation strength similar to the established bioabsorbable screw fixation, and is a reasonable alternative fixation method, especially since some of the specific pitfalls of screw fixation can be avoided.

Transtibial tubercle fixation without hardware for anterior cruciate ligament and posterior cruciate ligament reconstruction: A new technique

Tibial fixation with implants for both anterior and posterior cruciate ligament reconstructions (ACLR and PCLR) can be associated with a wide variety of problems. Common problems encountered include graft-tunnel mismatch when using grafts with bone blocks, graft damage or poor graft fixation using metal or absorbable implants, painful retained hardware requiring removal, and hardware interference during revision surgery. A new technique is presented using transosseous graft suture passage across the tibial tubercle followed by knot tying over a bone bridge. The technique provides a quick, simple, safe, and reproducible alternative for primary or supplemental tibial graft fixation without hardware in ACLR and PCLR.

The use of intraoperative fluoroscopy to reduce femoral interference screw divergence during endoscopic anterior cruciate ligament reconstruction

Femoral interference screw divergence can potentially have detrimental consequences in the rehabilitation of anterior cruciate ligament (ACL) reconstruction. Several biomechanical studies suggest that divergence angles greater than 15 degrees significantly decrease the pullout strength of the graft. Numerous techniques have been described in the literature that address this issue; however, the use of an image intensifier intraoperatively is not frequently discussed. We describe a technique in which fluoroscopy is used to confirm the proper position of the femoral interference screw at the time of the procedure, and therefore minimizes the incidence of significant screw divergence. Radiographic analysis of 62 patients who underwent endoscopic ACL reconstruction using bone-patellar tendon-bone autograft using this technique revealed significant divergence in only 3% of patients.

Anterior cruciate ligament reconstruction the two-incision technique

Historically, the two-incision technique for anterior cruciate ligament (ACL) reconstruction was the standard of practice. It allows predictable, near-anatomic placement of the femoral tunnel and provides highly reproducible results with few complications. There are several major advantages of the two-incision technique over endoscopic methods. These include consistent femoral tunnel placement, elimination of concern for "blowing out the back wall," elimination of the problem of graft-tunnel mismatch, elimination of the problem of screw divergence, and ease of use for revision ACL reconstruction procedures. The angle of the ACL graft is also more anatomic, matching the angle of the native ACL. In this chapter we present our technique for reconstruction of the ACL using the two-incision approach. Indications for its use are discussed. Advantages and disadvantages of the two-incision method compared with the all-endoscopic approach are reviewed.

Rehabilitation after hamstring anterior cruciate ligament reconstruction

A prospective comparative study was conducted involving 62 patients to determine the effects and limits of accelerated rehabilitation on clinical outcome. The study focused on whether aggressive rehabilitation after anterior cruciate ligament reconstruction with the doubled semitendinosus and gracilis tendon autograft results in stretching the graft. Thirty patients had postoperative rehabilitation according to the current conservative protocol, and 32 patients had rehabilitation using an accelerated regime. Each patient was evaluated subjectively and objectively 36 months or more after surgery. Concerning the side-to-side difference in the anterior laxity, 87% of the patients in the conservative rehabilitation group had 3 mm or less and 80% of the patients in the accelerated rehabilitation group had the same acceptable laxity. There was no significant difference between the two groups. Muscle torque was restored significantly earlier in the patients in the accelerated rehabilitation group than in the patients in the conservative rehabilitation group. Nine months after surgery, however, there were no significant differences in the torque between the two groups. Accelerated rehabilitation significantly increased the incidence of knee effusion during rehabilitation. This study showed that acceleration of postoperative rehabilitation could rapidly restore muscle strength without significantly compromising graft stability in anterior cruciate ligament reconstruction with the doubled hamstring tendon autograft. However, this study also showed that acceleration significantly increases the incidence of synovitis. Acceleration of postoperative rehabilitation has advantages and disadvantages for clinical outcome after anterior cruciate ligament reconstruction.

Transcondylar screw fixation in anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to investigate the outcomes of 2 different methods of femoral fixation for arthroscopically assisted anterior cruciate ligament (ACL) reconstruction.

TYPE OF STUDY

Double-blind prospective study.

METHODS

Fifty-five patients were prospectively evaluated at 2-year follow-up. In group A, 24 patients underwent arthroscopic ACL reconstruction with bone-patellar tendon-bone and interference screw fixation. In group B, 31 patients underwent arthroscopic ACL reconstruction with bone-patellar tendon-bone and transcondylar screw fixation. Patients were evaluated by using the IKDC form, Lysholm-II form, Tegner scoring system, and KT-2000 arthrometer.

RESULTS

In group A, final IKDC clinical evaluation achieved 0% grade A, 62.5% grade B, 25% grade C, and 12.5% grade D. In group B, 29.1% achieved grade A, 54.8% grade B, 12.9% grade C, and 3.2% grade D. The difference was statistically significant (P <.05). The injured versus normal side-to-side KT-2000 difference at maximum manual loading was 3.68 mm (SD, 1.71) in group A and 1.64 (SD, 2.05) in group B (P <.0001).

CONCLUSIONS

This prospective study could not provide significant data suggesting that 1 method of fixation is superior to the other. Therefore, we consider both methods comparable in terms of stability and functional outcome at short-term follow-up. Transcondylar fixation offers the following advantages: fixation without intra-articular hardware, greater bone-to-bone fixation, and the possibility of fixation with breakage of the posterior femoral tunnel wall. Moreover, this method may be a useful alternative in revision ACL surgery.

Effects of interference fit screw length on tibial tunnel fixation for anterior cruciate ligament reconstruction

Graft-tunnel mismatch during arthroscopically assisted anterior cruciate ligament reconstruction using the central-third patellar tendon results in less than 20 mm of bone plug remaining in the tibial tunnel. We decided to evaluate the strength of bone plug fixation using interference fit screws that were less than 20 mm in length. Biomechanical testing was performed on 48 porcine hindquarters using 9-mm diameter interference fit screws that measured 12.5, 15, and 20 mm in length. No significant difference was noted between the different-length screws for insertion torque, divergence, stiffness, displacement, or load to failure. We believe, therefore, that comparable graft fixation can be achieved in the tibial tunnel using 9-mm diameter interference fit screws that are less than 20 mm long, and that these shorter screws may be useful in cases of graft-tunnel mismatch.

Practical considerations in anterior cruciate ligament replacement surgery

The endoscopic method of anterior cruciate ligament (ACL) reconstruction using a patellar tendon graft that is secured with interference screws is a commonly performed procedure. It has many potential pitfalls, the majority of which are secondary to technical errors. Prevention of errors starts with a full knowledge of normal ACL anatomy and any discrepancies with the size and shape of the graft substitute. Accurate tibial and femoral tunnel placement is essential and involves using consistent intra-articular landmarks and achieving specific radiographic criteria. Accurate tunnel placement minimizes graft excursion and impingement against the roof of the intercondylar notch. This will result in maximum knee stability and motion. Much has been written about the principles of graft-tunnel mismatch and interference screw-bone plug divergence. The clinical implications of these potential sources of error remain somewhat controversial and are discussed in this article.

Is screw divergence in femoral bone-tendon-bone graft fixation avoidable in anterior cruciate ligament reconstruction using a single-incision technique? A radiographically controlled cadaver study

Interference screw fixation of patellar tendon bone-tendon-bone grafts for anterior cruciate ligament reconstruction has proven to be a method with high pullout strength if screw divergence is avoided. Twenty-four fresh-frozen cadaveric human knees were used to identify the ideal position for a portal and an optimal knee flexion angle to obtain parallel placement of screw and bone block. On all specimens, anterior cruciate ligament reconstruction was performed using a single-incision technique. In the first part of this study, screw placement was analyzed in the frontal plane. In the second part, screw placement was investigated in the sagittal plane, measuring the additional flexion required between femoral tunnel drilling (at 60 degrees of knee flexion) and screw insertion to obtain parallel screw placement. For both part I and II, image intensification was used. In the third part, femoral screw placement was carried out through a paraligamentous approach and with additional flexion of 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, and 60 degrees. This study shows that screw placement with minimal divergence in the frontal and sagittal planes can be achieved by inserting the screw through a nearly central portal and flexing the knee an additional 35 degrees to 40 degrees.

Graft fixation in cruciate ligament reconstruction

Cruciate ligament reconstruction has progressed dramatically in the last 20 years. Anatomic placement of ligament substitutes has fostered rehabilitation efforts that stress immediate and full range of motion, immediate weightbearing, neuromuscular strength and coordination, and early return to athletic competition (3 months). This has placed extreme importance on secure graft fixation at the time of ligament reconstruction. Current ligament substitutes require a bony or soft tissue component to be fixed within a bone tunnel or on the periosteum at a distance from the normal ligament attachment site. Fixation devices have progressed from metal to biodegradable and from far to near-normal native ligament attachment sites. Ideally, the biomechanical properties of the entire graft construct would approach those of the native ligament and facilitate biologic incorporation of the graft. Fixation should be done at the normal anatomic attachment site of the native ligament (aperture fixation) and, over time, allow the biologic return of the histologic transition zone from ligament to fibrocartilage, to calcified fibrocartilage, to bone. The purpose of this article is to review current fixation devices and techniques in cruciate ligament surgery.

Locating femoral graft placement from lateral radiographs in anterior cruciate ligament reconstruction: a comparison of 3 methods of measuring radiographic images

Graft positioning in anterior cruciate ligament (ACL) reconstruction is usually documented from lateral postoperative radiographs. The purpose of this study was to compare 3 measurement methods for femoral graft placement in 50 patients with ACL reconstruction. Intraoperative radiographic images were obtained and divided into 2 groups. The first group showed suboptimal projections, with out-of-plane rotations causing the femoral condyles to not be perfectly overlapped. The second group showed good projection, with optimal rotation and fully overlapped femoral condyles. In our study, only the measurement technique described by Amis produced data with the least measurement error when multiple observers assessed both groups. It is recommended that Amis' method be used to measure femoral ACL graft position so that reliable data are available for comparison between medical centers.

A new bioabsorbable interference screw: preliminary results of a prospective, multicenter, randomized clinical trial

SUMMARY

A randomized clinical trial was conducted to compare a bioabsorbable polyglyconate screw (Endo-Fix; Smith & Nephew, Andover, MA) to a metal screw in anterior cruciate ligament reconstruction. A total of 124 patients were operated on and 113 assessed up to 1 year postoperatively. Assessments included a history and physical examination, the IKDC evaluation, and knee arthrometry measurements. No significant differences were found between the groups with respect to any of the IKDC problem areas at 1 year. The IKDC final evaluation was normal or nearly normal in 92% of polyglyconate patients and 90% of controls. The incidence of postoperative complications was similar in the 2 groups. One polyglyconate patient developed a subcutaneous cyst that may have been related to breakdown of the screw. This resolved without treatment and the patient had an excellent clinical outcome. This study shows that the polyglyconate screw is an effective alternative to metal in endoscopic reconstruction of the ACL.

Comparison of arthroscopic one-incision and two-incision techniques for reconstruction of the anterior cruciate ligament

The purpose of this study was to assess the outcome of arthroscopic anterior cruciate ligament reconstruction performed using either the 'one-incision' technique or the rear-entry 'two-incision' technique. A series of 221 consecutive patients who underwent anterior cruciate ligament reconstruction was reviewed retrospectively. In the study population, two subgroups were defined. Group A consisted of 118 patients who underwent reconstruction using the one-incision transtibial endoscopic technique and Group B consisted of 103 patients who underwent reconstruction using the two-incision technique. The groups were comparable in terms of age, sex and activity level. The follow-up was performed after 47 (40-68) months in Group A and 55 (40-68) months in Group B. The Lysholm score at the final follow-up was significantly lower in Group A (90, 38-100) than in Group B (94, 34-100) (P = 0.002). The median KT-1000 total side-to-side difference was 1.5 (-6 to 7.5) mm in Group A, and 2.0 (-3.5 to 9) mm in Group B (n.s.). No significant difference between the groups was found when the IKDC evaluation system was used. Four intra-operative complications were registered in Group A and none in Group B (P = 0.06). No significant difference was found in terms of anterior knee pain, the one-leg-hop quotient or the activity level at the final follow-up. In this study the two methods gave similar and satisfactory results. Serious intraoperative complications were, however, recorded in four cases when the one-incision technique was used.

Reconstruction of the anterior cruciate ligament: comparison of outside-in and all-inside techniques

The aim of this prospective study was to compare two arthroscopic techniques for reconstructing the anterior cruciate ligament, the "outside-in" (two incisions) and the "all-inside" (one incision) techniques. The results obtained for 30 patients operated on using the "outside-in" technique (group I) were compared with those for 29 patients operated on using the "all-inside" technique (group II). Before surgery, there were no significant differences between the groups in terms of Lysholm score, Tegner activity level, patellofemoral pain score, or knee laxity. Both groups displayed significant improvements in Lysholm score after 24 months, from 69 (16) to 91 (9) in group I and from 70 (17) to 90 (15) in group II (means (SD)). There were also significant improvements in patellofemoral pain scores in both groups, from 13 (6) to 18 (5) in group I and from 14 (6) to 18 (4) in group II after 24 months. No difference was found between the groups in knee stability at the 24 month follow up. The IKDC score was identical in both groups at follow up. The operation took significantly longer for patients in group I (mean 94 (15)) than for those in group II (mean 86 (20)) (p = 0.03). The mean sick leave was 7.7 (6.2) weeks in group I and 12.3 (9.7) weeks in group II (p = 0.026), indicating that there may be a higher morbidity associated with the "all-inside" technique. It can be concluded that there were no significant differences between the two different techniques in terms of functional results, knee laxity, or postoperative complications. The results were satisfactory and the outcome was similar in both treatment groups.

Reduction of femoral interference screw divergence during endoscopic anterior cruciate ligament reconstruction

One of the complications of endoscopic anterior cruciate ligament (ACL) reconstruction is femoral interference screw divergence, usually occurring when the femoral screw insertion is different than the portal used for reaming the femoral tunnel. A new technique using a StraightShot graft passer (DePuy Orthopaedic Technology, Tracy, CA) allows the safe passage of a 7 mm M. Kurosaka Advantage cannulated femoral interference screw (DePuy) through the tibial tunnel with the patella tendon graft fully in position. This study compares femoral interference screw divergence in bone-patellar tendon-bone ACL reconstruction using two different screw insertion portals: the accessory anteromedial patella portal and the tibial tunnel portal (StraightShot technique). A radiographic analysis of 81 consecutive endoscopic ACL reconstructions was performed. The total divergence of each femoral screw was measured on both anteroposterior and lateral radiographs and then combined. Group I had the 7-mm femoral screw inserted through the accessory anteromedial patella portal; group II had the femoral screw inserted directly through the tibial tunnel. Group I showed more than 10 degrees of divergence in 50% of the cases, compared with only 4% percent in group II. The average divergence dropped from 11.3 degrees in group I to 1.2 degrees in group II. Femoral interference screw divergence can be virtually eliminated by inserting the femoral screw directly through the tibial tunnel using the StraightShot technique.

The HAKI technique of femoral interference screw insertion

We describe a simple and reliable technique, the HAKI technique, of femoral interference screw fixation that can reduce surgical complications. In 83 ordinary endoscopic anterior cruciate ligament (ACL) reconstructions and 110 ACL reconstructions with our new technique, surgical complications related to the femoral interference screw fixation were evaluated. With our new technique, only one complication occurred while overall complications of 15.7% occurred in the ordinary group. Compared with the ordinary technique group, which had an average of 12.0 degrees screw divergence on anteroposterior radiographs and 13.5 degrees on lateral radiographs, our new technique had a significantly lower incidence of femoral screw divergence, with 8.0 degrees and 8.3 degrees on the anteroposterior and lateral views, respectively. This new technique could reduce a significant portion of complications that occur during endoscopic (single incision) bone-patellar tendon-bone ACL reconstruction.

Arthroscopically assisted reconstruction of the anterior cruciate ligament: initial clinical experience and minimal 2-year follow-up comparing endoscopic transtibial and two-incision techniques

The purpose of this study was to determine the outcome of endoscopic Anterior Cruciate Ligament (ACL) reconstruction and assess whether this technique modification offers any significant advantages over arthroscopically assisted reconstruction. A consecutive series of 90 athletically-active patients (67 males, 23 females) who underwent reconstruction for ACL deficiency using a patellar tendon autograft was retrospectively reviewed. The study group consisted of two treatment subgroups: Group 1-EA (Endoscopic-Assisted technique using no lateral femoral condylar incision) consisted of 45 patients with a mean age of 25 years (range 15 to 43 and Group 2-AA (Arthroscopic-Assisted technique using both anterior and lateral femoral condylar incisions) consisted of 45 patients with a mean age of 25 years (range 16 to 37). The study groups were evaluated at specific postoperative intervals with a mean follow-up in Group 1-EA of 30 months (range 24-37) and in Group 2-AA, 41 months (range 24 to 77). Serial KT-1000 results averaged 2 mm in both groups with 75% of Group 1-EA and 78% in Group 2-AA patients noted to have < or = 3 mm side-to-side differences. No statistically significant differences were noted for complications including patellofemoral pain, arthrofibrosis, harvest site pathology, or painful hardware. At ultimate follow-up however, this study suggests that both methods may result in similar and reproducible satisfactory outcome.

Femoral interference screw placement through the tibial tunnel: a radiographic evaluation of interference screw divergence angles after endoscopic anterior cruciate ligament reconstruction

Fifty patients who underwent single-incision arthroscopically assisted anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone autograft were reviewed. All procedures were performed using a technique for placement of the femoral interference screw that reduced the divergence between the femoral interference screw and the femoral bone plug. This technique includes securing the femoral interference screw by placing the screw driver through the tibial tunnel, anterior to the tibial bone plug. Using this technique, 8% of our patients had significant femoral bone plug and interference screw divergence; however, no patients had a divergence angle of greater than 15 degrees in either the anteroposterior or lateral planes. None of our patients were noted to have divergence angles consistent with decreased pullout strength. We had no complications caused by screw driver placement, and we did not experience any graft injury. We believe that adequate femoral bone plug and interference screw alignment can be achieved by using this technique during single-incision endoscopic ACL reconstruction.

Autograft bone-patella tendon-bone plug comminution with loss of ligament fixation and stability

Two cases are described in which bone plug comminution caused a loss of femoral fixation after endoscopic bone-patellar tendon-bone, anterior cruciate ligament autograft reconstruction. Clinically there was loss of knee joint stability, and radiographically the bone graft had dislodged. One case was salvaged by graft inversion, with femoral interference screw and tibial traction suture fixation. The second case required graft replacement with a patella bone-quadriceps tendon autograft.

Interference screw divergence in endoscopic anterior cruciate ligament reconstruction

Interference screws are commonly used for graft fixation in bone-tendon-bone patellar tendon anterior cruciate ligament (ACL) reconstruction. The clinical significance of graft screw divergence has not been well studied. This report retrospectively reviews our initial experience in 73 consecutive endoscopic (single-incision) ACL reconstructions using interference screw fixation. Femoral divergence occurred more frequently in the lateral plane (29%) than the anteroposterior (AP) plane (15%). No early graft failures were noted clinically or by KT-1000 arthrometer testing. If properly tested at the time of operation, it does not appear that divergence of femoral screws < 30 degrees leads to early clinical failure in endoscopic ACL reconstruction. We propose that stresses on the graft-screw-tunnel construct will concentrate distally when placed in a divergent fashion, resulting in a wedge effect. No changes in early range of motion protocols or rehabilitation are recommended if screw divergence is noted and provided intraoperative stability is noted.

Comparison of "inside-out" and "outside-in" interference screw fixation for anterior cruciate ligament surgery in a bovine knee

Despite numerous advances in graft fixation with anterior cruciate ligament (ACL) reconstruction, few studies have compared the fixation strength of interference screws placed "outside-in" and from "inside-out" techniques. To compare techniques, a bovine model was designed to fail at the femoral tunnel bone-screw interface. Twenty-four fresh bovine knees were stripped of all soft tissues except the ACL. The native ACL was loaded the failure at a strain rate of 50 cm/min with the knee flexed 45 degrees. One standardized femoral tunnel was created on all specimens. A 3/32-inch guide pin was drilled into the center of the ACL femoral origin and overreamed with an 11-mm reamer from inside-out until the lateral cortex was reamed. Consistently sized patellar bone blocks were created (8 x 5 x 25 mm) with an 8-mm tendon width. The bone blocks were randomized to an "inside-out" (group 1) and "outside-in" (group 2) technique. Bone blocks were secured with a 7 x 25 interference screw. Specimens were mounted with the femoral tunnel and bone block aligned parallel to the tensile force and strained to failure at 50 cm/min. Failure of the native bovine ACL occurred at a mean of 2,304 N (SD +/- 472 N; n = 24). The mode of failure for group 1 was 9 of 13 at the bone-screw interface and 4 of 13 interligamentous failures. The mode of failure for group 2 was 7 of 11 at the bone-screw interface, 3 of 11 interligamentous, and 1 bone block failure. The mean load to failure for group 1 was 1,151 N (SD +/- 320 N, n = 13) including the four ligamentous failures and 1,143 N (SD +/- 306 N, n = 9) excluding the ligamentous failures. The mean load to failure for group 2 was 1,017 N (SD +/- 262 N, n = 11), including all specimens and 843 N (SD +/- 262 N, n = 7) excluding the interligamentous and bone block failure specimens. The "inside-out" technique averaged 100 N greater fixation strength than the "outside-in" technique. Statistical analysis using two-sample Student's t-test showed no statistically significant differences between group 1 and group 2. Both techniques demonstrate comparable maximum load to failure in a bovine model tested at 50 cm/min.

Endoscopic anterior cruciate ligament reconstruction: modified technique and radiographic review

The original technique for endoscopic anterior cruciate ligament reconstruction has several potential complications because of constraints imposed by working through the tibial tunnel: improper femoral tunnel placement, violation of the femoral tunnel posterior wall, femoral interference screw divergence, graft laceration during screw insertion, and distal tibial bone block protrusion. We performed 100 consecutive endoscopic anterior cruciate ligament reconstructions with bone-tendon-bone autograft using a modified technique that minimizes each of these problems through the use of an accessory medial parapatellar portal. Postoperative radiographic review showed femoral screw divergence in only 9% of cases (average angle, 6.9 degrees), all in the anteroposterior plane. The tibial tunnel was drilled at an average of 66 degrees to the plateau and averaged 52 mm in length. There was no graft damage during screw insertion or protrusion of the bone blocks. We conclude that this modified technique allows simplified, reproducible tunnel and interference screw placement.

The effect of Kurosaka screw divergence on the holding strength of bone-tendon-bone grafts

Fresh-frozen porcine knees were used to demonstrate the effects of diverging Kurosaka screw placement on linear load to failure in simulated anterior cruciate ligament reconstructions. Screws, placed anteromedially (rear-entry or tibial type) or intraarticularly (endoscopic femoral type) into each tibia, were directed at 0 degree, 15 degrees, or 30 degrees divergence angles relative to a guide wire. Grafts were axially loaded to failure to determine holding strength. Hierarchical analysis of variance was used to analyze differences between tibial side and endoscopic femoral type screw placement and the angles of divergence. Overall, the difference in pullout strength between rear-entry (or tibial side) and endoscopic femoral type fixation was shown to be statistically significant (P < 0.001). Anteromedially placed screws showed a statistically significant decrease in holding strength at 15 degrees and 30 degrees compared with 0 degree of divergence (P < 0.05). Intraarticular screw placement resulted in a statistically significant decrease in holding strength only at 30 degrees of divergence (P < 0.05). This study supports the importance of accurate screw placement within the tibia to ensure optimal interference fixation and suggests that endoscopic screw placement may offer significant added security when there are minor degrees of divergence.

Assessment of initial fixation of endoscopic interference femoral screws with divergent and parallel placement

Divergence of the interference screw placement used for femoral fixation during endoscopically assisted reconstruction of the anterior cruciate ligament has been described. This study is a biomechanical evaluation in 12 pairs of fresh intact bovine knees of femoral interference screws placed divergently and parallel relative to the bone block and its tunnel. One knee of each pair had the interference screw placed in a parallel fashion and the other knee had a 15 degrees divergence from the bone plug. Paired specimens were used to provide an optimal comparison of biomechanical data of the two different screw placements. No statistically significant differences were seen between the two groups when looking at ultimate load, deformation, and stiffness. Mode of failure was of more concern: in 4 of 12 divergent constructs, bone plug pullout occurred compared with only 1 of 12 in the parallel construct. The pullout strength remains high even with divergence of up to 15 degrees between the bone plug and femoral interference screws placed endoscopically.

A comparison of clinical and radiological parameters with two arthroscopic techniques for anterior cruciate ligament reconstruction

We performed a comparative study of two series of 25 patellar tendon arthroscopic reconstructions of isolated chronic anterior cruciate ligament injuries, alternating between a double-incision (using a rear-entry guide) or single-incision technique (using a transtibial approach). The patients were reviewed to assess the clinical, KT-2000 and radiological differences at an average follow-up of 14 months (range 8-18 months). For the clinical evaluation the International Knee Documentation Committee Form was used. The following radiographic parameters were measured: (1) the direction of the femoral and tibial tunnels in the antero-posterior (AP) and lateral (LL) views; (2) the location of the anterior border of the intra-articular exit hole of the femoral tunnel in the LL radiologic view; (3) femoral interference screw divergence with the bone block. An extension loss < or = 5 degrees was detected in 40% of the double-incision and 36% of the single-incision patients (NS). A flexion loss < or = 10 degrees was present in 8% of the double-incision and 16% of single-incision group (NS). There were no differences in terms of pivot shift test between the two groups (pivot glide in 12% of both groups). The average side-to-side KT-2000 differences at the manual maximum test were 1.98 mm in the double-incision and 2.64 mm in the single-incision group. With the double-incision technique the femoral and tibial tunnels were divergent in the AP plane and crossed the joint at an angle of 37 degrees and 72 degrees, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)