Anterior cruciate ligament reconstruction with the endoscopic technique

The effect of anterior cruciate ligament graft rotation on knee biomechanics

PURPOSE

The purpose of this study was to evaluate the effects on knee biomechanics of rotating the distal end of the bone-patellar tendon graft 90° in anatomic single-bundle (SB) anterior cruciate ligament (ACL) reconstruction with a porcine model.

METHODS

Twenty (n = 20) porcine knees were evaluated using a robotic testing system. Two groups and three knee states were compared: (1) intact ACL, (2) deficient ACL and (3) anatomic SB ACL reconstruction with (a) non-rotated graft or (b) rotated graft (anatomic external fibre rotation). Anterior tibial translation (ATT), internal (IR) and external rotation (ER) and the in situ tissue force were measured under an 89-N anterior tibial (AT) load and 4-N m internal and external tibial torques.

RESULTS

A significant difference from the intact ACL was found in ATT at 60° and 90° of knee flexion for rotated and non-rotated graft reconstructions (p < 0.05). There was a significant difference in the in situ force from the intact ACL with AT loading for rotated and non-rotated graft reconstructions at 60° and 90° of knee flexion (p < 0.05). Under IR loading, the in situ force was significantly different from the intact ACL at 30° and 60° of knee flexion for rotated and non-rotated graft reconstructions (p < 0.05). There were no significant differences in ATT, IR, ER and the in situ force between rotated and non-rotated reconstructions.

CONCLUSION

Graft rotation can be used with anatomic SB ACL reconstruction and not have a deleterious effect on knee anterior and rotational biomechanics. This study has clinical relevance in regard to the use of graft rotation to better reproduce the native ACL fibre orientation in ACL reconstruction.

Endoscopic versus rear-entry ACL reconstruction: a systematic review

Anterior cruciate ligament reconstruction is commonly performed using the all-endoscopic (also known as all-inside or single-incision) method or the rear-entry (also known as outside-in or two-incision) method. We report a systematic review of four prospective, randomized clinical trials comparing these two operative techniques. Operative time was shorter in the all-endoscopic groups in two studies. A higher percentage of patients in the rear-entry group had a difference of 3 mm or less on the KT-2000 arthrometer, although the two surgical techniques were similar in the other studies. A higher rate of return to full activity was achieved in patients undergoing the rear-entry technique in one study. All four studies were similar in pain medication used, progression of rehabilitation, range of motion, quadriceps or hamstring strength, patellofemoral pain, one-leg hop test, Lysholm, Tegner, and International Knee Documentation Committee scores. Overall, these studies show similar outcomes comparing the all-endoscopic and rear-entry anterior cruciate ligament reconstruction techniques.

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.

Revision anterior cruciate ligament reconstruction: three- to nine-year follow-up

PURPOSE

With the increasing number of primary anterior cruciate ligament (ACL) reconstructions, revisions are more frequent. The literature quotes inferior results for revision cases when compared with primary ACL reconstruction. The purpose of the study was to review our institution's experience with revision ACL reconstruction.

TYPE OF STUDY

Retrospective case series.

METHODS

Thirty-five revision cases were performed between 1993 and 1999. Twenty-nine were available for follow-up. Subjective scores were calculated for Lysholm, Tegner, and International Knee Documentation Committee (IKDC) forms. Objective IKDC scores were determined. KT-1000 measurements were performed as well as isokinetic strength testing of quadriceps and hamstrings. Plain film radiographs were obtained to assess degenerative changes.

RESULTS

The average patient age at time of revision was 30.2 years, the average time to revision was 56 months, the follow-up from last revision was 67 months. Twenty-two patients had bone-patellar tendon-bone (BPTB) allograft, 6 had contralateral BPTB autograft, and 1 patient had Achilles allograft. Overall, KT-1000 measurement showed an average of 2.78 mm side-to-side difference of displacement. The allograft versus the autograft group was 3.21 mm versus 1.33 mm, respectively. Prerevision data were unavailable. However, all patients had a positive pivot-shift test before revision. Average postrevision Lysholm, Tegner, and subjective IKDC scores were 86.6, 11.86, and 85.86, respectively. Concerning the IKDC objective scores, 15 patients had an A score, 8 had a B score, and 4 had a C score. All 29 patients available for follow-up reported that they would have the surgery again. The average strength of quadriceps and hamstrings ranged from 82% to 88% of uninvolved side.

CONCLUSIONS

This study provides long-term follow-up with good results for revision ACL reconstruction. Attention to principles when performing revision ACL surgery is critical to provide satisfactory results.

LEVEL OF EVIDENCE

Level IV.

The effect of Workers' Compensation on clinical outcomes of arthroscopic-assisted autogenous patellar tendon anterior cruciate ligament reconstruction in an acute population

PURPOSE

To assess the effect of Workers' Compensation (WC) benefits on subjective outcomes of patients following anterior cruciate ligament (ACL) reconstruction.

TYPE OF STUDY

Prospective study of ACL reconstruction with bone-patellar tendon-bone in an acute population.

METHODS

From October 1991 through June 1997, 1,015 patients underwent ACL reconstruction, 769 with bone-patellar tendon-bone autografts; 235 met the criteria for this study. All chronic injuries, failed and/or bilateral reconstructions were excluded making the total population 139. The final populations included 115 patients in a non-WC group and 24 patients in a WC group. Average follow-up for was 34.5 months for the WC group and 33.6 months for the non-WC group. All patients had equal objective evaluations, which allowed the subjective criteria to be analyzed.

RESULTS

The results revealed a significant difference in the subjective data of patients with WC benefits. Uniformly, WC patients rated subjective criteria as far worse than the non-WC group in postoperative stages. The average of the 15-item visual analog scale showed statistically significant (P <.01) differences between the WC and non-WC groups. Average postoperative Tegner scores were 3.05 for the WC group and 6.02 for the non-WC group, which was statistically significant. The WC group did not return to their preinjury Tegner score.

CONCLUSIONS

The data show that the patients' perception of their knee function drastically differs from the objective findings on examination; therefore, it should be anticipated that the WC patient might have lower subjective outcomes from surgical treatment when compared with their non-WC counterparts.

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.

Consistent and accurate graft passage and interference screw guide wire placement during single incision anterior cruciate ligament reconstruction

Misplacement and misalignment of trocar pins and guide wires during single-incision anterior cruciate ligament reconstructions can lead potentially to a number of complications. These complications include unacceptable trocar pin exit locations, difficulty repositioning the trocar pin along the initial track after unsuccessful attempts at graft passage, as well as guide wire impingement and graft transection during interference screw advancement. To help overcome these complications, a surgical technique using an eccentric aimer and two-pin passer was developed to help provide precise and repeatable placement of both a trocar pin and guide wire.

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.

The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using a robotic testing system

Despite its current popularity and relative success, endoscopic reconstruction of the anterior cruciate ligament (ACL) using a bone-patellar tendon-bone (BPTB) graft has not yet been perfected. Using a recently developed robotic/UFS testing system, we assessed the overall stability of porcine knees following ACL reconstruction with different sites of tibial graft fixation--proximal, central, and distal. Testing of the intact knee was performed first to determine the normal anterior-posterior (A-P) displacements and in situ forces of the ACL under 110 N of anterior tibial loading of 30 degrees, 60 degrees, and 90 degrees of knee flexion. The knee was then reconstructed with a BPTB autograft, and the distal end of the graft was fixed sequentially at three different locations in each specimen--proximal, central, distal. A-P testing was repeated for each fixation site, and the resulting knee kinematics and the in situ forces of the grafts were compared to the intact case. The site of tibial fixation was demonstrated to have a significant effect on the resulting anterior displacement and internal rotation of the tibia as well as the in situ forces of the graft. Proximal fixation produced the most stable knee (A-P displacements reduced to 120% of intact at 30 degrees and 170% at 90 degrees), becoming significantly less stable with more distal fixation. These results suggest that proximal graft fixation may provide the most acute stability of the reconstructed knee.

Biomechanical consequences of replacement of the anterior cruciate ligament with a patellar ligament allograft. Part I: insertion of the graft and anterior-posterior testing

Nineteen fresh-frozen knee specimens from cadavera were tested for anterior-posterior laxity with 200 newtons of force applied to the tibia. A cylindrical cap of subchondral bone containing the tibial insertion of the anterior cruciate ligament was isolated with a coring cutter and was potted in acrylic. A thin wire was connected to the undersurface of the cap, and relative displacement between the cap and the tibia was measured with an isometer as the knee was extended. The cap of bone was connected to a load-cell that recorded force in the intact ligament during anterior-posterior testing with the tibia locked in neutral, internal rotation, and external rotation. The anterior cruciate ligament was then resected, and a femoral tunnel was drilled at the site where the isometer readings from the wire were the same as those obtained for the intact anterior cruciate ligament. A bone-patellar ligament-bone graft was used to reconstruct the anterior cruciate ligament, and the isometer measurements were repeated with the graft in place. The graft was pre-tensioned at 30 degrees of flexion to restore normal anterior-posterior laxity. Anterior-posterior laxity tests were repeated at this level of pre-tension (laxity-matched pre-tension) as well as at a level that was forty-five newtons greater (over-tension). The moment required to extend the knee was measured before and after insertion of the graft at both levels of pre-tension. When the tibia was locked in positions of internal and external rotation, the anterior-posterior laxities and the forces in the anterior cruciate ligament (generated by an anterior force applied to the tibia) were significantly less than the corresponding values with the tibia in neutral rotation at 20, 30, and 45 degrees of flexion (p < or = 0.05). Isometer readings for the intact anterior cruciate ligament indicated that the cap of bone retracted into the joint a mean and standard deviation of 3.1 +/- 0.8 millimeters as the knee was extended from 30 degrees of flexion to full extension. For each specimen, the isometer measurements for the trial wire and for the graft were within 1.5 millimeters of those for the intact anterior cruciate ligament. At laxity-matched pre-tension (mean, 28.2 +/- 16.8 newtons), the mean anterior-posterior laxities of the reconstructed knees were within 1.0 millimeter of the corresponding means for the intact knees between 0 and 45 degrees of flexion. Over-tensioning of the graft by forty-five newtons decreased the anterior-posterior laxity a mean of 1.2 millimeters at 30 degrees of flexion. Over-tensioning of the graft did not change the moment required to bring the knee to full extension.

Revision anterior cruciate ligament surgery: experience from Miami

Failed anterior cruciate ligament reconstruction as defined by recurrent patholaxity is increasingly commonplace. This report presents the findings of 54 patients who had unsuccessful intraarticular anterior cruciate ligament reconstruction to correct persistent instability and who subsequently underwent revision anterior cruciate ligament surgery. Before revision, patients were evaluated by clinical examination, KT-1000 arthrometer, radiographs, Lysholm knee score, Tegner activity scale, and subjective questionnaire. The results were compared at a mean of 32 months following revision surgery. There was an average of 16 months from index procedure to the time of revision. Autogenous patellar tendon grafts were used in 61% of the cases with 30% of these harvested from the contralateral knee. Fresh frozen patellar tendon was used in 35% and autogenous hamstring tendons in 4%. Revision was successful in objectively improving stability in all patients with an average KT-000 of 2.8 mm. Autogenous tissue grafts provided greater objective stability when compared with allograft tissue with average KT-1000 of 2.2 and 3.3, respectively. Functionally, however, there was no significant difference in outcome between the 2 groups. Harvesting of the contralateral patellar tendon was found to have no adverse long term effect. Subjectively, the results were significantly worse depending on the degree of articular cartilage degeneration. Only 54% of patients returned to their preanterior cruciate ligament injury activity level. Competence in various anterior cruciate ligament reconstruction techniques will facilitate revision surgery especially in avoiding preexisting tunnels and hardware. Correct graft placement and addressing the secondary restraints are critical to successful revision surgery.

Anterior cruciate ligament surgery 1996. State of the art?

During the past 20 years, numerous basic science and clinical studies have improved the treatment of the anterior cruciate ligament deficient knee. As our understanding of the short term and long term morbidity caused by the torn anterior cruciate ligament has improved, and the morbidity of surgical reconstruction has decreased, the indications for anterior cruciate ligament reconstruction have widened. Anatomic placement of the anterior cruciate ligament graft has improved the outcome of surgery, although various techniques are used to achieve that goal. The patellar tendon autograft has been established as the gold standard graft choice, but several graft choices are available, and have given similar results in early followup. One of the major advances in anterior cruciate ligament reconstruction has been the acceptance of early range of motion and controlled endurance and strength training during the postoperative period.

The "N + 7 rule" for tibial tunnel placement in endoscopic anterior cruciate ligament reconstruction

Tibial tunnel placement during endoscopic anterior cruciate ligament (ACL) reconstruction has received increased emphasis in the recent literature. Appropriate tunnel length is a critical technical consideration. A tunnel that is too short results in graft extrusion, necessitating supplemental fixation techniques. A tunnel that is too long may make distal fixation and femoral tunnel placement difficult. A simple rule is proposed that allows for correct tunnel length and allows placement of the bone plug consistently within the tibial tunnel, allowing interference screw fixation.

Anterior cruciate ligament graft rotation. Reproduction of normal graft rotation

The purpose of this study was to determine normal rotation of the anterior cruciate ligament and to provide a technique for reproduction of this rotation. Ten fresh-frozen knees were dissected of all soft tissue except for the anterior cruciate ligament. Specimens were secured in a vise in 60 degrees of flexion. Each tibia was allowed to spin freely on the femur, and rotation was recorded. Anterior cruciate ligament reconstructions, using bone-patellar tendon-bone grafts, were then performed on all specimens using four graft rotations. Each specimen was then tested to assess how the graft twist affected tibial rotation. The average tibial rotation of the normal anterior cruciate ligaments was 55 degrees internally. Previous descriptions of anterior cruciate ligament reconstructions have advocated medial or internal rotation of the graft to reproduce normal anatomic rotation of the anterior cruciate ligament. Our cadaveric dissections have demonstrated that the anterior cruciate ligament normally produces internal rotation of the tibia in relation to the femur. Reproduction of this anatomic rotation is accomplished with 90 degrees of lateral rotation of the tibial plug toward the fibula.

Definitive landmarks for reproducible tibial tunnel placement in anterior cruciate ligament reconstruction

The purpose of this prospective study was to define constant anatomic intraarticular and extraarticular landmarks that can be used as definitive reference points to reproducibly create a tibial tunnel for anterior cruciate ligament (ACL) reconstruction that (1) results in an impingement-free graft in full extension without an intercondylar roofplasty; (2) positions the tibial tunnel's intraarticular orafice sagittally central in the original ACL insertion without visually guessing; (3) positions the tibial tunnel such that the sagittal tunnel-plateau angle is parallel with the sagittal intercondylar roof-plateau angle in full extension to minimize shear seen by the graft at the tibial tunnel inlet, and by doing so; (4) maximizes tunnel length to avoid patellar tendon graft-tunnel length mismatch allowing for endosteal interference screw fixation on both sides of the joint. Anatomic dissections in 50 knees showed the ACL sagittal central insertion point on the intercondylar floor averages 7 mm (range 7 to 8 mm) sagittally anterior to the anterior margin of the posterior cruciate ligament (PCL) with the knee flexed 90 degrees such that the PCL may be used as a reliable reference landmark for locating the ACL sagittal central insertion. This constant relationship was found to be independent of knee size. Extraarticularly, beginning the tibial tunnel sagittally 1 cm above the superior (sartorial) border of the pes anserinus insertion and coronally 1.5 cm posteromedial from the medial margin of the tibial tubercle along the superior surface of the pes, directed toward the sagittal central ACL insertion, led to a sagittal tunnel-plateau angle that averaged 68 degrees (range 64 degrees to 72 degrees) with a corresponding tunnel length that averaged 58 mm (range 50 to 65 mm) in 23 knees. This data correlated well with data obtained clinically in a series of 50 consecutive ACL reconstructions using intraarticular PCL and extraarticular pes anserine-medial tibial tubercle referenced tibial tunnels in which postoperative full extension lateral radiographs confirmed a sagittal tunnel-plateau angle parallel or near parallel with the intercondylar roof-plateau angle in all cases averaging 68 degrees +/- 3.8 degrees. Tibial tunnel length averaged 60 mm (range 52 to 66 mm) and in no case was there a patellar tendon autograft-tunnel length mismatch.

Anterior cruciate ligament patellar tendon reconstruction: it is probably better to leave the tendon defect open!

The purpose of our prospective study was to establish whether or not in anterior cruciate ligament (ACL) patellar tendon reconstruction the tendon defect has to be closed. In 50 consecutive ACL patellar tendon reconstructions, the tendon defect was randomly closed (group I) or left open (group II). The following data were recorded from all patients on the 4th and 14th days post operation: range of motion (ROM), pain at rest, pain and validity at isometric contraction, ability of bent leg raising (at 4th day) and straight leg raising (at 14th day). All the patients underwent ultrasonographic examination after 3 months and X-ray scanning at 6 months post operation. Forty patients underwent a CT-scan examination at 6 months. Thirty patients underwent isokinetic testing between 10 and 12 months post operation. Evaluating the immediate post operation data, no statistically significant differences emerged between the two groups. Ultrasonography showed in 68% of the knees of group I (defect closed) a thickened patellar tendon (PT), while in 60% of group II it was of normal thickness. No patients of either group developed patella infera by X-ray evaluation 6 months post operation. CT scans at 6 months showed that 100% of the knees of group I had a thickened PT in toto (nearly twice as thick as normal). Scar tissue was present not only in its central third but also in more than half of the cases in the medial and lateral third. In group II 75% of the patients had a normal thickness PT and 25% presented with only a minimal thickening. Scar tissue was distinguished only at its central third.(ABSTRACT TRUNCATED AT 250 WORDS)

Endoscopic anterior cruciate ligament reconstruction: a modified technique for graft passage

This article describes a simple technique for graft passage during endoscopic anterior cruciate ligament reconstruction. A 0.62 Kirschner wire is used to create a composite graft from either an Achilles tendon allograft or bone--patellar tendon--bone graft. This composite graft is then passed (linearly) from the tibial tunnel to the femoral tunnel without disturbing the soft tissue in the lateral thigh.

The arthroscopic "impingement test" during anterior cruciate ligament reconstruction

A primary goal of ACL reconstruction is to avoid graft impingement, which may lead to loss of motion and/or an increased incidence of instability. Although surgeons are cognizant of this potential problem, the intraoperative correction of graft impingement is technically demanding because the graft-notch relationship is obscured by the trochlea articulating with the tibial plateau during the final 10 degrees of extension. We present a simple impingement test that is performed before graft insertion and fixation to help avoid this potential pitfall.

Graft-tunnel mismatch in endoscopic anterior cruciate ligament reconstruction: a new technique of intraarticular measurement and modified graft harvesting

The purpose of this study was to determine the incidence of bitunnel interference fixation and accurate femoral insertion site targeting using a modified technique of endoscopic anterior cruciate ligament (ACL) reconstruction. Thirty-four consecutive central-third bone-patellar tendon-bone autograft modified endoscopic ACL reconstructions were prospectively studied. A new technique was used intraoperatively to directly measure (a) intraarticular (graft) distance (IAD) and (b) patellar tendon graft length, thereby allowing calculation of optimal tibial tunnel length for each case. Accuracy of guide pin placement through this tibial tunnel into the proposed femoral insertion site was assessed, as was the ability to achieve interference fixation in both tunnels (minimum of 20 mm bone interference fixation within the tibial tunnel). A new technique for patellar tendon-bone harvesting and proximal graft fixation to address graft mismatch is described. The average IAD from tibial origin to femoral ACL insertion measured 26.3 +/- 3.0 mm (range 21-33). The average patellar tendon length (LP) was 48.4 +/- 6.0 mm (range 40-63). The average calculated tibial tunnel length (TT) necessary to achieve bitunnel fixation (TT > or = LP + 20 - IAD) was 42.1 +/- 5.3 mm (range 36-57). Establishment of the calculated tibial tunnel length was achieved in 25 cases (74%) (no graft-tunnel mismatch). Graft-tunnel mismatch, in which the tibial tunnel could not be established to the length calculated necessary to accommodate a minimum of 20 mm of bone graft, occurred in nine cases (26%). Graft-tunnel mismatch occurred more frequently in patients whose patellar lengths were > or = 50 mm (p < 0.005), but was not found to correlate specifically to IAD. Recession of the graft up into the femoral tunnel allowed accommodation of the mismatched graft (bitunnel interference screw fixation) in these nine cases, averaging 22.0 +/- 2.98 mm (range 16-29 mm) of available distal bone block fixation. Tibial tunnel fixation of > or = 20 mm was achieved in 30 patients (88%), 18 mm in two, 17 mm in one, and 16 mm in one. Measurement error resulted in inadequate distal graft accommodation in four patients in whom error averaged 3 mm. Targeting of the femoral insertion site guide pin was achieved without requiring any knee manipulation for all cases. Patellar tendon graft protrusion through the tibial tunnel and potentially suboptimal graft fixation poses a frequent problem during endoscopic ACL reconstruction.(ABSTRACT TRUNCATED AT 400 WORDS)