Anterior cruciate ligament bundle insertions vary between ACL-rupture and non-injured knees.

PURPOSE: The present study aimed to investigate the three-dimensional topographic anatomy of the anterior cruciate ligament (ACL) bundle attachment in both ACL-rupture and ACL-intact patients who suffered a noncontact knee injury and identify potential differences. METHODS: Magnetic resonance images of 90 ACL-rupture knees and 90 matched ACL-intact knees, who suffered a noncontact knee injury, were used to create 3D ACL insertion models. RESULTS: In the ACL-rupture knees, the femoral origin of the anteromedial (AM) bundle was 24.5 ± 9.0% posterior and 45.5 ± 10.5% proximal to the flexion-extension axis (FEA), whereas the posterolateral (PL) bundle origin was 35.5 ± 12.5% posterior and 22.4 ± 10.3% distal to the FEA. In ACL-rupture knees, the tibial insertion of the AM-bundle was 34.3 ± 4.6% of the tibial plateau depth and 50.7 ± 3.5% of the tibial plateau width, whereas the PL-bundle insertion was 47.5 ± 4.1% of the tibial plateau depth and 56.9 ± 3.4% of the tibial plateau width. In ACL-intact knees, the origin of the AM-bundle was 17.5 ± 9.1% posterior (p < 0.01) and 42.3 ± 10.5% proximal (n.s.) to the FEA, whereas the PL-bundle origin was 32.1 ± 11.1% posterior (n.s.) and 16.3 ± 9.4% distal (p < 0.01) to the FEA. In ACL-intact knees, the insertion of the AM-bundle was 34.4 ± 6.6% of the tibial plateau depth (n.s.) and 48.1 ± 4.6% of the tibial plateau width (n.s.), whereas the PL-bundle insertion was 42.7 ± 5.4% of the tibial plateau depth (p < 0.01) and 57.1 ± 4.8% of the tibial plateau width (n.s.). CONCLUSION: The current study revealed variations in the three-dimensional topographic anatomy of the native ACL between ACL-rupture and ACL-intact knees, which might help surgeons who perform anatomical double-bundle reconstruction surgery. LEVEL OF EVIDENCE: III.

The correlation between the femoral anterior cruciate ligament footprint area and the morphology of the distal femur: three-dimensional CT evaluation in cadaveric knees.

BACKGROUNDS: "Anatomical" anterior cruciate ligament (ACL) reconstruction is defined as the functional restoration of the ACL to its native dimensions. It is essential to obtain more accurate predictors of ACL size before surgery. The purpose of this study was to investigate the correlation between the native femoral ACL footprint size and the morphology of the distal femur using three-dimensional CT (3D-CT). METHODS: Thirty non-paired Japanese human cadaver knees were used. All soft tissues around the knee were resected except the ACL. For the evaluation of femoral condyle morphology, trans-epicondylar length (TEL), notch outlet length, axial notch area, and notch width index were measured using 3D-CT. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the boundaries of the ACL insertion site were outlined on the femoral side. An accurate lateral view of the femoral condyle was photographed with a digital camera. The size of the femoral ACL footprint, length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were measured with ImageJ software. RESULTS: Notch height, lateral notch area, and TEL were significantly correlated with the femoral ACL footprint area. Both axial notch area and notch outlet length were significantly correlated with the femoral mid-substance insertion area. CONCLUSION: Morphological evaluation using 3D-CT preoperatively may be useful in predicting the femoral ACL footprint size.

Anatomic and non-anatomic anterior cruciate ligament posterolateral bundle augmentation affects graft function.

PURPOSE: The purpose of this study is to compare knee laxity and graft function (tissue force) between anatomic and non-anatomic posterolateral (PL) bundle augmentation. METHODS: Twelve (n = 12) fresh-frozen mature, unpaired porcine knees were tested using a robotic testing system. Four knee states were compared: (a) intact anterior cruciate ligament (ACL), (b) deficient PL and intermediate bundles, (c) anatomic PL augmentation, and (d) non-anatomic PL augmentation. Anterior tibial translation (ATT), internal rotation (IR) and external rotation (ER), and the in situ tissue force were measured under an 89.0-N anterior tibial load and 4.0-N m internal and external tibial torques. RESULTS: Both anatomic and non-anatomic PL augmentation restored the ER, IR, and ATT of the intact knee at all knee flexion angles (n.s.). Both anatomic and non-anatomic PL augmentation restored the in situ tissue force of the ACL during ER and IR loading and ATT loading at all knee flexion angles except at 60° of knee flexion, where the non-anatomic PL augmentation did not restore the in situ tissue force of the ACL during external rotation loading and the anatomic PL augmentation did not restore the in situ tissue force of the ACL during IR loading. Furthermore, there were no differences in ATT, IR, ER, and in situ tissue force under anterior tibial loading, IR and ER loading between the two reconstruction groups. CONCLUSION: There were no significant differences between anatomic and non-anatomic PL augmentation using the porcine knee model.

Double-bundle anterior cruciate ligament reconstruction is better than single-bundle reconstruction in terms of objective assessment but not in terms of subjective score.

PURPOSE: A comparison of clinical outcomes between double-bundle (DB) and single-bundle (SB) anterior cruciate ligament (ACL) reconstruction for patients with ACL injury. METHODS: Sixty patients were treated with either SB (n = 30) or DB (n = 30) ACL reconstruction between 2011 and 2012. The hamstring tendons were autografted with suspensory fixation on the femoral side, while a bio-absorbable interference screw was used for fixation on the tibial side. These patients were evaluated using Lysholm score, International Knee Documentation Committee (IKDC) forms (both objective and subjective), Lachman test, pivot shift test, and KT 1000 arthrometer. RESULTS: After a median follow-up duration of 35.5 months (ranging between 30 and 42 months), the frequency of patients who had high objective IKDC scores was significantly higher in the DB group than those in the SB group. In terms of DB, the Lachman test was normal in 26 patients (86.7%), nearly normal in three patients (10%), and abnormal in one patient (3.3%); comparatively, in terms of SB, the Lachman test was normal in 20 patients (66.7%), nearly normal in eight patients (26.7%) and abnormal in two patients (6.6%). The pivot shift test was negative in 29 patients (96.7%) and 21 patients (70%) for DB and SB, respectively. The average KT-1000 side-to-side difference was 1.0 mm for DB and 1.5 mm for SB. The subjective IKDC and Lysholm score showed non-significant differences between both techniques. CONCLUSION: Double-bundle ACL reconstruction was found to have a significant advantage in anterior and rotational stability as well as objective IKDC than that of SB reconstruction. However, subjective measurements showed no statistical differences between the techniques. LEVEL OF EVIDENCE: II.

Clinical outcomes and biomechanical analysis of posterolateral bundle augmentation in patients with partial anterior cruciate ligament tears.

PURPOSE: To examine the clinical and biomechanical results of posterolateral (PL) augmentation to reconstruct damaged PL bundle while preserving the less-damaged anteromedial bundle for partial anterior cruciate ligament (ACL) tears in comparison with double-bundle ACL reconstruction. METHODS: Sixteen patients who underwent PL augmentation for partial ACL tears (Group P) and 37 patients who underwent double-bundle ACL reconstructions for complete ACL tears were examined (Group D). Anterior tibial translation (ATT) was evaluated using the KT-1000 arthrometer. ATT during the Lachman test and acceleration of posterior tibial translation (APT) during the pivot shift test were evaluated using an electromagnetic measurement system (EMS). Clinical outcomes were evaluated using the Lysholm score. Second-look arthroscopy was performed 1 year after surgery. RESULTS: The mean postoperative Lysholm scores were 91.7 ± 12.2 and 94.6 ± 7.2 in Groups P and D, respectively, and there was no statistically significant difference between the two groups. The mean side-to-side difference of ATT on the KT-1000 was significantly improved in both Groups P and D. In the EMS analysis, the mean side-to-side difference of ATT and the mean APT were significantly improved in both Groups P and D. There was no significant difference in the second-look evaluation between the two groups. CONCLUSIONS: The clinical and biomechanical outcomes of PL augmentation were satisfactorily comparable to those of double-bundle ACL reconstruction. PL augmentation could be a useful treatment option for patients with partial ACL tears. LEVEL OF EVIDENCE: IV.

Radiographic positions of femoral ACL, AM and PL centres: accuracy of guidelines based on the lateral quadrant method.

PURPOSE: Femoral tunnel positioning is an important factor in anatomical ACL reconstructions. To improve accuracy, lateral radiographic support can be used to determine the correct tunnel location, applying the quadrant method. Piefer et al. (Arthroscopy 28:872-881, 2012) combined various outcomes of eight studies applying this method to one guideline. The studies included in that guideline used various insertion margins, imaging techniques and measurement methods to determine the position of the ACL centres. The question we addressed is whether condensing data from various methods into one guideline, results in a more accurate guideline than the results of one study. METHODS: The accuracy of the Piefer's guideline was determined and compared to a guideline developed by Luites et al. (2000). For both guidelines, we quantified the mean absolute differences in positions of the actual anatomical centres of the ACL, AM and PL measured on the lateral radiographs of twelve femora with the quadrant method and the positions according to the guidelines. RESULTS: The accuracy of Piefer's guidelines was 2.4 mm (ACL), 2.7 mm (AM) and 4.6 mm (PL), resulting in positions significantly different from the actual anatomical centres. Applying Luites' guidelines for ACL and PL resulted in positions not significantly different from the actual centres. The accuracies were 1.6 mm (ACL) and 2.2 mm (PL and AM), which were significantly different from Piefer for the PL centres, and therefore more accurate. CONCLUSIONS: Condensing the outcomes of multiple studies using various insertion margins, imaging techniques and measurement methods, results in inaccurate guidelines for femoral ACL tunnel positioning at the lateral view. CLINICAL RELEVANCE: An accurate femoral tunnel positioning for anatomical ACL reconstruction is a key issue. The results of this study demonstrate that averaging of various radiographic guidelines for anatomical femoral ACL tunnel placement in daily practice, can result in inaccurate tunnel positions. LEVEL OF EVIDENCE: Diagnostic study, Level 1.

Short term results of anterior cruciate ligament augmentation in professional and amateur athletes.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction is a widely accepted procedure; however, controversies exist about ACL augmentation. The purpose of this study was to assess the clinical outcomes of ACL augmentation in professional and amateur athletes with isolated single bundle ACL tears. MATERIALS AND METHODS: A consecutive series of professional and amateur athletes with partial ACL tears who underwent selective bundle reconstruction were analyzed. Stability was assessed with the Lachman test, anterior-drawer test, pivot-shift test and KT-1000 arthrometer. Functional assessment was performed using the subjective Lysholm questionnaire. RESULTS: Fifty-six patients were enrolled. The mean follow-up period was 19.3 months. All patients had posterolateral bundle (PLB) tears, and no anteromedial bundle (AMB) tears were found. The Lysholm score improved significantly from 78 (SD = 2.69) preoperatively to 96 (SD = 3.41) postoperatively (P value <0.0001). The pivot-shift test, Lachman test and anterior-drawer test results were negative in all cases postoperatively. Anterior tibial translation from neutral was 4.9 mm (SD = 2.7) preoperatively, and decreased significantly to 2.1 (SD = 0.6) postoperatively, measured with a KT-1000 arthrometer (P value <0.00001). CONCLUSION: In this study, we showed that ACL augmentation had good results in symptomatic professional and amateur athletes, and although further studies are needed to investigate long-term results, we recommend this surgery for all symptomatic athletic patients, especially those who would like to maintain an active lifestyle. Level of evidence IV.

Evaluation of the Angle Between the Long Axis of the Femoral Anterior Cruciate Ligament Footprint and Bony Morphology of the Knee: A Cadaveric Descriptive Study.

Purpose: There have been numerous studies of the anterior cruciate ligament (ACL) anatomy, but few have focused on the long axis angle of the femoral ACL footprint. This study investigated the angle between the long axis of the femoral ACL footprint and the bony morphology of the knee. Methods: This study is a cadaveric descriptive study. Thirty non-paired formalin-fixed knees of Japanese cadavers were used. Anteromedial (AM) and posterolateral (PL) bundles were identified according to the tension pattern differences during the complete range of motion of the knee. In the ACL femoral footprint, there is a fold between the mid-substance insertion site and fan-like extension fibers. After identifying AM and PL bundles of mid-substance fibers, the mid-substance and fan-like extension fibers were divided into those bundles and stained. We defined the line passing through the center of the AM and PL bundles as the long axis of the ACL. The center points of each of the four areas and the angle between the long axis of the ACL and the bony morphology of the knee were calculated using Image J software. Results: The mean angle between the axis of the femoral shaft and the long axis of the ACL mid-substance insertion was 28.8 ± 12.2 degrees. The mean angle between the Blumensaat line and the long axis of the mid-substance was 54.2 ± 13.5 degrees. Conclusion: The mean angle between the axis of the femoral shaft and the long axis of the femoral ACL footprint was approximately 29 degrees. There is a wide variation in the long axis of the femoral ACL footprint. To achieve better clinical results through a more anatomically accurate reconstruction, it can be beneficial to replicate the ACL femoral footprint along its native long axis.

Morphometry of Posterior Cruciate Ligament in Knee joint - A Cadaveric Study.

Objectives: Surgical repair of severely injured posterior cruciate ligament is mandatory. Therefore, the anatomical features of the PCL and its two bundles description help to define the appropriate size of the allograft for excellent results in reconstruction surgeries. Material and methods: Fifty knees were dissected from twenty-five fresh human cadavers (15 male and 10 female) of donors used for teaching purpose. The length and footprint area of PCL and patellar tendon length were measured, and determined the range of normality according to sex and height. Results: The average lengths of the PCL's Antero-medial (AM) and posterolateral (PL) bundle were 35. 52 ± 0.66 mm and 32.76 ± 0.64mm, respectively in male and 35.37 ± 0.07 & 32.58 ± 0.61mm in female. The femoral footprint of PCL was 133.10 ± 0.7 mm2 in male and 133.05 ± 0.7 mm2 in female observed, while the tibial footprint 132.21± 1.02 mm2 in male and 132.42 ± 0.8 mm2 in female was observed. Conclusion: The AM and PL bundle lengths were higher in males than females. There was a strong correlation between height and length of ligaments but no correlation with age.

Failure load of the femoral insertion site of the anterior cruciate ligament in a porcine model: comparison of different portions and knee flexion angles.

BACKGROUND: This study compared the failure load of the femoral insertion site of the anterior cruciate ligament between different portions and knee flexion angles. METHODS: In total, 87 fresh-frozen, porcine knees were used in this study. Three knees were used for histological evaluation; the remaining 84 knees were randomly divided into 4 groups: anterior anteromedial bundle, posterior anteromedial bundle, anterior posterolateral bundle, and posterior posterolateral bundle groups (n=21 per group). The anterior cruciate ligament femoral insertion site was divided into these four areas and excised, leaving a 3-mm square attachment in the center of each bundle. Tibia-anterior cruciate ligament-femur complexes were placed in a material testing machine at 30°, 120°, and 150° of knee flexion (n=7), and the failure load for each portion was measured under anterior tibial loading (0.33 mm/s). RESULTS: Histological study showed that the anterior cruciate ligament femoral insertion site consisted of direct and indirect insertions. Comparison of the failure load between the knee flexion angles revealed that all the failure loads decreased with knee flexion; significant decreases were observed in the failure load between 30 and 150° knee flexion in the posterior anteromedial bundle and posterior posterolateral bundle groups. Comparison of the failure load according to different portions revealed a significant difference between the anteromedial and posterolateral bundle groups at 150° of knee flexion, but no significant difference among the groups at 30° of flexion. CONCLUSIONS: Although the failure load of the posterior portion decreased significantly in the knee flexion position, it (mainly consisting of indirect insertion) plays a significant role against anterior tibial load in the knee extension position; this appears to be related to the characteristics of the insertion site. Reflecting the complex structure and function of the ACL, this study showed that the failure load of the femoral insertion site varies with differences in positions and knee flexion angles.

The underlying mechanism of partial anterior cruciate ligament injuries to the meniscus degeneration of knee joint in rabbit models.

BACKGROUND: The diagnosis, treatment, and efficacy evaluation of anterior cruciate ligament (ACL) partial rupture remains controversial. This research aims to investigate the underlying mechanism of partial ACL injuries to the meniscus degeneration in the rabbit knee. METHODS: Sixty New Zealand white rabbits were randomly divided into three groups including an experimental group, a sham group (n = 6), and a blank control group (n = 6). The experimental group is composed of an anteromedial bundle (AMB) rupture group (n = 24) and a posterolateral bundle (PLB) rupture group (n = 24). Rabbits in the experimental group were subjected to right hind limbs knee surgery to induce ACL part injury under the arthroscopy. Finally, eight rabbits including 6 in the model group and 2 in the control group were sampled randomly on the 2nd, 4th, and 8th weeks respectively. We observed the typical form of the meniscus through HE staining. Expressions of inflammatory factors including interleukin-1ß (IL-1ß) and IL-17 in the knee joint fluid were determined by means of an ELISA. Analysis of the mRNA expressions of matrix metalloproteinases-13(MMP-13) was performed to evaluate the inflammatory mediators in the pathogenesis of the meniscus. RESULTS: HE staining results showed that the surface was rough and the tissues were loose displaying collagen fibers of varying thickness. Both IL-1ß and IL-17 in the synovial fluid and the positive rate of MMP-13 in addition to MMP-13 mRNA showed a demonstrable increase treads from the 2nd to the 8th week. The significant difference was found (P < 0.05) compared to the control group. CONCLUSION: We conclude that the elevated levels of IL-1ß and IL-17, along with increased MMP13 expression, resulted in meniscus degradation in the rabbit knee joint model with partial ACL injury.

Do Sex-Specific Differences Exist in ACL Attachment Location? An MRI-Based 3-Dimensional Topographic Analysis.

BACKGROUND: Female sex is an independent risk factor for an anterior cruciate ligament (ACL) injury, as the incidence of an ACL rupture is 4- to 6-fold higher in female athletes compared with their male counterparts. The ACL attachment location as a potential risk factor for the increased ACL rupture rate in women has never been reported in the literature. PURPOSE/HYPOTHESIS: The purpose of the present study was to investigate the 3-dimensional topographic anatomy of the ACL bundle attachment in female and male patients, with and without an ACL rupture, and identify potential sex-related differences. We hypothesized that the ACL attachment location would be significantly different between men and women, in both the intact- and ruptured-ACL states. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Magnetic resonance images of the knee from 90 patients (55 men, 35 women) with a ruptured ACL and 90 matched controls (55 men, 35 women), who suffered a noncontact knee injury without ACL rupture, were used to create 3-dimensional models of the femur and tibia. The ACL bundles' origin and insertion were outlined on each model, and their location was measured using an anatomical coordinate system. A 2-way analysis of variance was used to compare the ACL attachment location between male and female patients, with and without an ACL rupture. RESULTS: No significant differences were found between female and male participants regarding ACL attachment location (femoral origin and tibial insertion). Patients with a ruptured ACL demonstrated a significantly different ACL origin compared with the participants with an intact ACL by an average difference of 8.9% more posterior (P < .05) and 4.0% more proximal (P < .05) in men and 13.0% more posterior (P < .05) and 5.5% more proximal (P < .05) to the flexion-extension axis of the knee in women. CONCLUSION: The ACL attachment location should not be considered a risk factor for the increased ACL rupture rates in female compared with male athletes. However, a more posterior and proximal location of the femoral ACL origin might be a predisposing factor to an ACL rupture regardless of sex.

Isolated Tear Of Posterolateral Bundle Of Anterior Cruciate Ligament.

Anterior cruciate ligament injuries are very commonly encountered during routine MRI reporting and various signs have been described for their identification. However, the diagnosis of isolated bundle tears is difficult using MRI, thus can be easily overlooked, especially isolated tear of posterolateral bundle. We present a case of a young male with "Gap" and "Footprint" signs on MRI knee joint, which are considered highly specific of posterolateral ACL bundle tear.

Partial tears of the anterior cruciate ligament.

Partial anterior cruciate ligament (ACL) tears were first described nearly fifty years ago but the optimal treatment for these injuries continues to be a subject of considerable debate. A question remains whether it is advantageous to preserve the ACL remnant and augment it with a graft, or to debride it and proceed with a standard ACL reconstruction unhindered by remnant fibers in the notch. Clinical outcomes of bundle preserving surgery are promising. An increasingly large body of scientific evidence suggests that augmenting the intact bundle is beneficial in terms of vascularity, proprioception and kinematics. With this knowledge, a number of surgeons have developed techniques to augment the intact bundle of the ACL in partial tears and to biologically enhance standard reconstruction techniques by preserving the ACL remnant. Correct tunnel placement is critical for achieving successful short and long-term outcomes after ACL reconstruction. However, published studies have several limitations including a limited number of patients and lack of control groups for direct comparison of outcomes. Concerns continue to exist with respect to an increased risk of impingement following augmentation, responsible of cyclops syndrome. The objective of this article was to outline the diagnostic approach, describe a reproducible and simple surgical procedure that allows correct femoral tunnel placement without the need for aggressive notch debridement and report the clinical outcome of partial ACL reconstruction.

Two Helpful MRI Signs for Evaluation of Posterolateral Bundle Tears of the Anterior Cruciate Ligament: A Pilot Study.

BACKGROUND: Diagnosis of partial anterior cruciate ligament (ACL) tears is difficult on magnetic resonance imaging (MRI), particularly the isolated tears of the posterolateral bundle. PURPOSE: To describe 2 MRI signs of partial ACL tear involving the posterolateral bundle on conventional knee MRI sequences, specifically, the "gap" and "footprint" signs. STUDY DESIGN: Case-control study. METHODS: We retrospectively reviewed the MRI appearance of the ACL in 11 patients with arthroscopically proven partial ACL tears isolated to the posterolateral bundle, as well as in 10 patients with arthroscopically proven intact ACLs, and evaluated for the presence of gap and/or footprint signs. RESULTS: There was high degree of sensitivity and specificity associated with the MRI findings of "gap" and "footprint" signs with arthroscopically proven isolated posterolateral bundle tears. CONCLUSION: Gap and footprint signs are suggestive of posterolateral bundle tear of the ACL, and the presence of 1 or both of these imaging findings should alert the radiologist to the possibility of a posterolateral bundle tear.

Femoral footprint variation of the posterolateral bundle of the anterior cruciate ligament and double-bundle reconstruction.

BACKGROUND: The study is aimed to observe the range of variation of the ACL PLB femoral footprint and investigate countermeasures for accurate femoral bone tunnel placement during double-bundle ACL reconstruction. METHODS: The femoral insertions of the anteromedial bundle (AMB) and PLB of the ACL were dissected in 30 male cadaveric knees. The ACL footprint on the lateral intercondylar wall (LIW) was observed, and the shape of the LIW, the resident ridge, the angle between the ACL long axis and femoral axis (AA), and the vertical distance from the center of the PLB to the lowest cartilage border of the LIW (PD) were measured. RESULTS: The area most populated by the ACL fibers was directly under the resident ridge. AA = 18.7°±15.25° with variation from -18° to 56°, and PD=7.02±1.47 mm with variation from 3.75 to 11.08 mm. Both discrete values were very large in both groups of data. There were two kinds of LIW: trapezoidal (8 knees) and triangular (21 knees). Both AA and PD values exhibited significant differences between the two types of LIWs (P=0.00). CONCLUSION: AA and PD vary among individuals. The insertions and centers of the PLB cannot be exactly anatomically determined with one size. For double-bundle ACL reconstruction, an individualized intraoperative footprint observation for fresh cases with footprint remnants, or resident ridge and anteromedial bundle-interval identification for old ACL tears, can be reasonable methods for posterolateral tunnel orientation. CLINICAL RELEVANCE: Clinical relevance is observe the range of variation of the PLB femoral footprint for clinical double-bundle ACL reconstruction.

Partial tears of anterior cruciate ligament: Results of single bundle augmentation.

BACKGROUND: Partial tears of the anterior cruciate ligament (ACL) are common and usually present with symptomatic instability. The remnant fibers are usually removed and a traditional ACL reconstruction is done. But with increased understanding of ACL double bundle anatomy, the remnant tissue preservation along with a single bundle augmentation of the torn bundle is also suggested. The purpose of this study was to evaluate the results of selective anatomic augmentation of symptomatic partial ACL tears. Our hypothesis is that this selective augmentation of partial ACL tears could restore knee stability and function. MATERIALS AND METHODS: Consecutive cases of 314 ACL reconstructions, 40 patients had intact ACL fibers in the location corresponding to the anteromedial (AM) or posterolateral (PL) bundle and were diagnosed as partial ACL tears perioperatively. All patients underwent selective augmentation of the torn bundle, while keeping the remaining fibers intact using autogenous hamstring graft. A total of 38 patients (28 males, 10 females) were available with a minimum of 3 years followup. 26 cases had AM bundle tears and 12 cases had PL bundle tears respectively. Patients were assessed with International Knee Documentation Committee (IKDC) 2000 Knee Evaluation Form, Lysholm score; instrumented knee testing was performed with the arthrometer (KT 2000). Statistical analysis was performed to compare the preoperative and postoperative objective evaluation. RESULTS: At 3 years followup, 31.6% patients were graded A, 65.8% were graded B and 2.6% was graded C at IKDC objective evaluation. Manual laxity tests, Lysholm's score, mean side to side instrumental laxity and Tegner activity score improved significantly. 76% patients returned to preinjury level of sports activity after augmentation. CONCLUSION: The results of anatomic single bundle augmentation in partial ACL tears are encouraging with excellent improvement in functional scores, side to side laxity and return to sports activity.