Notchplasty is associated with decreased risk of anterior cruciate ligament graft revision.

PURPOSE: Despite influencing knee biomechanics and outcomes, the use of notchplasty at time of anterior cruciate ligament reconstruction (ACLR) has not been evaluated with regards to risk of secondary injury and revision. This study evaluates this association. METHODS: 42 patients (21.7-years, IQR = 19.0-27.5) that underwent primary then revision ACLR at a single institution were contrasted with a case matched control group of patients with grafts that did not fail. Patients were propensity score matched in a 1:2 ratio by age, gender, and date of index procedure. Post-hoc statistical correction was made for post-index procedure sports participation level. RESULTS: Notchplasty was performed in 2 of 42 cases that went on to revision, and in 31 of 84 cases in the control group (p < 0.001). This was associated with reduced rates of revision ACLR (OR = 0.085, 95%CI = 0.019-0.378). A significant difference was seen in the post-ACLR activity level between groups (p = 0.028), with post-hoc testing highlighting those returning to competitive sport to be more likely to require subsequent revision (OR = 9.647, 95%CI = 1.947-47.795). Notchplasty remained significantly associated with (reduced) risk of revision surgery, despite the observed variation in post-ACLR activity (p = 0.001). CONCLUSION: Individuals whose graft failed following ACLR were significantly less likely to have had notchplasty performed as part of their surgery than a control group who did not suffer graft reinjury. We propose that this may be due to decreased tensioning of the graft as the knee enters dynamic valgus, which may be of great relevance to athletes undergoing ACLR to enable return to sport.

Notchplasty alters knee biomechanics after anatomic ACL reconstruction.

PURPOSE: The aims of this study were (1) to study the biomechanics of single-bundle anatomic ACL reconstructed knees with and without notchplasty using a robotic testing system and (2) to determine if there would be a difference between performing a small or large notchplasty. METHODS: Fifteen fresh-frozen specimens were used in this study. The ACL reconstruction (ACL-R) was performed using an anatomic single-bundle technique with the 8 mm soft tissue graft fixed at 30° with suspensory fixation on the femoral side and a screw and washer on the tibial side. The notchplasty was then created with a burr. The following knee states were compared: (1) ACL-R, (2) ACL-R with a small (3 mm) notchplasty, and (3) ACL-R with a large (6 mm) notchplasty. Four loading conditions were applied: (1) an anterior drawer with an 89 N anterior tibial load, (2) simulated pivot-shift loading, (3) a 5 Nm internal rotational moment, and (4) a 5 Nm external rotational moment. RESULTS: Under anterior tibial loading, anterior tibial translation increased, and graft force decreased significantly after ACL-R + 3 mm notchplasty and ACLR + 6 mm notchplasty compared to ACL-R alone at FE, 15° and 30° of knee flexion. There were no changes in either anterior tibial translation or graft force under simulated pivot-shift loading, internal rotational moment, or external rotational moment. CONCLUSION: When added to anatomic ACL reconstruction, notchplasty increased anterior tibial translation and decreased graft forces during low knee flexion angles. There was no difference between a small and large notchplasty. The findings of this study are clinically relevant as the purpose of anatomic ACL reconstruction is to restore normal knee laxity, and while notchplasty may be helpful in avoiding graft impingement and improving visualization, removing even 3 mm of bone leads to biomechanical changes.

Impingement following anterior cruciate ligament reconstruction: comparing the direct versus indirect femoral tunnel position.

PURPOSE: During anterior cruciate ligament (ACL) reconstruction, authors have suggested inserting the femoral tunnel at the biomechanically relevant direct fibres, but this higher position can cause more impingement. Therefore, we aimed to assess ACL graft impingement at the femoral notch for ACL reconstruction at both the direct and indirect tunnel positions. METHODS: A virtual model was created for twelve cadaveric knees with computed tomography scanning in which a virtual graft was placed at direct and indirect tunnel positions of the anteromedial bundle (AM), posterolateral bundle (PL) or centre of the both bundles (C). In these six tunnel positions, the volume (mm3) and mid-point location of impingement (°) were measured at different flexion angles. RESULTS: Generally, more impingement was seen with the indirect position compared with the direct position although this was only significant at 90° of flexion for the AM position (97 ± 28 vs. 76 ± 20 mm3, respectively; p = 0.046). The direct tunnel position impinged higher at the notch, whereas the indirect position impinged more towards the lateral wall, but this was only significant at 90° of flexion for the AM (24 ± 5° vs. 34 ± 4°, respectively; p < 0.001) and C position (34 ± 5° vs. 42 ± 5°, respectively; p = 0.003). CONCLUSION: In this cadaveric study, the direct tunnel position did not cause more impingement than the indirect tunnel position. Based on these results, graft impingement is not a limitation to reconstruct the femoral tunnel at the insertion of the biomechanically more relevant direct fibres.

Improvement of Posterior Cruciate Ligament Buckling and Anterior Tibial Subluxation by Anterior Scar Removal of the Posterior Cruciate Ligament: A Case Report.

Posterior cruciate ligament (PCL) buckling and anterior tibial subluxation are observed in patients with insufficient anterior cruciate ligament (ACL). Here, we report the case of a patient after ACL reconstruction in whom these symptoms were improved by anterior scar resection of buckled PCL. The patient was a 46-year-old man. Six years ago, he underwent ACL reconstruction; however, his condition was not satisfactory. Magnetic resonance imaging (MRI) showed intercondylar impingement of the graft, anterior tibial subluxation, and PCL buckling. Intercondylar notchplasty and resection of the anterior scar of PCL were performed arthroscopically. Postoperative MRI showed improvement in PCL buckling and anterior tibial subluxation. His symptoms improved, and he was able to jog one year after surgery.  Anterior scar resection of PCL may improve PCL buckling and anterior tibial subluxation after ACL reconstruction.

Quantifying graft impingement in anterior cruciate ligament reconstruction.

BACKGROUND: Anterior cruciate ligament reconstructions (ACLR) fail at a rate of 10-15%, with graft impingement often a cause. In this study we investigate the prevalence and causes of impingement seen during ACLR surgery. METHODS: We reviewed consecutive primary ACLR from 2012-2018. Graft impingement was estimated intraoperatively by placing the arthroscope through the tibial tunnel and passively extending the knee, observing how much was obscured by the lateral femoral condyle from an anterior and lateral direction. Preoperative MRI scans were used to measure the intercondylar notch; Notch Width Index (NWI) and Notch Depth Index (NDI). Positioning of the tunnels was determined on postoperative radiographs. RESULTS: There were 283 ACLRs performed with 33 failures diagnosed on MRI (11.7%). 257 patients had complete imaging and follow up (91%). The mean age was 28 (±9) years and mean follow-up 5.3 (±1.8) years. The mean NWI was 0.26(±0.03), and NDI was 0.49(±0.06). The tibial tunnel aperture was located 42(±6) % of the way from anterior-posterior and 39(±6) % from medial-lateral. Impingement requiring a notchplasty was observed in 80% of cases, with lateral impingement more prominent. CONCLUSIONS: The amount of impingement did not correlate with tunnel position, which was located within the recommended area. There was a weak negative correlation between NWI and lateral impingement (rs = -0.16, p = 0.01), and NDI and anterior impingement (rs = -0.12, p = 0.04), therefore a smaller notch is associated with greater impingement. Despite optimal tunnel positioning, impingement still occurs in a significant number of cases therefore notchplasty should always be considered to keep revision rates low.

Flexion contracture can be relieved by concurrent notchplasty in medial open wedge high tibial osteotomy.

BACKGROUND: Given that medial open wedge high tibial osteotomy (OWHTO) not only delays the progression of osteoarthritis but also alleviates the resulting pain, surgical outcomes would be improved if limited ROM can also be managed. In this regard, the effect of concurrent notchplasty on flexion contracture has not been evaluated. HYPOTHESIS: (1) Concurrent notchplasty in OWHTO would relieve flexion contracture regardless of the severity of osteoarthritis and this effect would be maintained over time, and (2) concurrent notchplasty would not cause any added complications compared to the same procedure without notchplasty. PATIENTS AND METHODS: In total, 107 patients who underwent OWHTO between 2011 and 2017 with a mean follow-up period of 46.6months (range: 24-102months) were reviewed. ROM was measured at three time points as follows: before surgery, at 6-12months postoperatively, and at the latest follow-up. The measurements were analyzed using a linear mixed model in terms of notchplasty and other factors, including age, sex, body mass index, preoperative hip-knee-ankle angle, lateral distal femoral angle, medial proximal tibial angle, correction angle, concurrent meniscectomy, postoperative posterior slope, and Kellgren-Lawrence grade. Then, ROMs at the three time points were compared between the notchplasty and non-notchplasty groups. RESULTS: Of the 107 patients, 47 underwent concurrent notchplasty. The linear mixed model regarding flexion contracture showed a significant notchplasty-by-time interaction (p<0.001). When comparing preoperative flexion contractures between the two groups, a significant difference was found (p<0.001). At 6-12months postoperatively, flexion contractures were relieved regardless of notchplasty; however, the difference between the groups was decreased (p=0.026). At the latest follow-up, flexion contractures were partly aggravated in both groups, but no significant difference was found between the groups (p=0.461). Comparison of flexion contracture between before surgery and at the latest follow-up in each group revealed a significant difference only in the notchplasty group (p<0.001, with notchplasty; p=0.197, without notchplasty). The linear mixed model regarding maximal flexion did not show any factor having a significant interaction with time. There were no surgical complications such as infection, thromboembolic events, and hemarthrosis, in both notchplasty and non-notchplasty groups. CONCLUSION: The preoperative difference in flexion contracture was overcome by adding notchplasty to OWHTO, and this improvement was maintained over time. No added complications were noted in the notchplasty group. The results should be interpreted with caution, considering measurement error of ROM. However, concurrent notchplasty in OWHTO deserves further study to validate its efficacy. LEVEL OF EVIDENCE: III, retrospective cohort study. IRB INFORMATION: Project No. S2020-0081, AMC IRB SOP.

Anterior cruciate ligament femoral-tunnel drilling through an anteromedial portal: 3-dimensional plane drilling angle affects tunnel length relative to notchplasty.

BACKGROUND: Notchplasty is a surgical technique often performed during anterior cruciate ligament reconstruction (ACLR) with widening of the intercondylar notch of the lateral distal femur to avoid graft impingement. The purpose of this study was to correlate femoral-tunnel length with 3-dimensional (3D) drilling angle through the anteromedial (AM) portal with and without notchplasty. MATERIALS AND METHODS: Computer data were collected from an anatomical study using 16 cadaveric knees. The anterior cruciate ligament (ACL) femoral insertion was dissected and outlined for gross anatomical observation. The dissected cadaveric knees were scanned by computed tomography (CT). Three-dimensional measurements were calculated using software (Geomagic, Inc., Research Triangle Park, NC, USA) and included the center of the ACL footprint and the size of the ACL femoral footprint. The femoral-tunnel aperture centers were measured in the anatomical posterior-to-anterior and proximal-to-distal directions using Bernard's quadrant method. The ACL tunnel was created 3-demensionally in the anatomical center of femoral foot print of ACL using software (SolidWorks®, Corp., Waltham, MA, USA). The 8-mm cylinder shaped ACL tunnel was rested upon the anatomical center of the ACL footprint and placed in three different positions: the coronal plane, the sagittal plane, and the axial plane. Finally, the effect of notchplasty on the femoral-tunnel length and center of the ACL footprint were measured. All the above-mentioned studies performed ACLR using the AM portal. RESULTS: The length of the femoral tunnels produced using the low coronal and high axial angles with 5-mm notchplasty became significantly shorter as the femoral starting position became more horizontal. The result was 30.38 ± 2.11 mm on average at 20° in the coronal plane/70° in the axial plane/45° in the sagittal plane and 31.26 ± 2.08 mm at 30° in the coronal plane/60° in the axial plane/45° in the sagittal plane, respectively, comparing the standard technique of 45° in the coronal/45° in the axial/45° in the sagittal plane of 32.98 ± 3.04 mm (P < 0.001). The tunnels made using the high coronal and low axial angles with notchplasty became longer than those made using the standard technique: 40.31 ± 3.36 mm at 60° in the coronal plane/30° in the axial plane/45° in the sagittal plane and 50.46 ± 3.13 mm at 75° in the coronal plane/15° in the axial plane/45° in the sagittal plane (P < 0.001). CONCLUSIONS: Our results show that excessive notchplasty causes the femoral tunnel to be located in the non-anatomical center of the ACL footprint and reduces the femoral-tunnel length. Therefore, care should be taken to avoid excessive notchplasty when performing this operation.

Does Bone Regrow After Notchplasty in ACL Reconstruction? A Prospective Computed Tomography Study With 2-Year Follow-up.

BACKGROUND: During notchplasty in anterior cruciate ligament (ACL) reconstruction, bone is excised from the lateral and roof area of the notch to widen the intercondylar space and avoid notch-graft impingement in extension. There are concerns that bone regrowth of the area will cause narrowing and increase the risk of complications. PURPOSE: To determine the possibility of late narrowing of the notch after notchplasty using computed tomography (CT) analysis. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Measurements were performed on CT scans (axial and sagittal planes with knee in extension) in patients who had undergone single-bundle anatomic ACL reconstruction using hamstring graft. Two axial image levels were used: at the anterior outlet and the anterior one-eighth level of the notch. The maximum notch height and width, the notch width at one-third and two-thirds of the preoperative notch midwidth height, the maximum condylar width, and the surface area of the lateral half of the notch were measured preoperatively and at 1 week and 2 years postoperatively. RESULTS: Included were 20 consecutive patients (mean ± standard deviation age, 28 ± 7.3 years; follow-up, 24.2 ± 3.3 months). At the anterior notch outlet, the maximum notch width increased by 1.9 ± 1.7 mm at 1 week postoperatively and narrowed by 0.3 ± 1.1 mm at the final follow-up, while the maximum notch height increased by 1.7 ± 1.9 mm and narrowed by 0.8 ± 1.8 mm, respectively. At one-eighth of the roof length, the maximum notch width increased by 1.1 ± 1.7 mm at 1 week postoperatively and narrowed by 0.1 ± 1.1 mm at the final follow-up, and the maximum notch height increased by 1.2 ± 1.5 mm and narrowed by 0.5 ± 1.5 mm, respectively. All differences were statistically significant when comparing the pre- to the immediate postoperative measurements, and they were nonsignificant when comparing the immediate postoperative to the final follow-up measurements. The same applied for the ratio of maximum notch width to maximum condylar width, indicating no postoperative narrowing of the notch. CONCLUSION: Notch size-shape after a 2-mm notchplasty did not change significantly in stable knees during the first 2 years after anatomic ACL reconstruction. Surgeons should consider performing this adjuvant technique when there is notch-graft impingement during surgery.

Clinical Outcomes of Arthroscopic Notchplasty and Partial Resection for Mucoid Degeneration of the Anterior Cruciate Ligament.

BACKGROUND: Mucoid degeneration of the anterior cruciate ligament (MD-ACL) is a chronic degenerative process involving a hypertrophied ACL, which may lead to notch impingement syndrome. As a treatment method, there is consensus regarding arthroscopic resection for MD-ACL resulting in good clinical outcomes; however, additional notchplasty remains controversial. The purpose of this study was to investigate clinical outcomes after arthroscopic partial resection of the ACL and additional notchplasty performed to minimize volume reduction of the ACL. STUDY DESIGN: Level IIIb retrospective cohort study. METHODS: Of 1810 individuals who underwent knee arthroscopic surgery performed by the same surgeon between July 2011 and October 2020, 52 were included, while 10 were excluded due to a follow-up period of <1 year. Clinical data including pain location, terminal flexion or extension pain, range of motion (ROM), Lysholm knee score, and Hospital for Special Surgery (HSS) knee score were assessed pre- and postoperatively. Additionally, according to the resected volume of the ACL, patients were classified into two groups: <25% (Group 1), and 25-50% (Group 2). Clinical outcomes were compared between the two groups. RESULTS: There were 17 (40.5%) men and 25 (59.5%) women with a mean age of 53.9 years (range, 16-81 years) at the time of surgery. The mean duration of symptoms before surgery was 14.4 months (range, 3-66 months). Arthroscopic partial resection of the MD-ACL was performed in all patients, and concomitant notchplasty was performed in 36 (81.8%). All clinical scores improved postoperatively, and were statistically significant (p < 0.01). However, there was no significant difference in clinical outcomes between groups 1 and 2 classified according to the resected ACL volume. Recurrence of MD-ACL was recorded in only one patient, 11 months after arthroscopic treatment. No patients underwent ACL reconstruction because of symptoms of anterior instability. CONCLUSION: Arthroscopic partial resection of the ACL and concomitant notchplasty yielded satisfactory outcomes for the treatment of MD-ACL. Notchplasty may be an alternative procedure to avoid total ACL resection and postoperative instability.

Effects of Notchplasty on Anterior Cruciate Ligament Reconstruction: A Systematic Review.

Purpose Notchplasty is a complementary surgical procedure often performed during anterior cruciate ligament reconstruction (ACLR) with the aim to widen the intercondylar notch and to avoid graft impingement. The aim of this review was to analyze the current literature evidence concerning the effects of notchplasty on clinical outcome after primary ACLR. Methods Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, and MEDLINE were used to search English language studies, from January 1990 to July 2015, concerning the effects of the notchplasty on ACLR, using the following keywords: "ACL" OR "anterior cruciate ligament" OR "ACL reconstruction" OR "anterior cruciate ligament reconstruction" AND "notch" OR "notchplasty" OR "intercondylar notch". Randomized and nonrandomized trials, case series, technical notes, biomechanical studies and radiological study were included. Results At the final screening 16 studies were included. Despite widely used, the usefulness of notchplasty during ACLR remains unclear. Some concerns emerged regarding potential harmful effects of notchplasty, mostly related to the knee biomechanics and postoperative blood loss. Notchplasty can be useful in the treatment of arthrofibrosis and in presence of bony spurs of the notch both in primary and revision surgery. However, the level of evidence of available literature is poor and there is a strong need for randomized controlled trials investigating the role of notchplasty on ACLR. Conclusion We suggest being aware of potential complications following notchplasty during ACLR before deciding to perform notchplasty in primary ACLR, reserving it for the surgical management of arthrofibrosis, treatment of notch osteophytosis and revision ACLR. Level of Evidence Level IV, systematic review of level II-IV studies.

The effects of graft size and insertion site location during anterior cruciate ligament reconstruction on intercondylar notch impingement.

BACKGROUND: Intercondylar notch impingement is detrimental to the anterior cruciate ligament (ACL). Notchplasty is a preventative remodeling procedure performed on the intercondylar notch during ACL reconstruction (ACLR). This study investigates how ACL graft geometry and both tibial and femoral insertion site location may affect ACL-intercondylar notch interactions post ACLR. A range of ACL graft sizes are reported during ACLR, from six millimeters to 11mm in diameter. Variability of three millimeters in ACL insertion site location is reported during ACLR. This study aims to determine the post-operative effects of minor variations in graft size and insertion location on intercondylar notch impingement. METHODS: Several 3D finite element knee joint models were constructed using three ACL graft sizes and polar arrays of tibial and femoral insertion locations. Each model was subjected to flexion, tibial external rotation, and valgus motion. Impingement force and contact area between the ACL and intercondylar notch compared well with experimental cadaver data from literature. RESULTS: A three millimeter anterior-lateral tibial insertion site shift of the maximum size ACL increased impingement force by 242.9%. A three millimeter anterior-proximal femoral insertion site shift of the maximum size ACL increased impingement by 346.2%. Simulated notchplasty of five millimeters eliminated all impingement for the simulation with the greatest impingement. For the kinematics applied, small differences in graft size and insertion site location led to large increases in impingement force and contact area. CONCLUSIONS: Minor surgical variations may increase ACL impingement. The results indicate that notchplasty reduces impingement during ACLR. Notchplasty may help to improve ACLR success rates.

Effect of Notchplasty in Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction.

BACKGROUND: The effects of notchplasty on the clinical outcome after anatomic double-bundle anterior cruciate ligament (ACL) reconstruction remain unclear. HYPOTHESIS: Anatomic ACL reconstruction with notchplasty would result in less risk of loss of extension and would provide adequate space for better graft healing, leading to better knee stability compared with anatomic ACL reconstruction without notchplasty. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 137 patients who underwent anatomic double-bundle ACL reconstruction were included. Seventy-three patients without notchplasty were classified as the control group, and 64 patients with 2-mm notchplasty were classified as the notchplasty group. The following evaluation methods were used: loss of extension, patient's subjective feeling of limited extension and pain at passive full extension, muscle strength, manual laxity tests, KT-1000 arthrometer measurement, patellofemoral joint findings, Tegner score, Lysholm score, subjective scores, and time to return to sports. Tearing of the reconstructed ACL and additional synovectomy were recorded. Both tibial and femoral tunnel positions were measured using 2-view radiographs: a Rosenberg and a lateral view. RESULTS: Loss of extension was larger in the notchplasty group compared with controls (at 6 months: 0.8° vs 1.4°, P = .012; at 2 years: 0.4° vs 0.9°, P = .0053). The number of patients with a feeling of limited extension was also larger in the notchplasty group (at 6 months: 13 patients graded 1+ [somewhat limited] and 2 patients graded 2+ [very limited] vs 18 graded 1+ and 6 graded 2+, P = .015; at 2 years: 2 graded 1+ and 0 graded 2+ vs 4 graded 1+ and 5 graded 2+, P = .011). Six patients in the notchplasty group required additional synovectomy because of the prolonged loss of extension, whereas no patient in the control group required additional synovectomy. There were no differences between groups regarding muscle strength, patellofemoral findings, Lysholm score, Tegner score, subjective scores, or time to return to sports. The KT-1000 arthrometer measurement was better in the notchplasty group (1.2 vs 0.4 mm, P = .0017). However, 6 patients in the notchplasty group showed an overconstrained knee (KT-1000 measurement ≤-2 mm), compared with only 1 patient in the control group. There were no differences between groups in the other manual laxity tests or the tunnel positions. CONCLUSION: In anatomic double-bundle ACL reconstruction, anterior stability was improved and there were no harmful effects on patellofemoral joint findings by 2-mm notchplasty; however, notchplasty likely caused overconstrained knee, leading to a need for additional synovectomy in some patients. In contrast, anatomic double-bundle ACL reconstruction without notchplasty did not increase the incidence of loss of extension or of graft failure.

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

PURPOSE: In an effort to minimize graft impingement among various ACL deficient states, we sought to quantitatively determine requirements for bone resection during notchplasty with respect to both volumetric amount and location. METHODS: A validated method was used to evaluate Magnetic Resonance Imaging scans. We measured the ATT of the medial and lateral compartments in the following four states: intact ACL (27 patients), acute ACL disruption; <2 months post-injury (76 patients), chronic ACL disruption; 12 months post-injury (42 patients) and failed ACL reconstruction (75 patients). Subsequently, 11 cadaveric knees underwent Computed Tomography (CT) scanning. Specialized software allowed virtual anterior translation of the tibia according to the average ATT measured on MRI. Impingement volume was analyzed by performing virtual ACLRs onto the various associated CT scans. Location was analyzed by overlaying an on-screen protractor. The center of the notch was defined as 0°. RESULTS: Average impingement volume changed significantly in the various groups compared to the intact ACL group (acute 577 ± 200 mm(3), chronic 615 ± 199 mm(3), failed ACLR 678 ± 210 mm(3), p=0.0001). The location of the required notchplasty of the distal femoral wall border did not change significantly. The proximal femoral border moved significantly towards the center of the notch (acute 8.6° ± 4.8°, chronic 7.8° ± 4.2° (p=0.013), failed ACLR 5.1° ± 5.9° (p=0.002)). CONCLUSION: Our data suggests that attention should be paid peri-operatively to the required volume and location of notchplasty among the various ACL deficient states to minimize graft impingement.

Arthroscopic management of mucoid degeneration of anterior cruciate ligament.

BACKGROUND: Mucoid degeneration of the anterior cruciate ligament (ACL) is a less understood entity. The purpose of this study was to diagnose mucoid degeneration of anterior cruciate ligament and to assess the effectiveness of arthroscopic treatment in these patients. MATERIALS AND METHODS: Between December 2007 and November 2011, 20 patients were diagnosed to be suffering from mucoid degeneration of anterior cruciate ligament (ACL) on the basis of magnetic resonance imaging (MRI), histopathology, and arthroscopy findings. 12 patients were males and 8 patients were females, with mean age of 42.2 years for males (range 28-52 years) and 39.4 years for females (range 30-54 years). They presented with pain on terminal extension (n=10) and on terminal flexion (n=2) without history of significant preceding trauma. MRI showed an increased signal in the substance of the ACL both in the T1- and T2-weighted images, with a mass-like configuration that was reported as a partial or complete tear of the ACL by the radiologist. At arthroscopy, the ACL was homogenous, bulbous, hypertrophied, and taut, occupying the entire intercondylar notch. A debulking of the ACL was performed by a judicious excision of the degenerated mucoid tissue, taking care to leave behind as much of the intact ACL as possible. Releasing it and performing a notchplasty treated impingement of the ACL to the roof and lateral wall. In one patient, we had to replace ACL due to insufficient tissue left behind to support the knee. RESULTS: Good to excellent pain relief on terminal flexion-extension was obtained in 19 of 20 knees. The extension deficit was normalized in all knees. Lachman and anterior drawer test showed a firm endpoint in all, and 85% (n=17) showed good to excellent subjective satisfaction. CONCLUSIONS: Mucoid hypertrophy of the ACL should be suspected in elderly persons presenting pain on terminal extension or flexion without preceding trauma, especially when there is no associated meniscal lesion or ligamentous insufficiency. They respond well to a judicious arthroscopic release of the ACL with notchplasty.