Anterior cruciate ligament mucoid degeneration: a review of the literature and management guidelines

Do the Clinical and Radiological Features of Knees with Mucoid Degeneration of the Anterior Cruciate Ligament Differ According to Knee Osteoarthritis Status?

Background

The etiology and pathology of mucoid degeneration of the anterior cruciate ligament (MD-ACL) remain poorly understood. MD-ACL may be associated with knee osteoarthritis (OA) or a mechanism other than OA. This study evaluated the radiological differences between knees with MD-ACL and those with a normal ACL and compared the clinical and radiological features of knees with MD-ACL according to the knee OA status.

Methods

This retrospective study compared the radiological features of the intercondylar notch width index (NWI) and posterior tibial slope (PTS) of 67 MD-ACL patients (MD group) and 67 age-, sex-, and OA grade-matched patients with a normal ACL (control group). During the subgroup analysis, MD-ACL patients were divided into the non-OA subgroup (n = 41) and OA subgroup (n = 26). The pain location and characteristics of the knee, PTS, and NWI were compared between these subgroups.

Results

Compared to the control group, the MD group had a lower NWI (0.26 ± 0.03 vs. 0.28 ± 0.01, p < 0.001) and a larger PTS (11.3° ± 3.0° vs. 9.2° ± 2.5°, p < 0.001). During the subgroup analysis, the most common pain locations were the posterior and medial aspects of the knee in the non-OA subgroup (43.9%) and OA subgroup (53.8%), respectively. Pain on terminal flexion was the most common pain characteristic in both subgroups (non-OA subgroup, 73.1%; OA subgroup, 53.8%). The PTS was not different between subgroups (11.7° ± 3.2° in the non-OA subgroup vs. 10.6° ± 2.7° in the OA subgroup; p = 0.159). However, the non-OA subgroup had a lower NWI than the OA subgroup (0.25 ± 0.03 vs. 0.28 ± 0.02, p = 0.001).

Conclusions

Patients with MD-ACL had a lower NWI and a larger PTS than patients with a normal ACL. Furthermore, the clinical and radiological features of MD-ACL differed according to the knee OA status. A narrow intercondylar notch may be more closely associated with the development of MD-ACL without OA.

Percutaneous image-guided treatment of mucoid degeneration of the ACL in advanced knee osteoarthritis-Preliminary observations

OBJECTIVES

To describe the percutaneous image-guided treatment of mucoid degeneration of the ACL causing deep knee pain on flexion in patients with advanced knee osteoarthritis.

METHODS

Five patients with mucoid degeneration of the ACL complicating knee osteoarthritis underwent percutaneous image-guided steroid bupivacaine ACL sleeve injections over a 3-year period.

RESULTS

There were four males and one female of mean age 54 (range 48-59 years). Each patient had Kellgren and Lawrence grade 4 medial compartment knee osteoarthritis with coexistent mucoid degeneration of the ACL sleeve. Each patient complained of deep knee pain on flexion as a dominant symptom. Each patient underwent image-guided (CT or ultrasound) steroid bupivacaine injection of the ACL sleeve resulting in symptom resolution and improved mobility for a mean duration of 8 months, (range 6-15 months.) CONCLUSION: Mucoid degeneration of the ACL should be sought in patients with osteoarthritis presenting with deep knee pain on flexion. Image-guided ACL sleeve injection in affected patients may result in symptom resolution and potential deferral of planned knee replacement surgery.

ADVANCES IN KNOWLEDGE

Emphasises Image guided percutaneous treatment of Mucoid degeneration of ACL in patients with knee osteoarthritis.

Nutrient vessel dysfunction can contribute to mucoid degeneration of the posterior cruciate ligament coexisting with lipoma arborescens: A case study

INTRODUCTION

With the rapid improvement of magnetic resonance imaging (MRI), mucoid degeneration (MD) of the anterior cruciate ligament (MD-ACL) has become an established disease entity and mechanical factors, such as increased posterior tibial tilt and intercondylar notch impingement, have been proposed. However, symptomatic MD of the posterior cruciate ligament (MD-PCL) remains an orphan disease without any established etiology.

PRESENTATION OF CASE

A man in his 60s exhibited restricted range of motion with knee pain. MRI revealed PCL enlargement with high-signal intensity and tram-track appearance on T2-weighted sagittal images and lipoma arborescens (LA) in the suprapatellar pouch. On gadolinium-enhanced MRI, the distal PCL was not contrasted. Arthroscopy revealed an almost normal expanded appearance with partial loss of the envelope synovium. Debulking operation was performed. Pathological findings revealed intravascular thrombus formation in early lesions of MD, and intraligamentous vascular degeneration and severity of MD were proportional.

DISCUSSION

ACL is susceptible to mechanical external forces from surrounding tissues because of its anatomical features that induce protease expression, resulting in MD-ACL with denatured large aggregating proteoglycans deposition. Conversely, occlusion of nutrient vessels within the ligament was observed in this case of MD-PCL. Coexisting LA likely provoked an inflammatory response with hypercoagulability, resulting in thromboembolism of the envelope synovial nutrient vessel.

CONCLUSION

MD-CL is a disease entity comprising multiple pathologies. Although symptomatic MD-ACL is mainly caused by mechanical factors with a relatively high morbidity rate, nutrient vessel dysfunction can contribute to symptomatic MD-PCL with coexisting LA in middle-aged adults with an extremely low morbidity rate.

Severe mucoid degeneration of the anterior cruciate ligament (ACL) treated with conservative arthroscopic debridement and platelet-rich plasma (PRP) injection

Mucoid degeneration of the anterior cruciate ligament (ACL) can be treated with arthroscopic debridement, however, instability can ensue. Here, we present a fit and active woman in her 60s with severe mucoid degeneration of the ACL who underwent conservative arthroscopic debridement and treatment with intraligamentous administration of platelet-rich plasma (PRP). After 1 month, the patient demonstrated significant improvements in range of motion and pain symptoms, with nil resultant laxity. The patient was able to return to all recreational sporting activities and professional duties. Quantitative MRI conducted 6 months postoperatively revealed improved fibre orientation and formation of new parallel fibres. Compared with the preoperative scan, the mean grey value demonstrated darker pixel intensity with a smaller standard deviation (SD), potentially indicating a more uniform and less variable formation of ligamentous tissue. Therefore, PRP did not cause harm and was associated with benefit in combination with arthroscopic debridement.

Reconstruction Considerations Following Complete Excision of Mucoid-Degenerated Anterior Cruciate Ligament: A Retrospective Study

INTRODUCTION

Mucoid degeneration (MD) of the anterior cruciate ligament (ACL) is an unusual cause of knee pain and restricted movement, predominantly affecting the middle-aged population. Arthroscopic partial or total debridement of the mucoid ACL is the surgical treatment of choice. However, little is discussed in the literature regarding subsequent knee instability and functional outcomes following complete ACL excision.

METHODS

A retrospective study was conducted on patients who underwent arthroscopic total ACL excision for mucoid ACL. Pre- and post-operatively, the Tegner-Lysholm score, the International Knee Documentation Committee (IKDC) Subjective Knee Form, and subjective functional instability were used to grade the clinical outcomes.

RESULTS

Ten out of the 13 patients who underwent complete ACL excision were available for evaluation. All patients presented with knee pain on deep flexion or extension with a painfully limited range of motion. Post-operatively, all patients were relieved of their original pain and dysfunction. The mean post-operative IKDC and Tegner-Lysholm scores were 74.96 and 83.6, respectively. All patients had a Lachman test positive, while only two had a grade 1 pivot shift test positive. Two patients had occasional functional instability only after strenuous exercises. None of the patients underwent subsequent ACL reconstruction.

CONCLUSION

All patients reported improved functional outcomes. Only two out of 10 reported occasional instability during strenuous activity. Therefore, complete debridement of mucoid ACL in sedentary patients is safe and efficacious. However, active young patients may experience instability and require ACL reconstruction if it hinders their daily activities.

Mucoid Degeneration of the Anterior Cruciate Ligament: Characteristics and Conservative Management

Clinical and radiographic characteristics of mucoid degeneration of the anterior cruciate ligament (MD-ACL) were poorly documented in previous literature. And the optimal management strategy for MD-ACL remains unclear. Here, we summarized the characteristics associated with MD-ACL, and evaluated the clinical outcome of conservative management to MD-ACL.A total of 18 knees in 18 patients diagnosed with MD-ACL were collected and reviewed retrospectively. Sixteen patients underwent conservative management and two patients underwent arthroscopic surgery. Baseline demographic, clinical data, and pathologic changes of knee in magnetic resonance imaging (MRI) were recorded. Clinical outcome was evaluated with Visual Analogue Scale (VAS) and Oxford Knee Score (OKS).The most common clinical characteristic in patients with MD-ACL was knee pain (18/18), and seconded by mobility limitation (38.9%, 7/18). All patients presented a typical celery stalk sign with increased signal and diffuse thickening volume in the ACL in MRI. Thirteen patients companied with meniscus tear (72.2%, 13/18), and nine complicated with cartilage injury (50.0%, 9/18). Sixteen patients who underwent conservative treatment were followed up for 21.8 months, and a positive clinical outcome was observed with VAS decreasing from 5.3 ± 2.3 to 1.5 ± 1.9 and OKS decreasing from 27.5 ± 12.7 to 17.9 ± 11.8 (p < 0.001). The post-OKS score was highly correlated with age, duration of disease, and meniscus tear (r = 0.844, 0.707, and 0.474, p < 0.05, respectively). And the post-VAS highly correlated with age (r = 0.693, p < 0.05). Two patients who underwent arthroscopic surgery were followed up for 24.5 months, and the pain and function of knee was improved.Knee pain and meniscus tear was the main characteristic of MD-ACL in clinical and radiographic exam. Conservative treatment could be an alternative management for treatment of MD-ACL with positive clinical outcome. Old age, long duration of disease and complications from meniscus tears were associated with inferior outcome of conservative treatment for MD-ACL. LEVEL OF EVIDENCE:  IV.

Intercondylar Notch Pathology

The intercondylar notch of the knee is a relatively small area. However, numerous rare pathologies can arise in this region. A majority of the existing literature has focused on the cruciate ligament injuries, yet there are several other entities that can cause knee pain from within the intercondylar notch. This review focuses on identifying the various diagnostic and treatment options for rare benign and malignant lesions including ganglion cyst formation, mucoid degeneration, benign proliferative conditions, and intra-articular tumors. These entities are most often diagnosed with advanced imaging studies and treated arthroscopically. While rare, these pathologies are important to identify in patients with ongoing vague knee pain.

The association between anterior cruciate ligament degeneration and incident knee osteoarthritis: Data from the osteoarthritis initiative

Background

Though anterior cruciate ligament (ACL) tear has been widely accepted as an important accelerator for knee osteoarthritis (KOA), the role of intrinsic ACL degeneration in developing KOA has not been fully investigated.

Purpose

To determine whether ACL degeneration, in the absence of ACL tear, is associated with incident KOA over 4 years.

Study design

Cohort study; Level of evidence, 2.

Methods

Participants' knees in this nested case-control study were selected from the Osteoarthritis Initiative (OAI) study, with Kellgren-Lawrence grading (Kellgren-Lawrence grading) of 0 or 1 ​at baseline (BL). Case knees which had incident KOA (KLG ≥2) over 4 years, were matched 1:1 with control knees by gender, age and radiographic status. ACL signal intensity alteration (0-3 scale) and volume were assessed as compositional feature and morphology of ACL degeneration, using knee MRI at P0 (time of onset of incident KOA), P-1 (1 year prior to P0) and baseline. Conditional logistic regression was applied to analyze the association between measures of ACL degeneration and incident KOA.

Results

337 case knees with incident KOA were matched to 337 control knees. Participants were mostly female (68.5%), with an average age of 59.9 years old. ACL signal intensity alterations at BL, P-1 and P0 were significantly associated with an increased odds of incident KOA respectively (all P for trend ≤0.001). In contrast, ACL volumes were not significantly associated with incident KOA at any time points.

Conclusions

ACL signal intensity alteration is associated with increased incident KOA over 4 years, whereas ACL volume is not.The translational potential of this article: This paper focused on ACL signal intensity alteration which could better reflect ACL degeneration rather than ACL tear during the progression of KOA and explored this topic in a nested case-control study. Utilizing MR images from KOA participants, we extracted the imaging features of ACL. In addition, we established a semi-quantitative score for ACL signal intensity alteration and found a significant correlation between it and KOA incidence. Our findings confirmed that the more severe the ACL signal intensity alteration, the stronger relationship with the occurrence of KOA. This suggests that more emphasis should be placed on ACL degeneration rather than ACL integrity in the future.

Mucoid Degeneration of the Anterior Cruciate Ligament: A Case Report

Mucoid degeneration (MD) is an uncommon pathological phenomenon that specifically affects the anterior cruciate ligament (ACL). This condition arises from the infiltration of yellowish material within the fibers of the ACL, contributing to the clinical presentation characterized by discomfort and limited mobility. MRI has proven to be the foremost diagnostic modality in effectively distinguishing MD of ACL from other potential pathologies. Preoperative recognition of this condition facilitates straightforward diagnosis, particularly via characteristic findings observed during knee arthroscopy. We present a case of MD of ACL, review prior studies about the condition, and outline its clinical features and symptoms, including those observed in our specific case.

An Unusual Cause of Posterior Knee Pain: Mucoid Degeneration of the Anterior Cruciate Ligament - Case Report

Mucoid degeneration of the anterior cruciate ligament (ACL) is an uncommon cause of pain in the posterior region of the knee, of unknown pathophysiology and underdiagnosed. The best treatment modality is still under discussion. Resection of the lesion with partial ACL debridement has shown good results without the occurrence of instability. The authors present a case of mucoid degeneration of the ACL treated with resection of the mucoid degeneration and partial debridement of the ACL by arthroscopy.

Mucoid degeneration of the anterior cruciate ligament corrected with autograft reconstruction

The anterior cruciate ligament (ACL) is the most frequently injured knee ligament, typically in non-contact athletic injuries in young adults. Mucoid degeneration of the ACL (ACL-MD) is an uncommon ACL pathology in which glycosaminoglycans deposition within the collagenous bundles leads to hypertrophy, loss of full knee flexion and knee pain without instability. ACL-MD usually presents in individuals over 40 years with sudden-onset knee pain after minimal trauma or as an incidental MRI finding. ACL-MD is rarely described in young adults. We present a case of ACL-MD in a previously healthy adult in his early 20s who presented with 3-month recalcitrant dull left knee pain and limited range of motion after 'stepping funny' with slight twisting. This case highlights the need to critically reflect on the anatomical structures when presented with musculoskeletal pathologies and to consider the unique presentation of musculoskeletal disease in atypical age groups.

A Ganglion Cyst in the Anterior Cruciate Ligament of a 13-Year-Old Boy

Intra-articular ganglion cysts of the knee are a rare occurrence in pediatric patients, particularly involving the anterior cruciate ligament (ACL). Only a handful of case reports have been documented in the medical literature, highlighting the rarity of this condition. Patients with intra-articular cysts often experience knee discomfort and mechanical symptoms like locking of the knee. We present the case of a 13-year-old boy who had a unilateral intra-articular ganglion cyst of the ACL in his left knee. To diagnose and treat the cyst, we conducted radiographs and MRIs, and arthroscopic drainage was performed, resulting in a successful cyst decompression. Our case report provides an overview of the pathogenesis, diagnostic methods, treatment options, and complications of treatment for intra-articular cysts of the ACL. It highlights the rarity of this condition in pediatric patients and underscores the importance of prompt diagnosis and appropriate management.

Ancillary findings in distinguishing between anterior cruciate ligament mucoid degeneration and sprain on MRI: a practical approach

BACKGROUND

Imaging findings of both anterior cruciate ligament (ACL) sprain and mucoid degeneration overlap in some cases, which may cause errors in magnetic resonance imaging (MRI) evaluation.

PURPOSE

To determine the ancillary findings on MRI in distinguishing between ACL sprain and mucoid degeneration, and also to obtain a diagnostic scheme.

MATERIAL AND METHODS

MRI scans of 77 patients with ACL mucoid degeneration and 77 cases with ACL sprain were retrospectively evaluated to compare with regard to parameters of age, sex, side, the status of posterior cruciate ligament - medial collateral ligament - lateral collateral ligament, bone marrow edema, intraosseous cyst, subchondral sclerosis, chondromalacia, meniscus tear, effusion, and osteochondral body. A decision tree algorithm was created to predict pathology in ACL, whether it was a sprain or mucoid degeneration.

RESULTS

The prevalence of female sex, femoral intraosseous cyst, tibial intraosseous cyst, subchondral sclerosis, femoral chondromalacia, tibial chondromalacia, medial meniscus tear, and lateral meniscus tear were significantly higher in the ACL mucoid degeneration group (P < 0.001, P = 0.016, P < 0.001, P = 0.003, P < 0.001, P < 0.001, P < 0.001, and P < 0.001, respectively). The probability of being mucoid degeneration increased 41.2 times (95% confidence interval [CI] = 5.296-321.132) in cases with tibial intraosseous cyst and increased 1.05 times (95% CI = 1.010-1.080) with each one-year increase in age (P < 0.001 and P = 0.011, respectively). The decision tree algorithm had an overall accuracy of 79.2%.

CONCLUSION

Ancillary findings are helpful in the diagnosis of suspicious cases for ACL mucoid degeneration and ACL sprain. The decision tree algorithm offers a practical and successful approach to this issue.

Clinical and radiological comparison between partial and complete resection of the anterior cruciate ligament in patients with mucoid degeneration of the anterior cruciate ligament: a controlled clinical trial

INTRODUCTION

The pathology of a mucoid degeneration of the anterior cruciate ligament (MDACL) has been mentioned in several publications but due to its rare incidence it is not a well-known pathology. Partial or complete resection of the ACL is the option of choice after failed non-surgical treatment. However, the success rate of both surgical techniques and the subsequent risk of an ACL instability is not known. The purpose of this study was to compare the clinical and radiological outcome between partial resection and complete resection of the ACL in patients with MDACL.

MATERIALS AND METHODS

Patients with MDACL verified by MRI and persistent knee pain were treated by partial (Group I) or complete resection (Group II) of the ACL and were included in a controlled clinical trial after unsuccessful conservative treatment for at least 6 months. Demographic, clinical and radiological data including the thickness of ACL, ACL/intercondylar ratio, patient's age at the time of surgery, the presenting symptoms, range of motion and ligament stability assessed by the ACL ligament score (Lachman test) were collected. In addition, Tegner activity score and Lysholm score were evaluated preoperatively and at final follow-up after a minimum of 12 months.

RESULTS

At final follow-up with a mean of 16.8 ± 8.8 months (range 12-41; Group I: 18.3 ± 9.7 vs. Group II: 15.3 ± 8.0; ns), all patients were pain free. Postoperatively, positive Lachman tests were noted in all patients (100%) in Group II (n = 5 patients with grade II and n = 5 patients with grade III). In Group I, 8 patients (80%) showed a negative Lachman test (grade I) and 2 patients (20%) a slightly elongated Lachman test with a firm stop (grade II). The mean knee flexion at follow-up examination was 132° ± 7° (range 120°-140°; Group I: 129° ± 9° vs. Group II: 135° ± 4°; ns). In pairwise comparison, flexion angle increased significantly in both groups (Group I: p = 0.0124 and Group II: p < 0.001). Pairwise comparison of thickness of the ACL and ACL/intercondylar ratio prior to and post-surgery in Group I showed non-significant differences.

CONCLUSION

Both arthroscopic debridement and complete resection of the ACL lead to improvement of clinical and radiological findings in isolated MDACL. However, complete resection of the ACL will result in higher instability. Therefore, partial resection might be the better treatment option, especially in young patients with MDACL.

Increased posterior slope and coronal inclination of the tibial joint line after opening wedge high tibial osteotomy may induce mucoid degeneration of the anterior cruciate ligament: A case report

A mucoid degeneration of the anterior cruciate ligament (ACL) is regarded as a degenerative change in the ligament, which is clinically presented with pain on full extension or flexion. Regarding morphological factors, it has been reported that an increased posterior tibial slope can be a cause of ACL degeneration secondary to the repetitive overload. The increase in the tibial slope is among the potential problems after medial opening wedge high tibial osteotomy (OWHTO). Especially, a large wedge opening in the correction of severe varus deformity may lead to non-physiologic bony geometry including an increased posterior tibial slope and medial tibial coronal inclination. We present a 69-year-old man had undergone OWHTO with a wedge correction angle of 12.4° for Kellegren-Lawrence grade 2, medial uni-compartmental osteoarthritis of the left knee. Evaluations of the postoperative radiographs revealed postoperative changes in radiological parameters with mechanical medial proximal tibial axis (mMPTA) from 81.3° to 94.3°, and posterior tibial slope (PTS) from 12.2° to 15.8°. Physical examination at 3 years after surgery revealed a knee extension of 0° and a limitation to knee flexion with maximum flexion of 110° and, and severe knee pain was elicited when the knee approached deep flexion. MRI revealed an increased signal intensity along the substance of the ACL and multiple cystic lesions indicative of a ganglion formation around the proximal ACL attachment site extending into the adjacent lateral femoral condyle. Microscopic examination of the resected tissues showed mucoid degeneration and mucous cysts indicative of ganglions formation within the ligament substance and the bone at the attachment site. The reported case illustrates the importance of being aware of this potential complication following OWHTO.

Radiologic findings associated with mucoid degeneration of the anterior cruciate ligament

INTRODUCTION

Mucoid degeneration (MD) of the anterior cruciate ligament (ACL) is a well-recognized pathology characterized by the degradation of collagen fibers and infiltration of a mucoid-like substance. This study is to determine the anatomical associated factors for MD-ACL using radiographic and magnetic resonance imaging (MRI).

MATERIALS AND METHODS

This was a retrospective study on patients who had undergone knee arthroscopy between 2011 and 2020. The patients with MD-ACL were defined and enrolled by the MRI and arthroscopy. Eventually, 52 patients in the MD-ACL group (group 1) and 52 patients in the control group (group 2) were enrolled, following sex and age matching. Radiologic evaluation included the assessment of Kellgren-Lawrence (K-L) grade, mechanical hip-knee-ankle (HKA) angle, posterior tibial slope (PTS) angle, and Insall-Salvati ratio. The notch width index and transverse notch angle were measured on MRI, and the grade of trochlear dysplasia was defined. Logistic regression analysis, receiver operating characteristic (ROC) curves, and area under curve (AUC) were performed.

RESULTS

The ROM was significantly decreased in group 1, whereas the PTS angle was significantly larger in group 1. Combined ganglion cysts of ACL were found in 42/52 patients (80.7%) in group 1. The risk of MD-ACL was associated with a steeper PTS angle, increased Insall-Salvati ratio, male sex, higher K-L grade, and decreased transverse notch angle and notch width index. The cutoff values in ROC analysis were found to be ≤ 28.27% for the notch width index (AUC, 0.849; p < 0.001), > 12.2° for the PTS angle (AUC, 0.765; p < 0.001), and ≤ 47.4° for the transverse notch angle (AUC, 0.711; p < 0.001), but not significant for Insall-salvati ratio.

CONCLUSION

A steeper PTS angle, decreased notch width index, and transverse notch angle are significantly associated with the presence of MD-ACL. These factors should be considered during diagnosis or when determining the treatment strategy for symptomatic MD-ACL patients.

LEVEL OF EVIDENCE

Level IIIb.

Role of debulking mucoid ACL in unicompartmental knee arthroplasty: a prospective multicentric study

BACKGROUND

Mucoid degeneration of the anterior cruciate ligament (ACL) has been shown to cause restricted terminal range of motion and rest pain. If present in a patient undergoing unicompartmental knee arthroplasty, it can deteriorate the final outcome. This study aims to compare functional and clinical outcomes of debulking the mucoid ACL in patients undergoing mobile-bearing unicompartmental knee arthroplasty (UKA).

METHODS

Patients with mucoid ACL undergoing mobile-bearing UKA at five different centres by five different arthroplasty surgeons were included. They were segregated into two groups matched for all demographic and pre-operative values: group A did not undergo debulking; group B underwent open debulking by a 15-number blade prior to UKA. Patient-related outcome measures, rest pain, clinical outcomes, and subjective patient satisfaction were recorded and compared at 2 years follow-up.

RESULTS

A total of 442 patients (226 patients underwent debulking, 216 patients did not undergo debulking) were included. Both groups showed overall improvement after surgery, however, patients who underwent debulking performed better at 2 years follow-up in terms of Knee Society functional score, International Knee Documentation Committee scores, range of motion, rest pain and overall patient satisfaction (p < 0.05) as compared with their counterparts.

CONCLUSIONS

Debulking of mucoid ACL in patients undergoing unicompartmental knee arthroplasty significantly reduces the rest pain and improves the final range of motion of the knee joint, subsequently improving the overall functional and clinical outcome of the patient and resulting in greater patient satisfaction.

Mucoid degeneration of the anterior cruciate ligament: can platelet-rich plasma combined with reductionplasty provide better results?

Introduction: Mucoid degeneration of the anterior cruciate ligament (ACL) is commonly treated with arthroscopic debridement of the ACL. But many studies have reported the weakening and laxity of ACL postoperatively and on follow-up. Platelet-rich plasma (PRP) is known to influence musculoskeletal healing through multiple growth factors. Methodology: Five patients who were diagnosed as a case of mucoid degeneration of the ACL based on MRI, over a period of 1 year (December 2018-2019), were included in the study. Autologous PRP, prepared by double spin protocol, was injected into the remaining ACL after partial debridement was done. Results: Visual analogue scale and Lysholm scores improved compared with preoperative scores, along with strength (anterior drawer test and Lachman test). Conclusion: PRP can be used to improve the healing and strength of a weakened ACL after partial debridement, but further research is needed to demonstrate its efficacy.

Symptomatic ACL mucoid degeneration in middle-age athletes

Background

Mucoid degeneration of the anterior cruciate ligament (ACL) is an uncommon non-traumatic cause of knee pain and motion restriction, typically seen in a middle-aged population. Primarily, the management consists of partial arthroscopic debridement and notchplasty, which has proven satisfactory clinical and functional outcomes.

Study objectives

This review aims to highlight key clinical, radiological and arthroscopic findings of mucoid ACL degeneration, and also to provide an approach to manage a symptomatic middle-aged athlete.

Rationale

Due to the paucity of literature on ACL mucoid degeneration, symptomatic presentation in a middle-aged athlete can be challenging to manage. Diffuse central pain, motion restriction in extension or flexion, absence of trauma, and an intact enlarged ACL on Magnetic resonance imaging (MRI) should raise suspicion for mucoid degeneration in middle-aged athletes. Specific radiological and arthroscopic findings can help to confirm the diagnosis. In this review article, we have also described a new clinical test to mimic the pain due to anterior impingement in the presence of an enlarged ACL.

Conclusion

In symptomatic middle-aged athletes, knowledge of characteristic findings can help in the timely diagnosis of mucoid degeneration of ACL. Treatment options include arthroscopic debridement, notchplasty, ACL augmentation, and ACL reconstruction. The presence of associated injuries can influence return-to-sports prognosis.

Management of mucoid degeneration of the anterior cruciate ligament: a systematic review

PURPOSE

The purpose of this study was to investigate the outcomes of management of mucoid degeneration of the anterior cruciate ligament (MDACL) by performing a systematic review of methods of treatment that have been reported.

METHODS

A systematic literature search in the databases MEDLINE, Embase, Google Scholar, Cochrane, ISI web of science and Scopus was performed through July 2020 by three independent reviewers. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and registered in the PROSPERO database (CRD42018087782). Quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria.

RESULTS

A total of nine studies were eligible for review. All nine studies assessed the outcome of arthroscopic debridement of MDACL. A total of 313 knees in 292 patients were included. The mean follow up ranged from 13 to 72 months. There was strong association between MDACL and chondral lesions (82%) and between MDACL and meniscal tears (69%). The rate of simultaneous meniscectomy ranged from 13 to 44%. Postoperative pain relief ranged from 53.8 to 95%. There was an improvement in postoperative range of motion and outcome scores (Lysholm and International Knee Documentation Committee scores and the Knee Injury and Osteoarthritis Outcome Score). Postoperative Lachman test was positive in 40% of patients, and 6% of patients had symptomatic instability. The mean MINORS score was 9.5 out of 16 (4-12).

CONCLUSIONS

Arthroscopic debridement of the anterior cruciate ligament (ACL) results in satisfactory pain relief and improvement in knee outcome scores. Postoperative ACL laxity is common after arthroscopic ACL debridement, however, symptomatic instability is not. The need for delayed ACL reconstruction should be discussed preoperatively, especially if complete resection of the ACL is to be performed.

LEVEL OF EVIDENCE

IV.

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.

Symptomatic Posterior Cruciate Ligament Ganglion Cyst in a Child with Hemophilia: A Case Report

CASE

We report the case of an active 8-year-old boy with a history of hemophilia and with a 1-year history of knee pain and limited range of motion. Magnetic resonance imaging of the knee demonstrated a ganglion cyst arising from the posterior cruciate ligament (PCL). Arthroscopic decompression of the cyst was performed, and he was asymptomatic at the 1-year follow-up.

CONCLUSION

This case demonstrates a rare finding of a pediatric PCL ganglion cyst. We suggest that clinicians should be aware of this as a cause of knee pain in the pediatric population and that arthroscopic management can be successful.

Association Between MRI-Based Tibial Slope Measurements and Mucoid Degeneration of the Anterior Cruciate Ligament: A Propensity Score-Matched Case-Control Study

Background

The cause of mucoid degeneration (MD) of the anterior cruciate ligament (ACL), which is commonly observed on magnetic resonance imaging (MRI) of patients with knee pain, has yet to be elucidated. Despite the limited evidence on the relationship between ACL lesions (injury and MD) and tibial morphologic features (ie, posterior tibial slope), the potential association between the presence of ACL MD and medial and lateral tibial slope (MTS and LTS) has not been well-established.

Purpose

To investigate whether MTS and LTS measurements are associated with the presence of ACL MD.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Consecutive knee MRI examinations of patients referred by an orthopaedic surgeon for potential internal joint derangements were identified within a 4-year period. The presence of ACL MD and the MTS/LTS values were assessed by independent expert observers in consensus in a blinded fashion. From 413 consecutive knee MRI scans, a sample of 80 knees, including 32 knees with ACL MD (cases) and 48 knees with normal ACL (controls), were selected using propensity score matching method for age, sex, body mass index, and presence of severe medial tibiofemoral compartment cartilage damage. The association between ACL MD and MTS/LTS was evaluated using conditional regression models.

Results

Knees with ACL MD had higher values of LTS (mean ± SD, 7.18° ± 3.58°) in comparison with control knees (5.32° ± 3.35°). Conditional regression analysis revealed a significant association between LTS measurements (not MTS) and ACL MD; every 1° increase in LTS was associated with a 17% (95% CI, 1%-35%) higher probability of having ACL MD.

Conclusion

Excessive LTS was associated with the presence of ACL MD, independent of participants' age, sex, BMI, and cartilage damage severity.

[Atraumatic instability of the anterior cruciate ligament caused by an intraligamentous cyst]

A 28-year-old man reported that he has a feeling of "giving away" in his knee while playing soccer. He has had no previous injury. At a physical examination, the results of Lachman's test and the pivot shift test were pathological. Magnetic resonance imaging revealed an intraligamentous cyst of the anterior cruciate ligament (ACL). During arthroscopy it became evident that the cyst had destroyed the ACL. After ACL reconstruction, physiological stability of the knee joint was achieved. Joint cysts are rare and frequently cause pain and a limited range of motion. An association between intraligamentous cysts and instabilities of the affected joint has not been described so far. Preventive resection of asymptomatic and incidentally found intraligamentous cysts should be discussed.

A Retrospective Comparison of ACL Tear and Mucoid Degeneration MRI Findings and an Emphasis on Evaluating of ACL, Blumensaat, and PCL Angles

Objective:

To determine MRI findings that can differentiate anterior cruciate ligament (ACL) tears from mucoid degeneration.

Material and Methods:

Thirty-seven patients with complete ACL tears and 43 with ACL mucoid degeneration were included in this study. Discontinuity, the abnormal signal intensity of the ACL on fat-saturated-PD weighted images, contusions, a deep lateral femoral notch, anterior tibial translation, uncovered posterior horn of the lateral meniscus, a celery stalk appearance, thickening, ganglion cysts, intraosseous cysts, the ACL, Blumensaat, and posterior cruciate ligament (PCL) angles were evaluated. Optimum threshold values, sensitivity, specificity, and 95% CIs for the angles were calculated to predict the tear.

Results:

The prevalence of the significant findings in a tear versus mucoid degeneration, respectively, was as follows: discontinuity (97% vs. 0%, p < 0.001), contusions (65% vs. 2%, p < 0.001), the deep lateral femoral notch (22% vs. 0%, p = 0.001), anterior tibial translation (70% vs. 14%, p < 0.001), uncovered the lateral meniscus (46% vs. 7%, p < 0.001), a celery stalk appearance (0% vs. 66%, p < 0.001), thickening (19% vs. 100%, p < 0.001), ganglion cysts (14% vs. 70%, p < 0.001), and intraosseous cysts (8% vs. 63%, p < 0.001). Threshold values of ACL, Blumensaat, and PCL angles to predict the tear were ≤36° (78% sensitivity, 91% specificity), >11° (84%, 81%), and ≤96° (65%, 91%), respectively.

Conclusion:

A celery stalk appearance in the mucoid degeneration and discontinuity in an ACL tear are important in the differential diagnosis. ACL, Blumensaat, and PCL angles can be helpful in settings of diagnostic uncertainty.

Anterior translation of the tibia in relation to femur in mucoid degeneration of ACL - An observational study

Background

Mucoid degeneration (MD) of the anterior cruciate ligament (ACL) are a well-known pathological entity.We have encountered several patients with MD of the ACL, found to have a anterior translation of tibia a exceeding 5 mm with an intact ACL. We studied this cohort and investigated the likely cause of this.

Methods

A retrospective search of our department's radiology system to identify all patients referred from the knee orthopaedic clinic for MR imaging over a span of 10 years. All patients had MD within the substance of the ACL and an intact ACL. We evaluated the degree of anterior translation of the tibia (ATT) in relation to the femur in mucoid degeneration of ACL.

Results

We identified 464 consecutive cases. The mean age was 52 years. There was a male predominance of 261 to 203 female. The average PTF measurement was 2.4 mm with a range of 0-20mm. Of the 464 cases, 3 397 patients had an insignificant ATT of < 5 mm. (0mm. 67. 67 67 patients had a ATT >5 mm. Of them, 32.8% had a ATT of 6 mm, 53.7% had a ATT range between 7 and 9 mm, with the remaining 13.4% above 9 mm in length.

Conclusion

It is essential to look for other secondary signs of ACL tears and not only focus on ATT as well as correlate this with clinical findings.

Increased Posterior Tibial Slope After Medial Open-Wedge High Tibial Osteotomy May Result in Degenerative Changes in Anterior Cruciate Ligament

BACKGROUND

This study aimed at evaluating changes in posterior tibial slope angle (PTSA) and the anterior cruciate ligament (ACL) before and after medial open-wedge high tibial osteotomy (MOWHTO) through 2-staged arthroscopic findings and verified whether the ACLs would be affected by the changed PTSA. We also evaluated which predisposing factors could influence ACL changes after MOWHTO.

METHODS

From July 2010 to March 2016, 164 knees that could follow the second-look arthroscopy at the time of plate removal were enrolled. Radiologically, preoperative and postoperative hip-knee-ankle angle, femorotibial angle, medial proximal tibial angle, and PTSA were evaluated. Based on our previous study, we assessed the ACL using the macroscopic grading system (normal, abnormal degenerative, and partially ruptured ACL) by first- and second-look arthroscopy and compared it before and after HTO. The correlation between changes in PTSA (△PTSA) and ACL was evaluated. We also assessed predisposing factors that might affect ACL changes.

RESULTS

Mean age at the time of osteotomy was 57.2 ± 5.1 years and time interval between the 2-stage arthroscopies was 26.3 ± 4.0 months. PTSA significantly increased after MOWHTO (P < .001). ACL stage at second-look arthroscopy was significantly progressed compared to first-look findings (P < .001). △PTSA was larger in the progressed group (2.1°; P < .001). Multivariate logistic regression indicated that greater body mass index (odds ratio, 1.2; P = .029) and larger △PTSA (odds ratio, 1.3; P = .008) were predisposing factors.

CONCLUSION

Increased posterior tibial slope following MOWHTO may result in degenerative ACL changes. Greater body mass index and larger △PTSA were predisposing factors for ACL degeneration after MOWHTO.

Intraarticular Ligament Degeneration Is Interrelated with Cartilage and Bone Destruction in Osteoarthritis

Osteoarthritis (OA) induces inflammation and degeneration of all joint components including cartilage, joint capsule, bone and bone marrow, and ligaments. Particularly intraarticular ligaments, which connect the articulating bones such as the anterior cruciate ligament (ACL) and meniscotibial ligaments, fixing the fibrocartilaginous menisci to the tibial bone, are prone to the inflamed joint milieu in OA. However, the pathogenesis of ligament degeneration on the cellular level, most likely triggered by OA associated inflammation, remains poorly understood. Hence, this review sheds light into the intimate interrelation between ligament degeneration, synovitis, joint cartilage degradation, and dysbalanced subchondral bone remodeling. Various features of ligament degeneration accompanying joint cartilage degradation have been reported including chondroid metaplasia, cyst formation, heterotopic ossification, and mucoid and fatty degenerations. The entheses of ligaments, fixing ligaments to the subchondral bone, possibly influence the localization of subchondral bone lesions. The transforming growth factor (TGF)β/bone morphogenetic (BMP) pathway could present a link between degeneration of the osteochondral unit and ligaments with misrouted stem cell differentiation as one likely reason for ligament degeneration, but less studied pathways such as complement activation could also contribute to inflammation. Facilitation of OA progression by changed biomechanics of degenerated ligaments should be addressed in more detail in the future.

Feasibility of T1rho and T2 map magnetic resonance imaging for evaluating graft maturation after anatomic double-bundle anterior cruciate ligament reconstruction

Background

Although T1rho and T2 map magnetic resonance imaging (MRI) have been perceived as useful diagnostic modalities for cartilage degeneration, no studies have assessed whether these two sequences are useful for monitoring ACL graft maturation after ACL reconstruction. The present study examined whether the two sequences reflect graft function and maturation after ACL reconstruction.

Methods

Twenty consecutive patients who consented to undergo MRI at 3, 6, and 12 months after double-bundle ACL reconstruction were enrolled. MRI was performed using T1 rho and T2 map sequences in a single session. Temporal changes in T1rho and T2 values of a purely tendinous portion of graft were assessed at each time point. Correlations were analyzed between T1rho or T2 map values and clinical results, including anteroposterior laxity at 2 and 4 years postoperatively, pivot shift test results at 4 years, and graft tension on second-look arthroscopy. Separate analyses were performed for the anteromedial bundle (AMB) and posterolateral bundle (PLB).

Results

T1rho sequence was able to visualize the tendinous portions of AMB and PLB more clearly than T2 map sequence even on gray-scale images. Mean T1rho and T2 map values gradually decreased during the first operative year, but the trend was more prominent and consistent for T1rho values than for T2 map values. Correlation analysis revealed that T1rho and T2 map values at 1 year correlated significantly with anteroposterior laxity at 2 and 4 years. This trend was found in both AMB and PLB. Both T1rho and T2 map values failed to exhibit a statistical correlation with arthroscopic findings of graft tension.

Conclusions

The present study was the first trial to assess the feasibility of T1rho and T2 map sequences to objectively monitor the course of graft maturation after ACL reconstruction. Both sequences successfully detected purely tendinous portions of graft, and mean values gradually decreased during the first year postoperatively. Both values at 1 year correlated significantly with anteroposterior laxity of the knee joint at 4 years, indicating that the values reflected graft fate.

Does the pre-operative status of the anterior cruciate ligament affect the outcomes following medial open-wedge high tibial osteotomy?

BACKGROUND

This study aimed to assess the morphological degeneration of the anterior cruciate ligament (ACL) through magnetic resonance imaging (MRI) and arthroscopy. It analyzed whether the pre-operative ACL status would affect the radiologic and clinical outcomes following medial open-wedge high tibial osteotomy (MOWHTO).

METHODS

A total of 150 knees were enrolled that underwent MOWHTO concomitant arthroscopic debridement for the treatment of varus osteoarthritis. Mean age was 56.1 ± 5.0 years and mean follow-up was 61.2 ± 21.4 months. The ACLs were staged based on MRI and arthroscopy. To exclude the influence of demographic factors on outcomes, the between-group differences were assessed. Radiologic evaluation included hip-knee-ankle angle, femorotibial angle, medial proximal tibial angle, posterior tibial slope angle, and Kellgren-Lawrence grade. Clinical evaluation included American Knee Society Score (AKSS) and knee joint range of motion (ROM).

RESULTS

The ACLs were classified into intact (75 knees, 50.0%), mucoid degeneration (59, 39.3%), chronic partial tear (10, 6.7%), and complete tear (six, 4.0%) according to MRI. They were also classified into four stages: normal (95 knees, 63.3%), abnormal (36, 24.0%), partial tear (13, 8.7%), and complete tear (six, 4.0%) according to arthroscopic appearance. There were no significant between-group differences in each variable. Changes in Kellgren-Lawrence grade did not show significant between-group differences. No significant between-group differences were observed in AKSS and ROM.

CONCLUSIONS

The pre-operative status of ACL did not influence the outcomes following MOWHTO at midterm follow-up.

LEVEL OF EVIDENCE

Level IV, case series.

Outcome of Arthroscopic Treatment of Mucoid Degeneration of the Anterior Cruciate Ligament

Background

Mucoid degeneration of the anterior cruciate ligament is a rare pathological entity. Several authors have identified this condition, described their experiences, and suggested their own guidelines for management. The aim of this study was to detail the clinical, radiological, arthroscopic, and pathological findings of mucoid degeneration of the anterior cruciate ligament and report the clinical outcomes following arthroscopic treatment.

Methods

A historical cohort of patients who underwent arthroscopic total or partial excision of the anterior cruciate ligament due to mucoid degeneration between 2011 and 2014 were reviewed. The minimum follow-up was 3 years. Demographic, radiological, and histological findings, type of surgery, and clinical pre- and postoperative data were analyzed. The visual analogue scale score, the International Knee Documentation Committee score, and the Tegner Lysholm Knee Score were collected preoperatively, postoperatively, and during the follow-up period.

Results

Seventeen females (67%) and eight males (33%) were included in the final analysis. The mean age at the time of surgery was 57 years (range, 31 to 78 years). Partial resection of the anterior cruciate ligament was done in seven cases and a complete resection in 18 cases. No reconstruction was performed at the same time. A positive Lachman test and a negative pivot shift were noted after surgery in all cases. Anterior cruciate ligament reconstruction was required in only one young patient due to disabling instability. At last follow-up, the mean visual analogue scale score, International Knee Documentation Committee score, and Tegner Lysholm Knee score improved (p < 0.01).

Conclusions

Our study provides further evidence that arthroscopic total or partial excision of anterior cruciate ligament is a safe and effective treatment for mucoid degeneration of the anterior cruciate ligament, improving patient satisfaction and function without causing clinical instability in daily activities. However, young patients should be forewarned about the risk of instability, and an anterior cruciate ligament reconstruction could be necessary.

Mucoid degeneration of the cruciate ligaments in osteoarthritis under primary total knee arthroplasty

Mucoid degeneration of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) with osteoarthritis is rarely reported. We experienced two knee osteoarthritic patients who had symptomatic mucoid degeneration of their ACL, and their PCL was also diagnosed as mucoid degeneration in histological evaluation. Preoperative radiological evaluation could not reveal precisely whether the degeneration had extended to the PCL. We obtained good clinical results treating them with posterior-stabilized (PS) total knee arthroplasty (TKA) sacrificing both ligaments. In cases of osteoarthritis with mucoid degenerated ACL, PS TKA should be considered, sacrificing both cruciate ligaments, because mucoid degeneration might expand both cruciate ligaments.

Anterior Cruciate Ligament Ganglion Cyst and Mucoid Degeneration: A Review

Mucoid degeneration and ganglion cyst are two distinct non-traumatic lesions of the anterior cruciate ligament (ACL) that most commonly occur discretely but occasionally coexist. They are relatively uncommon, and their exact aetiopathogenesis is still not clear. ACL ganglion cyst occurs more frequently among relatively younger patients compared to mucoid degeneration. They could be asymptomatic and discovered incidentally while evaluating the knee for other pathologies. Symptomatic cases of the two conditions present with nonspecific chronic pain, painful limitation of terminal flexion and extension, and mechanical block (among other symptoms), similar to that of other internal derangement pathologies of the knee. Magnetic resonance imaging is the investigation of choice, and diagnostic criteria are defined. Arthroscopic management of these conditions efficiently provides an improvement in symptoms without instability. Computed tomography scan guided aspiration is also useful in selected cases of ACL ganglion cyst. ACL ganglion cyst and mucoid degeneration should be considered in the differential diagnosis of chronic knee pain and stiffness of unspecified etiology.

Magnetic resonance imaging of degenerative changes of the posterior cruciate ligament

Background Mucoid degeneration and ganglia reflect a continuum of degenerative changes within the posterior cruciate ligament (PCL). Purpose To assess the prevalence of and radiologists' familiarity with PCL mucoid degeneration and ganglia. Material and Methods Knee magnetic resonance imaging (MRI) from July 2013 to June 2015, excluding patients who had a preceding trauma or MRI findings indicative of a prior injury, were retrospectively reviewed, with the specific request to assess degenerative changes of the PCL, by the same musculoskeletal radiologists who previously reported these examinations, and one fellow. Results A total of 692 patients entered this study. The radiologists and the fellow together identified mucoid degeneration in 34 patients (4.9%), ganglia in 14 patients (2.0%), and both in four patients (0.6%). Several patterns of PCL mucoid degeneration were identified: diffuse thickening in seven patients, partial thickening in 16 (four associated with a ganglion), longitudinal intraligamentous PCL signal-intensity abnormalities resembling a "tram track" in 15. In all cases there was increased signal intensity on fluid-sensitive sequences. In the previous reports, only three cases of PCL mucoid degeneration out of 38 (7.9%) were described, with intraligamentous PCL signal-intensity abnormalities. In the reports of the patients with degeneration and ganglia, only ganglia were described. In the previous reports, ganglia were correctly diagnosed. Conclusion Mucoid degeneration of the PCL is much more common than previously assumed and is underestimated by radiologists.

A Systematic Summary of Systematic Reviews on the Topic of the Anterior Cruciate Ligament

BACKGROUND

There has been a substantial increase in the amount of systematic reviews and meta-analyses published on the anterior cruciate ligament (ACL).

PURPOSE

To quantify the number of systematic reviews and meta-analyses published on the ACL in the past decade and to provide an overall summary of this literature.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review of all ACL-related systematic reviews and meta-analyses published between January 2004 and September 2014 was performed using PubMed, MEDLINE, and the Cochrane Database. Narrative reviews and non-English articles were excluded.

RESULTS

A total of 1031 articles were found, of which 240 met the inclusion criteria. Included articles were summarized and divided into 17 topics: anatomy, epidemiology, prevention, associated injuries, diagnosis, operative versus nonoperative management, graft choice, surgical technique, fixation methods, computer-assisted surgery, platelet-rich plasma, rehabilitation, return to play, outcomes assessment, arthritis, complications, and miscellaneous.

CONCLUSION

A summary of systematic reviews on the ACL can supply the surgeon with a single source for the most up-to-date synthesis of the literature.

Relationship between Mucoid Degeneration of the Anterior Cruciate Ligament and Posterior Tibial Slope in Patients with Total Knee Arthroplasty

Purpose

The purpose was to analyze the relationship between posterior tibial slope (PTS) and mucoid degeneration of the anterior cruciate ligament (ACL) in patients with total knee arthroplasty.

Materials and Methods

Four hundred and twenty-four patients (24 males and 400 females; 636 knees) who received total knee arthroplasty for osteoarthritis were included. Their mean age was 68.9 years (range, 48 to 88 years). The patients were classified into three groups according to the status of ACL; normal ACL group (group I), mucoid degeneration of ACL group (group II) and ruptured or absent ACL group (group III). Plain lateral radiographs were used to measure the PTS and the values were compared among groups.

Results

There were no significant differences with regard to gender, age and left-to-right side ratio among groups (p>0.05). The mean PTS was 9.9° (range, 0.6° to 20.1°) in group I (161 knees), 10.8° (range, 0.2° to 21.8°) in group II (342 knees) and 12.3° (range, 2° to 22.2°) in group III (133 knees), which showed significant differences (p<0.001).

Conclusions

The patients with mucoid degeneration of the ACL and those with ruptured or absent ACL had greater PTS than those with normal ACL. These findings suggest that an increased PTS may be one of the causative factors for mucoid degeneration of the ACL.

Early reconstruction should be considered in younger patients with symptomatic mucoid degeneration of the anterior cruciate ligament

Background

Mucoid degeneration of the anterior cruciate ligament (ACL) is mostly observed in middle-aged patients with knee pain and limited range of motion. Although arthroscopic resection of the degenerated ACL is the treatment of choice following the failure of conservative management, the extent of the excision and subsequent ACL reconstruction for postoperative knee instability remains controversial.

Case reports

We present four cases of mucoid degeneration of the ACL in patients aged <40 years, and suggest a suitable treatment strategy for younger patients. All four patients (mean age, 33.8 years) were diagnosed with mucoid degeneration of the ACL based on characteristic clinical symptoms and magnetic resonance imaging. Arthroscopic resection of the affected portion of the ACL was performed as follows: partial resection in two cases with limited hypertrophy, and total ACL resection in the remaining two cases with degeneration involving the entire ligament. Preoperative symptoms disappeared in all cases after resection of the lesions. In the two patients with partial resection, the ACL was completely torn during subsequent sports activities despite showing no symptoms of instability for 2 years postoperatively. All four patients, including the two treated by total resection, underwent ACL reconstruction using an autogenous hamstring tendon.

Conclusion

Considering the rupture of residual ACL fibres after partial resection and the inevitability of total ACL resection due to degeneration of the entire ligament, ACL reconstruction should be considered in younger patients with symptomatic mucoid degeneration of the ACL.

Clinical significance of T2*-weighted gradient-echo MRI to monitor graft maturation over one year after anatomic double-bundle anterior cruciate ligament reconstruction: a comparative study with proton density-weighted MRI

PURPOSE

This study examined the feasibility of T2*-weighted imaging (T2*WI) gradient-echo MRI to reflect actual function of the graft after anatomic double-bundle ACL reconstruction. T2*WI and proton density-weighted imaging (PDWI) were compared in the assessment of ACL grafts.

METHOD

Sixty-one patients underwent T2*WI and PDWI at 3, 6, and 12 months postoperatively. Signal intensity of the anteromedial bundle (AMB) or posterolateral bundle (PLB) graft standardized to the intensity of the PCL was defined as signal intensity ratio (SIR). Correlations between degree of knee instability and SIR were assessed for each bundle, each time point, and each sequence. The diagnostic efficacy of T2*WI sequence to detect poorly functioning knee with anteroposterior translation ≥ 4 mm was assessed.

RESULTS

Significant correlations were observed between SIR and KT values for both AMB and PLB at 12 months on T2*WI (r=0.39 and 0.53, respectively), but not on PDWI. Notably, 9 of 10 patients with poorly functioning graft showing anteroposterior translation ≥ 4 mm at 12 months formed an isolated group with high T2*WI-SIR. Six of the 10 patients displayed an increase in SIR from 6 to 12 months. Defining anteroposterior translation ≥ 4 mm at 12 months as the diagnostic standard for poorly functioning graft, increasing T2*WI-SIR offered 60% sensitivity and > 90% specificity.

CONCLUSIONS

ACL graft intensity on T2*WI is more strongly associated with actual function of the graft than that on PDWI. An increasing trend in T2*WI-SIR from 6 to 12 months postoperatively represents a possible surrogate indicator for poorly functioning grafts.

Mucoid degeneration of the anterior cruciate ligament: Management and outcome

BACKGROUND

Mucoid degeneration (MD) is a rare pathological affection of the anterior cruciate ligament (ACL). Mucinous material within the substance of ACL produces pain and limited motion in the knee. This series describes the clinicoradiological presentation of patients with mucoid ACL, partial arthroscopic debridement of ACL and outcomes.

MATERIALS AND METHODS

During a period of 3 years, 11 patients were included based upon the clinical suspicion, magnetic resonance imaging (MRI) findings, arthroscopic features and histopathologic confirmation of MD of ACL.

RESULT

Six patients were male and five were female with median age of 40 years (range 21-59 years). All patients complained of knee pain with median duration of 5 months (range 1-24 months). All patients had painful deep flexion with 63.6% (N = 7) reporting trivial trauma before the onset of symptoms. MRI revealed MD of ACL in all with associated cyst in three patients. Partial debridement of ACL was done in ten and complete in one patient. None of them required notchplasty. Histopathology confirmed the diagnosis in all of them. At the mean followup of 13.81 months (range 6-28 months), all patients regained complete flexion and none complained of instability.

CONCLUSION

Prior knowledge of condition with high index of suspicion and careful interpretation of MRI can establish the diagnosis preoperatively. It responds well to partial debridement of ACL and mucinous material without development of instability.

A novel core biopsy technique for anterior cruciate ligament preserves ligament structural integrity: a porcine study

PURPOSE

The objective of this study was to validate a new technique to safely obtain core biopsy specimens of the anterior cruciate ligament (ACL) without jeopardizing the ACL's biomechanical properties.

METHODS

Eleven pairs of fresh porcine femur-ACL-tibia complexes were tested in a loading frame. The ACL of one knee was biopsied using a spring-loaded core biopsy device, whereas the contralateral ACL was tested as the control. Biomechanical properties of the biopsied and control ACLs were compared.

RESULTS

The ultimate load to failure was 1,202 N ± 171.1 N and 1,193 N ± 228.7 N (P = .8984) for biopsied and non-biopsied ACLs, respectively. No significant differences were noted for maximal elongation at failure, maximal strain, absorbed energy, and stiffness between biopsied and non-biopsied ACLs.

CONCLUSIONS

The results of this study indicate that a new ACL core biopsy technique can be performed while preserving the ligament's structural integrity.

CLINICAL RELEVANCE

The presented core biopsy technique could be regarded as a dedicated tool to elucidate the poorly understood (patho)biological processes occurring in both the native and reconstructed ACLs.

Reduction plasty for hypertrophic anterior cruciate ligament mucoid degeneration: clinical and knee laxity outcomes in 23 cases

INTRODUCTION

The best treatment for anterior cruciate ligament (ACL) mucoid degeneration remains open to debate. Current options are total or partial ACL resection, or a more conservative strategy, reduction plasty. The goal of this study was to retrospectively evaluate the effects of reduction plasty for ACL hypertrophy due to mucoid degeneration from clinical outcome and knee laxity points of view.

MATERIALS AND METHODS

Arthroscopy was carried out on 23 knees (21 patients) to perform a circular volume reduction plasty of the ACL, while preserving the greatest number of ligament fibers. Notchplasty was not performed. All the patients were seen again with an average follow-up of 32 months (range 8-70).

RESULTS

All the knees except three had symmetric postoperative flexion. Three patients still had pain. No patient reported having subjective feelings of instability. Among the 20 knees tested with the GNRB(TM) knee laxity measurement device, one knee had a 2.4mm difference in laxity and three had between 3 and 4mm of difference; 16 knees had no residual laxity.

DISCUSSION

Treatment of ACL mucoid degeneration by reduction plasty leads to complete pain relief in 80% of cases while maintaining good postoperative knee stability.

LEVEL OF EVIDENCE

Level IV. Retrospective study.

Report of ganglion cyst in the anterior cruciate ligament of a 6-year-old child

BACKGROUND

Intra-articular ganglion cysts of the knee are extremely rare within the pediatric population. To our knowledge, only seven case reports have been published in the medical literature identifying pediatric patients with intra-articular cysts of the anterior cruciate ligament (ACL). Intra-articular cysts of the knee are a rare cause of knee discomfort and mechanical symptoms such as locking of the knee. To our knowledge, up until now the youngest patient reported in the medical literature with an intra-articular ganglion cyst of the ACL was a 7-year-old boy.

CASE REPORT

We describe a 6-year-old boy who presented with a unilateral intra-articular ganglion cyst of the ACL in the right knee. In addition to the diagnostic work-up of radiographs and MRI, the cyst was successfully treated with arthroscopic resection and debridement to decompress the cyst.

CLINICAL RELEVANCE

We provide a review of the proposed pathogenesis, diagnostic modalities, differential diagnosis, treatment options, and complications of treatment for intra-articular cysts of the ACL.

LEVEL OF EVIDENCE

Level V, case report.

Symptomatic mucoid degeneration of the anterior cruciate ligament

PURPOSE

Mucoid degeneration of the anterior cruciate ligament (ACL) is a little-known entity. The aim of this study was to detail the clinical, radiological, arthroscopic and pathological findings of this condition and to report clinical outcomes following arthroscopic partial excision of the ACL.

METHODS

Between 1999 and 2009, 80 knees in 78 patients were diagnosed as having mucoid degeneration of the ACL based on MRI and clinical findings, and subsequently underwent arthroscopic treatment. Of these, 68 knees in 66 patients, with a median age of 51 years (range, 35-75 years), were followed-up for at least one year.

RESULTS

All patients had insidious onset of knee pain, while 56 knees (82 %) had associated extension deficits and 36 knees (53 %) had restricted flexion. MRI findings typically showed diffuse thickening and increased signal intensity of the ACL. Arthroscopic examination revealed notch impingement and bulging of hypertrophied ACL into lateral compartments. Associated lesions included meniscal tears in 33 knees and chondral lesions of at least Outerbridge grade 2 in 56 knees. All knees underwent arthroscopic partial excision of the hypertrophied ACL, with three undergoing preoperative and 30 undergoing concomitant meniscectomies. Pain relief was achieved in 58 of 62 knees (94 %) following partial excision of the ACL. Extension deficits were normalized in 49 of 56 knees (88 %), and restricted flexion was normalized in 33 of 36 affected knees (92 %). Four knees of four patients had postoperative symptoms of anterior instability.

CONCLUSIONS

Pain and limitation of motion due to mucoid degeneration of the ACL can be improved by arthroscopic partial excision of the ACL with or without notchplasty. However, one potential complication is the development of postoperative symptoms of anterior instability.

LEVEL OF EVIDENCE

Retrospective study, Level IV.

Histopathological changes in the human posterior cruciate ligament during aging and osteoarthritis: correlations with anterior cruciate ligament and cartilage changes

OBJECTIVES

To determine the histological patterns of posterior cruciate ligament (PCL) degeneration during aging and in relation to changes in articular cartilage and anterior cruciate ligament (ACL) across the entire adult age spectrum.

METHODS

Human knee joints (n=120 from 65 donors) were processed within 72 h of postmortem. Articular cartilage surfaces were graded macroscopically. Each PCL was histologically evaluated for inflammation, mucinous changes, chondroid metaplasia, cystic changes and orientation of collagen fibres. The severity of PCL degeneration was classified as normal, mild, moderate or severe. PCL scores were compared to ACL and cartilage scores from the same knees.

RESULTS

All knees had intact PCL. Histologically, 6% were normal, 76% showed mild, 12% moderate and 9% severe degeneration. Fibre disorientation was the most prevalent and severe change. Histological grades of PCL and ACL correlated, but significantly fewer PCL than ACL showed severe changes. There was a weaker correlation between aging and total histological PCL scores (R=0.26) compared to aging and ACL scores (R=0.42). ACL scores correlated with cartilage scores (R=0.54) while PCL scores increased with the severity of osteoarthritis from grades 0 to III but not between osteoarthritis grades III-IV (R=0.32). In knees with ruptured ACL, the PCL scores correlated with cartilage scores of the lateral compartment.

CONCLUSIONS

PCL histopathological changes were less severe than in the ACL. PCL degeneration was associated with ACL and cartilage damage. The lack of correlation with age indicates independent pathways for PCL versus ACL degeneration.