Cyclops Lesions of the Knee: A Narrative Review of the Literature

MRI sequences at different degrees of flexion to investigate knee popping: an unusual way to diagnose an isolated pigmented villonodular synovitis lesion

Knee popping is a frequent symptom among knee disorders which requires further investigation in case of a recent evolution of the symptom or pathological associated ones. This article reports a rare presentation of pigmented villonodular synovitis (PVNS), identified as the cause of knee popping symptoms, by performing MRI sequences at various degrees of knee flexion for a patient complaining from a gradual onset of knee popping, occurring when bending the knee over 120° of flexion. MRI sequences were performed just before the popping occurs (flexion 90°) and right after it had occurred (flexion 120°). The latter confirmed the origin of the symptom as the lesion moved forward, passing brutally through the interstice between the PCL and the ACL at 120° of flexion, explaining the popping. Treatment decision was to perform an arthroscopic resection of the lesion. Diagnosis of isolated PVNS was confirmed after anatomopathological analysis.

Recurrent cyclops lesion after primary resection of fibroreactive nodule following anterior cruciate ligament reconstruction

In this case report featured in World Journal of Orthopedics, Kelmer et al describe a rare finding of a 28-year-old female patient who presented with a recurrent fibroreactive nodule 7 months following the resection of a primary cyclops lesion, suggesting recurrent cyclops syndrome. The patient had undergone an initial anterior cruciate ligament reconstruction for a non-contact right knee injury and reported successful recovery. Two years later, the patient sustained a repeat right knee injury followed by a positive McMurray test and acute pain with terminal extension. Arthroscopic synovectomy confirmed magnetic resonance imaging (MRI) finding of a cyclops lesion, which was surgically removed. Seven months postoperatively, the patient reported stiffness and difficulty with terminal extension. Repeat MRI indicated a recurrent cyclops lesion, which was surgically resected. Following resection of the second lesion, the patient underwent physical therapy and achieved full range of motion, maintaining complete recovery 19 months postoperatively. Recurrent cyclops lesions have rarely been reported in the literature, and this article is novel in its report of recurrent cyclops syndrome following a bone-patellar tendon-bone allograft. The presentation of this unusual finding exposes a need for further investigation of cyclops lesion pathology, which will aid its prevention and treatment.

Influence of female sex and double-quadruple semitendinosus-gracilis graft on the incidence of postoperative symptomatic cyclops lesions after ACL reconstruction

PURPOSE

Risk factors for the development of symptomatic cyclops lesion after anterior cruciate ligament reconstruction (ACLR) surgery are not entirely identified yet. This study aimed to investigate whether the choice of hamstring graft (semitendinosus-gracilis; STG vs. semitendinosus; ST) affects the risk of developing a symptomatic cyclops lesion after ACLR.

METHODS

This retrospective cohort study included 1416 patients receiving either an ST graft (n = 1209) or an STG graft (n = 207) ACLR with a follow-up of at least 2 years. A persisting extension limitation was clinically determined, and cyclops lesions were confirmed by magnetic resonance imaging (MRI) and second-look arthroscopy. Graft-specific incidence of cyclops lesions was examined with χ2 test and combined with the factors number of graft bundles, graft diameter and sex evaluated with a binominal logistic regression model.

RESULTS

In total, 46 patients developed symptomatic cyclops lesions (3.2%), with 36 having ACLR with an ST graft (3.0%) and 10 with an STG graft (4.8%) (n.s). The mean time from ACLR to the second-look arthroscopy for cyclops removal was 1.1 ± 0.6 years. Female patients were 2.5 times more likely to develop a cyclops lesion than male patients. Patients with an STG graft and larger graft diameters did not have a higher risk of developing cyclops lesions. Patients who received an STG graft with both tendons folded four times (double-quadruple) had significantly higher risk of developing a cyclops compared with all other numbers of graft bundles combined (8.3%, respectively 3.0%; p = 0.014).

CONCLUSION

This study could not prove an increased risk of developing a symptomatic cyclops lesion for patients with an STG graft compared with an ST graft used for ACLR. However, patients with a double-quadruple ACLR had a higher percentage of cyclops lesions compared with all other numbers of graft bundles. Female sex was associated with an increased risk of developing cyclops lesions.

LEVEL OF EVIDENCE

Level III.

Female Sex, Older Age, Earlier Surgery, Anticoagulant Use, and Meniscal Repair Are Associated With Increased Risk of Manipulation Under Anesthesia or Lysis of Adhesions for Arthrofibrosis After Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To determine what patient or surgical factors are associated with an increased risk of arthrofibrosis requiring manipulation under anesthesia (MUA) or lysis of adhesions (LOA) after anterior cruciate ligament reconstruction (ACLR).

METHODS

A systematic review was performed in adherence to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Cochrane, Embase, and Medline databases were searched for studies published through February 2023. Inclusion criteria were studies that identified risk factors for MUA and/or LOA after ACLR. Studies investigating arthrofibrosis after multiligamentous knee injuries or ACL repair were excluded.

RESULTS

Eleven studies including a total of 333,876 ACLRs with 4,842 subsequent MUA or LOA (1.45%) were analyzed. Increasing age was associated with an increased risk in 3 studies (P < .001, P < .05, P < .01) but was found to have no association another two. Other factors that were identified by multiple studies as risk factors for MUA/LOA were female sex (4 studies), earlier surgery (5 studies), use of anticoagulants other than aspirin (2 studies), and concomitant meniscal repair (4 studies).

CONCLUSIONS

In total, 1.45% of the patients who underwent ACLR and were included in this systematic review had to undergo a subsequent MUA/LOA to treat arthrofibrosis. Female sex, older age, earlier surgery, use of anticoagulants other than aspirin, and concomitant meniscal repair were associated with increased risk of MUA/LOA. The modifiable risks, including use of anticoagulants and time between injury and surgery, can be considered when making treatment decisions.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III-IV studies.

Cyclops syndrome following anterior cruciate ligament reconstruction: Can relapse occur after surgery?

Symptomatic cyclops lesions are complications that can be seen at rates of up to approximately 10% after anterior cruciate ligament reconstruction. However, recurrent cyclops lesions have rarely been documented. There are case rare series in the literature regarding the treatment of recurrent cyclops lesion. Future large studies are needed to investigate factors contributing to the development of cyclops lesions and syndrome and treatment options.

Recurrent cyclops lesion after primary anterior cruciate ligament reconstruction using bone tendon bone allograft: A case report

BACKGROUND

Cyclops lesions are a known complication of anterior cruciate ligament (ACL) reconstruction, with symptomatic cyclops syndrome occurring in up to 11% of surgeries. Recurrent cyclops lesions have been rarely documented; this case study documents the successful treatment of a recurrent cyclops lesion.

CASE SUMMARY

A 28-year-old female presented following a non-contact injury to the right knee. Workup and clinical exam revealed an ACL tear, and arthroscopic reconstruction was performed. Two years later a cyclops lesion was discovered and removed via arthroscopic synovectomy. Seven months postoperatively, the patient presented with pain, stiffness, and difficulty achieving terminal extension. A smaller recurrent cyclops lesion was diagnosed, and a repeat synovectomy was performed. The patient recovered fully.

CONCLUSION

To the best of our knowledge, this is the first documented case of recurrent cyclops lesion after bone-patellar tendon-bone allograft ACL reconstruction presenting as cyclops syndrome.

Histological and clinical analysis of knee cyclops lesions

BACKGROUND AND AIM

Cyclops Syndrome, first described by Jackson and Schaefer in 1990, is known as a complication of anterior cruciate ligament reconstruction (ACLR). However further researches have demonstrated that cyclops can be present even without symptoms and/or in absence of ACLR, simply configuring itself as a lesion in patients with rupture of the native ligament.

METHODS

This is a retrospective cohort study in which we report our experience of 13 cyclops lesions found between 126 patients during a primary arthroscopic ACLR. Preoperative examination with tests of joint stability and range of movement measurement was performed and recorded. Accurate joint examination was performed during arthroscopy and the cyclops lesions found were removed and analyzed with haematoxylin-eosin coloration. Post-operative clinical examination was performed until 6 months of follow-up.

RESULTS

Histological analysis showed proliferation of dense fibroelastic polypoid nodules with a macroscopically histological aspects of a "blue eye", hence the name Cyclops. At 6 months of follow-up after surgery, none of the patients reported pain at terminal extension or instability and they were all able to resume their previous activities.

CONCLUSIONS

Our study confirmed that surgical reconstruction of the ACL is not the only condition in which the Cyclops Syndrome develops; in fact our histological analysis indicate that the Cyclops lesions develop like a reactive fibroproliferative process following the rupture of the native ACL fibers, as scar reaction to the trauma: for this reason an accurate arthroscopic detection of these Cyclops lesions is crucial during primary ACL reconstruction in order to obtain the best surgical outcomes.

Less than 1% risk of donor-site quadriceps tendon rupture post-ACL reconstruction with quadriceps tendon autograft: a systematic review

PURPOSE

The purpose of this study is to develop a comprehensive complications profile for quadriceps tendon-autograft anterior cruciate ligament reconstruction (QT ACL-R).

METHODS

A traditional and grey literature search was conducted in accordance with PRISMA and R-AMSTAR guidelines. PubMed, EMBASE, MEDLINE, CINAHL, Cochrane, Web of Science, and many grey literature sources were searched from inception to May 29, 2022. All studies were searched and screened in duplicate with included studies being of all levels of evidence, reporting complications, and with patients of all ages undergoing primary ACL reconstruction with quadriceps tendon autograft in the last 15 years. Studies were excluded if they had cadaveric or animal subjects or were reviews. Risk of bias assessment was conducted using MINORS criteria for non-randomised studies and Cochrane's RoB 2.0 for randomised studies. Data were summarised with weighted event rates generated under a random-effects model.

RESULTS

A total of 55 studies (5315 reconstructions) were included: 32 used quadriceps tendon with bone block (B-QT), 19 used all-soft tissue quadriceps tendon (S-QT), and four did not report the QT graft subtype used. Included patients had an age range of 6.2-58 years and an average reported follow-up time of 28.1 months (range, 6-90 months) for non-randomised studies and 34.3 months (range, 0.233-120 months) for randomised studies. Pooled incidence rates for clinically relevant major complications included contralateral ACL injury at 6.0%, postoperative meniscal issues at 5.4%, cyclops lesions at 4.8%, graft failure at 4.1%, patellar fracture at 2.2%, hardware removal at 1.7%, infection at 1.5%, and donor-site quadriceps tendon rupture at 0.7%. Pooled incidence rates for clinically relevant minor complications included anterior knee pain at 9.7%, kneeling pain at 9.5%, sensation deficits at 4.4%, loss of extension at 4.2%, donor-site tendinopathy at 3.9%, cosmetic issues at 1.8%, and hematoma at 1.5%.

CONCLUSIONS

QT ACL-R resembles other graft types in its rates and types of postoperative complications. In this exploratory systematic review, no complications of QT ACL-R were found to be disproportionately represented in the literature. This graft type should remain an option with comparable complication rates to other graft choices.

LEVEL OF EVIDENCE

Level IV.

REGISTRATION

This study was preregistered under PROSPERO with preregistration code CRD42022302078.

Association of COVID-19 Lockdown With Increased Rate of Cyclops Syndrome in Patients With Unexpected Home-Based Self-Guided Rehabilitation After ACL Reconstruction

Background

The risk of cyclops syndrome increases significantly after anterior cruciate ligament (ACL) reconstruction (ACLR) if complete extension is not recovered before the sixth postoperative week. The lockdown in France due to the COVID-19 pandemic led to an absence of supervised rehabilitation, requiring unexpected self-rehabilitation in patients who underwent ACLR just before lockdown.

Purpose

To determine the rate of cyclops syndrome after ACLR in patients who underwent self-rehabilitation during lockdown.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 75 patients receiving a hamstring graft for ACLR during the COVID-19 pandemic between February 10, 2022, and March 16, 2020, carried out self-rehabilitation during part of their first 6 postoperative weeks using exercise videos on a dedicated website. Clinical examination was performed at a minimum 1-year follow-up with International Knee Documentation Committee (IKDC), Lysholm, Tegner, and ACL-Return to Sport after Injury (ACL-RSI) scores. This group was compared with a matched-pair control group of 72 patients who underwent surgery in 2019 and completed postoperative supervised rehabilitation with a physical therapist. Rates and reasons for second surgery (arthrolysis, meniscal procedure) were also recorded.

Results

In the COVID group (n = 72; 3 patients were lost to follow-up), the mean follow-up was 14.5 ± 2.1 months (range, 13-21) and rate of reoperation for clinical cyclops syndrome was 11.1% (n = 8). The rate of cyclops syndrome was significantly lower (1.4%) in the control group (P = .01). In the COVID group, 8 patients underwent anterior arthrolysis at a mean of 8.6 months after the primary surgery, and 4 patients underwent another surgical intervention (meniscal procedure [n = 3], device removal [n = 1]). In the COVID group, mean Lysholm was 86.6 ± 14.1 (range, 38-100), Tegner was 5.6 ± 2.3 (range, 1-10), subjective IKDC was 80.3 ± 14.7 (range, 32-100) and ACL-RSI score was 77.3 ± 19.7 (range, 33-100).

Conclusion

The rate of cyclops syndrome after ACLR was significantly greater in the COVID group versus the matched controls. The dedicated website was not effective at supporting self-guided rehabilitation and could benefit from interactive improvements so it is at least as effective as supervised rehabilitation.

An analysis of the incidence, risk factors, and timing of development of cyclops lesions after anterior cruciate ligament reconstruction

BACKGROUND

Cyclops lesions are a known complication following anterior cruciate ligament reconstruction (ACLR) with a described incidence between 1.9% to 10.9%. The objective of this study was to identify the incidence, timing, and variables that correlated with development of a cyclops lesion, and if objective functional testing differed between patients with and without cyclops lesions.

METHODS

313 consecutive patients who underwent ACLR and participated in Lower-Extremity Assessment Protocol (LEAP) testing at a single, academic institution were analyzed. Retrospective chart review was performed to identify patient demographic factors, medical comorbidities, and potential peri-operative risk factors. Postoperative functional outcome metrics and patient reported outcomes were collected per the institution's LEAP testing protocol. Binary logistic regression was utilized to identify risk factors for cyclops lesions. Objective functional outcomes and patient reported outcomes were compared between patients with and without cyclops lesions.

RESULTS

23/313 (7.35%) patients developed a cyclops lesion following ACLR, of which 17 (73.91%) were found to be symptomatic. Concomitant meniscal repair correlated with an increased likelihood of developing a cyclops lesion (p = 0.040); no other risk factors significantly differed between cohorts. There were no clinically relevant extension deficits or differences in objective functional performance measures at six months post-operatively between study cohorts.

CONCLUSIONS

Concomitant meniscal repair may be associated with the development of cyclops lesions due to restrictive postoperative range of motion protocols; however no other pre- or intra-operative factors demonstrated significant correlation. Presence of a cyclops lesion should be considered with late loss of knee extension after ACLR.

Bone-patellar tendon-bone autograft and female sex are associated with the presence of cyclops lesions and syndrome after anterior cruciate ligament reconstruction

PURPOSE

Associated risk factors for the development of cyclops lesions have been little. Investigated, because most previous studies have limited their research to cases with symptomatic cyclops lesions (cyclops syndrome). The purpose of this study was to evaluate the presence of cyclops lesions using magnetic resonance image (MRI) at 6 and 12 months after anterior cruciate ligament reconstruction (ACL-R), and to investigate the associated risk factors of cyclops lesions and syndrome.

METHODS

A retrospective analysis of patients who underwent ACL-R using bone-patellar tendon-bone (BTPB) or hamstring tendon autograft from 2008 to 2017 was conducted. Predictor variables (age, sex, body mass index [BMI], time from injury to ACL-R, preinjury Tegner activity score, graft, meniscal and cartilage injury, and notch width index on MRI for the presence of cyclops lesions and syndrome were analyzed with multivariate logistic regression.

RESULTS

Four hundred and fifty-five patients (225 males and 230 females) were enrolled. One hundred and four patients (22.9%) had cyclops lesions, and all cyclops lesions were detected on MRI at 6 months post-operatively. In addition, 20 patients (4.4%) had cyclops syndrome which means that these were symptomatic cases. The risk factors for presence of cyclops lesions were BPTB autograft (OR = 2.85; 95% CI 1.75-4.63; P < 0.001) and female sex (OR = 2.03; 95% CI 1.27-3.25; P = 0.003). The presence of cyclops syndrome increased with graft (BPTB) (OR = 18.0; 95% CI 3.67-88.3; Powered by Editorial Manager^® and ProduXion Manager^® from Aries Systems Corporation P < 0.001), female sex (OR = 3.27; 95% CI 1.07-10.0; P = 0.038), and increased BMI (OR = 1.21; 95% CI 1.05-1.39; P = 0.008).

CONCLUSIONS

All cyclops lesions were detected 6 months after ACL-R, and the majority of them were asymptomatic. BPTB autograft and female sex were the significant risk factors for the presence of cyclops lesions and syndrome. In addition, increased BMI was associated with a higher risk of developing cyclops syndrome. When BPTB autograft is used for a female patient, full active knee extension should be encouraged in the early period after ACL-R to prevent cyclops lesion formation.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Occurrence Rate of Cyclops Lesion After Anatomic Double-Bundle ACL Reconstruction: Comparison Between Remnant Tissue Preservation and Resection Methods

Background

The occurrence rate of cyclops lesion after anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with remnant tissue preservation remains unclear.

Hypothesis

The study hypotheses were as follows: (1) the occurrence rate of cyclops lesion will be comparable between the remnant-preserving and remnant-resecting ACL reconstruction methods, and (2) there will be no significant differences in clinical outcomes between the remnant-preserving and remnant-resecting procedures.

Methods

This retrospective comparative study involved 177 patients who underwent unilateral anatomic double-bundle ACL reconstruction using hamstring tendon autografts from 2014 to 2018 at our hospital. According to the Crain classification of ACL remnant tissue, 98 patients with remnant types I, II, or III underwent the remnant-preserving procedure (group A), and the remaining 79 patients with remnant type IV underwent the remnant-resecting procedure (group B). All patients underwent second-look arthroscopy. Patients were evaluated according to arthroscopic and clinical results at postoperative 15.2 ± 8.4 months (mean ± SD). Statistical comparisons between groups were made using the paired Student t test, chi-square test, and Fisher exact test.

Study Design

Cohort study; Level of evidence, 3.

Results

At second-look arthroscopy, the incidence of cyclops lesions was significantly higher in group B than in group A (29.1% vs 13.3%; P = .0139). Cyclops lesions were divided into 4 locations: femoral side (type 1), midsubstance (type 2), tibial side (type 3), and anterior (type 4) of the ACL graft. The ratio of the tibial-side cyclops lesion (type 3) was significantly higher in group B than in group A (P = .0354). There were no significant differences in the clinical evaluation scores between the procedures. Side-to-side anterior laxity was significantly less in group A than in group B (0.7 vs 1.6 mm; P = .0035). Concerning postoperative laceration and synovium coverage of the grafts, group A was significantly better than group B (P < .0001).

Conclusion

In this cohort of patients undergoing double-bundle ACL reconstruction, resection of the ACL remnant was associated with a significantly higher rate of cyclops lesion formation when compared with preservation of the remnant.

Cyclops lesions associated with both bundles and selective bundle repair of the anterior cruciate ligament

BACKGROUND

The remnant of a ruptured anterior cruciate ligament (ACL) can increase the risk of impingement or a cyclops lesion, which can increase challenges to proper tunnel placement.

PURPOSE

To evaluate the prevalence of cyclops lesions after ACL reconstruction and to assess the difference in the incidence of cyclops lesions between single-bundle repair and selective bundle repair of the ACL.

MATERIAL AND METHODS

This retrospective study included 151 patients who were diagnosed with an ACL tear after knee joint magnetic resonance imaging (MRI) who underwent ACL reconstruction surgery. MRI diagnosis of cyclops lesion formation was made if a soft-tissue mass was seen anteriorly in the intercondylar notch near the tibial insertion of the reconstructed ACL, based on sagittal T2-weighted (T2W) imaging. The size of the cyclops lesions was recorded as the largest diameter on the sagittal T2W imaging.

RESULTS

A cyclops lesion was detected in 74 (38.5%) cases. Cyclops lesions were detected more frequently in cases with single-bundle repair of the ACL, but the results were not statistically significant (P = 0.609). Compared with selective bundle repair, cyclops lesions had a significantly higher prevalence in the posterolateral (PL) bundle repair than in the anteromedial (AM) bundle repair (P = 0.027) based on MR images at 6-12 months after surgery.

CONCLUSION

The incidence of cyclops lesions did not differ significantly in single-bundle repair and selective bundle repair of ACL. However, selective PL bundle repair of the ACL showed a significantly increased incidence of cyclops lesions compared with selective AM bundle repair.

Selective bundle versus complete anterior-cruciate ligament reconstruction: A systematic review and meta-analysis

Purpose

Selective bundle reconstruction (SLB) refers to preservation of the intact bundle and reconstruction of the ruptured bundle in a partial tear while complete ACL reconstruction involves the removal of all remnant tissue and reconstruction of one or both bundles. As the evidence for SLB versus complete ACL reconstruction remains unclear, this study aimed to compare the two techniques. This study's hypothesis was that SLB reconstruction allows better function and stability compared to complete ACL reconstruction.

Methods

A systematic search of PubMed, EMBASE, Scopus and Cochrane Library was conducted, identifying studies that compared SLB ('selective' group) versus complete ('complete' group) ACL reconstruction. Meta-analysis was conducted for post-operative functional scores, stability outcomes and complications as well as pre-operative to post-operative change.

Results

Eleven studies were included in the meta-analysis, with 1107 patients and a pooled mean follow-up of 29.5 months. Post-operatively, the Selective group had significantly reduced anterior laxity, shown by a lower mean arthrometry side-to-side difference (p<0.01). Analysis of change results showed that the Selective group had a lower mean improvement in arthrometry side-to-side difference as well (p<0.01). No significant difference was shown for all other post-operative outcomes.

Conclusion

This study provides valuable insight to the management of partial tears. It has demonstrated that the preservation of the intact bundle offers stability and function that is as good as complete reconstruction and that SLB is a potentially viable option in the management of partial tears.

Level of evidence

Meta-analysis; Level of evidence, 4.

Quadriceps Tendon Anterior Cruciate Ligament Reconstruction: A Systematic Review of Postoperative Rehabilitation and Complication Profiles

PURPOSE

The purposes of this study are to explore current elements for postoperative rehabilitation protocol after quadriceps tendon-anterior cruciate ligament reconstruction (QT-ACLR), outline general timelines for progression of those elements, and explore their associated complication rates and profiles.

METHODS

In accordance with PRISMA guidelines, 5 online databases (EMBASE, MEDLINE, CINAHL, Cochrane, and PubMed) were searched and screened in duplicate using predetermined criteria for studies on the aforementioned patient population. Descriptive statistics are presented.

RESULTS

A total of 56 studies were included, with 31 studies using quadriceps tendon with bone block (B-QT) and 26 studies using all-soft tissue quadriceps tendon (S-QT). The majority of studies permitted full weightbearing and range of motion (ROM) within the first 12 postoperative weeks, and motion-controlled braces within 6 weeks. Isometric exercises were initiated within 1 week after surgery, closed-chain exercises within 12 weeks, and open-chain and sports-specific exercises within 36 weeks. Complication profiles were similar between graft types and included graft failure (1.2%-1.6%), cyclops syndrome (0.4%-0.7%), and persistent stiffness (0.9%).

CONCLUSIONS

Current postoperative rehabilitation strategies in ACLR with QT offer a complication profile comparable to those reported with other graft types. Based on the included rehabilitation regimen, these protocols should focus on early ROM, specifically on achieving full extension, alongside isometric quadriceps strengthening. Progression to closed- and open-chain exercises should follow in a progressive manner, similar to existing protocols in ACLR. Adjuncts such as motion-controlled bracing and continuous passive motion machines may be used if graft protection is prioritized. This review highlights the need for comparison of defined protocols against one another in the setting of QT-ACLR.

LEVEL OF EVIDENCE

IV, systematic review of Level I-IV studies.

Excision of a Knee Cyclops Lesion Using a Needle Arthroscope

After anterior cruciate ligament (ACL) reconstruction surgery, achieving full range of motion and strength of the postoperative knee is critical for optimal surgical outcomes. Abnormal tissue growth and scar formation in the postoperative knee can create a block to terminal extension of the knee. Cyclops lesions are areas of granulation tissue with neovascularization and fibrous tissue formation peripherally, most commonly at the anterolateral aspect of the tibial graft site after ACL reconstruction. When these lesions block terminal extension and cause mechanical symptoms, cyclops syndrome is diagnosed, and secondary knee arthroscopy is often performed to remove this tissue to allow for full range of motion. This Technical Note describes a minimally invasive approach with the NanoScope. The NanoScope allows for decreased postoperative pain and swelling with a likely quicker recovery back to normal postoperative therapy.

Adolescent Quadriceps Tendon Rupture, an Early Complication After ACL Reconstruction: A Case Report

CASE

A healthy adolescent male patient initially presented with complete rupture of the anterior cruciate ligament (ACL) after a plant-twist injury during a high school football game. Four weeks after ACL reconstruction with autograft bone-patella tendon-bone, the patient slipped and fell, sustaining hyperflexion of the knee, resulting in rupture of the ipsilateral quadriceps tendon.

CONCLUSION

Although this rare complication has previously been reported in the adult population, to the best of our knowledge, this is the first known report of an adolescent patient sustaining a quadriceps tendon rupture after ACL reconstruction.

A Multi-Systems Approach to Human Movement after ACL Reconstruction: The Musculoskeletal System

Several negative adaptations to the musculoskeletal system occur following anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) such as arthrogenic muscle inhibition, decreased lower extremity muscle size, strength, power, as well as alterations to bone and cartilage. These changes have been associated with worse functional outcomes, altered biomechanics, and increased risk for re-injury and post-traumatic osteoarthritis. After ACL injury and subsequent ACLR, examination and evaluation of the musculoskeletal system is paramount to guiding clinical decision making during the rehabilitation and the return to sport process. The lack of access many clinicians have to devices necessary for gold standard assessment of muscle capacities and force profiles is often perceived as a significant barrier to best practices. Fortunately, testing for deficits can be accomplished with methods available to the clinician without access to costly equipment or time-intensive procedures. Interventions to address musculoskeletal system deficits can be implemented with a periodized program. This allows for restoration of physical capacities by adequately developing and emphasizing physical qualities beginning with mobility and movement, and progressing to work capacity and neuromuscular re-education, strength, explosive strength, and elastic or reactive strength. Additional considerations to aid in addressing strength deficits will be discussed such as neuromuscular electrical stimulation, volume and intensity, eccentric training, training to failure, cross-education, and biomechanical considerations. The American Physical Therapy Association adopted a new vision statement in 2013 which supported further development of the profession's identity by promoting the movement system, yet validation of the movement system has remained a challenge. Application of a multi-physiologic systems approach may offer a unique understanding of the musculoskeletal system and its integration with other body systems after ACLR. The purpose of this clinical commentary is to highlight important musculoskeletal system considerations within a multi-physiologic system approach to human movement following ACLR.

LEVEL OF EVIDENCE

5.