Lateral Gutter Research Articles

Influence of fixation with two vs. three screws on union of arthroscopic tibio-talar arthrodesis: Comparative radiographic study of 111 cases

BackgroundAnkle arthrodesis is a treatment of choice for advanced tibio-talar disease unresponsive to conservative treatment. Using arthroscopy to perform this procedure minimises soft-tissue trauma while providing similar outcomes to those of open surgery. Union rates have ranged across studies from 85% to 100%. The objective of this study was to assess the potential influence on union of the number of screws used for arthrodesis fixation. HypothesisThe working hypothesis was that using three screws for arthrodesis produced a higher union rate than did using only two screws. Material and methodsThis single-centre retrospective comparative study included 111 cases of arthroscopic ankle arthrodesis (in 108 patients) carried out between February 1994 and October 2012. The number of screws was two in 75 cases and three in 36 cases. Union was assessed on radiographs taken 2, 6, and 12months postoperatively. ResultsMean age at surgery was 55.8years. After 12months, union was achieved in 87.4% cases overall. The non-union rate was 16% with two screws and 5.6% with three screws. Three-screw fixation was associated with a significantly higher rate of union of the medial gutter after 6months and of the lateral gutter after 12months. DiscussionOur findings support the use of three screws for fixation of arthroscopic tibio-talar arthrodesis. Adding a third screw seems associated with a lower risk of non-union and a shorter time to union. These effects can be ascribed to greater stability of the construct. Level of evidenceLevel IV, retrospective study.

Early radiographic osteoarthritis prevalence and progression determined with different view radiographs of the hip and knee: The CHECK (Cohort Hip and Cohort Knee) study

Early radiographic osteoarthritis prevalence and progression determined with different view radiographs of the hip and knee: The CHECK (Cohort Hip and Cohort Knee) study

Technique of Arthroscopic Treatment of Impingement After Total Ankle Arthroplasty

Rates of medial and/or lateral gutter impingement after total ankle replacement are not insignificant. If impingement should occur, it typically arises an average of 17 months after total ankle replacement. Our patient underwent treatment for right ankle medial gutter bony impingement with arthroscopic debridement 5 years after her initial total ankle replacement. Standard anteromedial and anterolateral portals and a 30° 2.7-mm-diameter arthroscope were used. An aggressive soft-tissue and bony resection was performed using a combination of curettes, a 3.5-mm shaver, a 5.5-mm unsheathed burr, a drill, and a radiofrequency ablator. This case shows that arthroscopic treatment is an effective and potentially advantageous alternative to open treatment of impingement after total ankle replacement. In addition, symptoms of impingement often improve in a short amount of time after arthroscopic debridement of the medial and/or lateral gutter.

Arthroscopic Debridement After Total Ankle Arthroplasty.

Residual pain due to impingement after ankle arthroplasty can be addressed with arthroscopic debridement. Literature focusing on the effectiveness of arthroscopic debridement after total ankle arthroplasty (TAA) is scarce. The authors report a case series of 12 patients complaining of anterior or posterior impingement pain, 11 of which were in the absence of malalignment which were treated by arthroscopy. Of the 106 TAAs performed between 2003 and 2012, a total of 12 subjects reported postoperative pain resulting from anterior or anteromedial impingement, medial and/or lateral gutter impingement, posterior impingement, and/or ankylosis. All patients were reviewed on a regular basis through chart review, clinical examination, and radiologic evaluation. The average time to final follow-up was 58.8 months. The average period from the original TAA to the arthroscopic debridement was 38.2 months. The median AOFAS hindfoot score was significantly (P < .05) improved from 64.6 preoperatively to 73.5 postoperatively. Eight subjects reported good pain relief after the arthroscopic debridement, and partial pain relief was reported by 4 subjects. Three patients with painful ankylosis had no improvement in the total range of motion of the TAA implant after the arthroscopic debridement. The results suggest that arthroscopic debridement in patients with residual pain due to impingement syndromes after TAA was effective in 8 of the 12 cases at 2 years' follow-up. However, the results suggest that arthroscopic debridement in the presence of painful ankylosis associated with or without impingement syndromes results only in partial pain relief and does not improve the range of motion. Level IV, case series.

Chronic Ankle Instability and Progressing Pain - Wrestling

HISTORY: 53 year old male active former D1 wrestler presented with right ankle pain located anteriorly and anterior lateral. He has an unstable right ankle with multiple episodes of giving away for the past 15 years. Patient had a previous right ankle surgery with bone fragment removed 15 years ago, but no ligament repairs. His activities are restricted, although his goal is to be able to snow board. PHYSICAL EXAMINATION: Examination revealed restricted ROM with PF to 25 deg and DF to 10 deg. Inversion and Eversion were found to be 15 and 10 degrees.He has more soft tissue thickening and swelling over the lateral gutter. No indication of infection. Patient was tender at the lateral gutter, the talofibular ligament, calcaneofibular and mild tenderness over the peroneal’s and sinus tarsi. Anterior drawer was positive. Patient had no pain on the Achilles, negative Thompson. No pain over anterior tib/posterior tib/flex hall longus tendons. Sensations were equal and intact with good pulses present DIFFERENTIAL DIAGNOSIS: 1. Tendonitis of multiple tendon 2. DJD of ankle 3. CPPD 4. Heterotrophic calcification 5. Synovial chondromatosis TEST AND RESULTS: Right ankle AP, oblique and lateral radiographs -DJD of ankle. Unstable with varus stress bilaterally. -Severe osteochondromatosis -Anterior bone spurs MRI of right ankle/hindfoot -Moderately severe to severe degenerative OA in the tibiotalar joint -Chronic instability from ATFL rupture and chronic sprain of deltoid ligament complex -Extensive osteochondromatosis present within the ankle joint, most concentrated in the dilation of the flexor halluces longus tendon sheath -Tenosynovitis of the PT, FD, PL and FHL tendon sheaths -Mild to moderate tendinitis of PL with minimal abnormal grade 2 signal centrally within the peroneus longus tendon -Full-thickness articular cartilage loss and subchondral reactive marrow changes in the tibial plafond and talar dome. FINAL WORKING DIAGNOSIS: Extensive osteochondramatosis within the flexor halluces tendon with tenosynovitis of multiple tendons secondary to chronic ankle instability and DJD TREATMENT AND OUTCOMES: 1. Stability shoe with inserts 2. Physical therapy 3. Ankle scope with bone marrow aspiration, LCL repair, varus hind foot osteotomy, removal of loose fragments and bone spurs schedule for Dec 2014

The "lateral gutter drive-through" sign revisited: a cadaveric study exploring its real mechanism based on the individual posterolateral structure of knee joints.

Although the validity of the "lateral gutter drive-through" (LGDT) test has been proved to offer high sensitivity and specificity in diagnosing the posterolateral rotational instability of knee joints, the real mechanism on how the injury pattern of individual posterolateral knee structure triggers the positive LGDT sign still remains unknown. A certain amount of popliteus tendon (POP-T) laxity resulted from specific injury patterns of individual posterolateral knee structure or some degree of medial structural injury will lead to positive LGDT sign. Controlled laboratory study. Seven non-paired intact cadaveric knees were divided into four groups and tested under unique sequential sectioning sequences including: (1) distal POP-T and popliteofibular ligament (PFL) (n = 2); (2) PFL and distal POP-T (n = 3); (3) lateral collateral ligament (LCL), distal POP-T and PFL (n = 1); (4) superficial medial collateral ligament (sMCL), deep MCL, posterior oblique ligament (POL), anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) (n = 1). The LGDT tests and the measurements of external tibial rotational angle (ETRA) were first performed on all the intact knees and then at each time point when an additional structure was sectioned. Results of each LGDT test and the absolute value of increased ETRA compared with the intact knee were recorded. Each knee was tested at 30° of flexion. A navigation system was used to measure motion changes of the tibia with respect to the femur. Initially, the LGDT tests all showed negative on each of the intact knee. Isolated sectioning of the distal POP-T, PFL or the LCL produced increased but insignificant ETRA with the LGDT tests still negative. However, simultaneous sectioning of the distal POP-T and PFL produced significantly increased ETRA with the LGDT tests changed to positive. In addition, for the knee with medial structural injuries, the LGDT test could also be positive only when the posteromedial structures (sMCL, deep MCL, POL) and the cruciate ligaments (ACL and PCL) were all sectioned. In this cadaveric sequential sectioning study, the LGDT test showed positive merely at the following two situations: (1) the distal POP-T and PFL were both sectioned; (2) the posteromedial structures (sMCL, deep MCL and POL) and the cruciate ligaments (ACL and PCL) were all sectioned. Accuracy of the LGDT test in diagnosing acute or chronic posterolateral corner (PLC) injuries will improve with the information in this study. It was the combined POP-T and PFL injuries that finally led to a positive LGDT sign. However, one should be cautious to use the LGDT test in diagnosing the PLC injuries when posteromedial structures and cruciate ligaments were all involved.

Arthroscopic evaluation of persistent pain following supramalleolar osteotomy for varus ankle osteoarthritis.

The purposes of this study were to investigate pain experienced by patients after supramalleolar osteotomy for varus ankle osteoarthritis and to analyse correlations between this pain and arthroscopic findings. Twenty-nine patients (31 ankles) who underwent arthroscopic evaluation after supramalleolar osteotomy were reviewed retrospectively. The visual analog scale (VAS) was used to assess pain, and the patients were instructed to record the time point, location, and character of the pain. The tibial-ankle surface angle, talar tilt, and tibial-lateral surface angle were measured on radiographs. The location, time point, and character of the pain experienced by the patients changed after supramalleolar osteotomy. The mean VAS score was significantly improved after supramalleolar osteotomy at the time of the arthroscopic evaluation (P<0.001) and improved further after the arthroscopic procedures (P=0.026). During arthroscopy, pathologic lesions such as adhesions, synovitis, and soft-tissue impingement were identified. A significant correlation was found between adhesions and dull pain and pain at rest (P=0.016 and P=0.005, respectively). In addition, soft-tissue impingement in the lateral gutter was significantly correlated with dull pain, pain at rest, and clicking pain (P=0.001, P=0.035, and P=0.042, respectively). No significant correlations were found between post-operative radiographic measurements and development of pathologic lesions. With the use of arthroscopy, persistent pain experienced after supramalleolar osteotomy was found to be associated with adhesions, synovitis, and soft-tissue impingement in medial and lateral gutters of the ankle. Arthroscopy can be helpful in identifying and treating painful lesions commonly seen after supramalleolar osteotomy. An understanding of these painful lesions will help patients have more realistic expectations regarding the supramalleolar osteotomy. Case series study, Level IV.

Arthroscopic Identification of the Anterolateral Ligament of the Knee

Intense interest has focused on the recent description of the anterolateral ligament of the knee. Advancing knowledge of its anatomy and function is leading to a realization of its importance in the rotatory control of the tibia in anterior cruciate ligament injuries. Reconstruction of this structure will increasingly become an important goal during anterior cruciate ligament reconstruction. However, preoperative assessment of this ligament is difficult. Clinical assessment of rotatory laxity has poor reproducibility, and it is difficult to define using current imaging techniques. This article is the first to describe a safe and reproducible arthroscopic technique to allow identification and examination of the anterolateral ligament of the knee. With the knee at 90° of flexion, the arthroscope is introduced through the anterolateral portal to allow clear visualization of the lateral gutter. Under direct vision, an accessory portal is made over the inferior limit of the lateral gutter. A shaver is then introduced through this portal and used to debride this synovial recess and define the anterolateral ligament. This allows the surgeon to examine the integrity of the anterolateral ligament, in particular its femoral insertion. If required, this additional information can facilitate the performance of a more accurate and effective extra-articular reconstruction.

Lesser Metatarsal Phalangeal Joint Arthroscopy: Anatomic Description and Comparative Dissection

The aim of this article is to describe the normal arthroscopic anatomy of the lesser metatarsophalangeal (MTP) joints and compare it with that seen in open dissection in cadaveric models. We performed arthroscopic examination of 18 MTP joints of 6 normal fresh frozen feet. The second, third, and fourth MTP joints were studied because of the higher incidence of pathologic conditions found in these joints. During arthroscopy, each anatomic structure identified was named and marked with different colored sutures using straight suture needles. After the arthroscopic procedure of identification and marking, each MTP joint was dissected, and all the anatomic structures were grossly identified. With these data, the correlation between the arthroscopic and the direct visualization of a normal MTP joint was established. Considering the joint regions, we found that the examination accuracy of the medial gutter was 91%, whereas the central joint accuracy reached 100% and the accuracy of the lateral gutter was 98%. The overall arthroscopic accuracy for the lesser MTP joints was 96%. There is a high level of anatomic accuracy at the lesser MTP joint with arthroscopy. The high overall level of anatomic accuracy of lesser MTP joint arthroscopy (96%) allows us to consider this resource as a valuable tool in the diagnosis and treatment of these joints, expanding the spectrum of indications using this method.

Periarticular Injection Technique to Enhance Pain Relief After Knee Arthroplasty.

Currently, a popular form of pain control following total knee arthroplasty is the use of periarticular injections; how the medications are injected is a critical step in the efficacy of this modality. The setup includes the injection fluid and two control syringes with a 22-gauge needle. Inject around the femur before placing the implants. This is another area of rich innervation that needs to be injected carefully. Use a similar technique of slow small-volume injections, watching for the periosteal wheal or elevation off the bone. Include the lateral gutter and proximal extensor mechanism as well as around the patella, with minimal injection into the skin. Careful injection technique improves the outcome of periarticular injections for pain control. Indications ContraindicationsPitfalls & Challenges.

Arthroscopy-Assisted Closed Reduction and Percutaneous Nail Fixation of Unstable Ankle Fractures: Description of a Minimally Invasive Procedure

When one is surgically managing an unstable ankle fracture, anatomic reduction of the syndesmosis is typically accomplished using an open surgical approach. We propose an arthroscopically assisted technique that restores normal anatomy while using a percutaneously placed intramedullary nail to fix the fibula. The patient is positioned supine, and the ankle is placed under traction by use of a tensor bandage. Standard anteromedial and anterolateral arthroscopy portals are used. The joint is examined for bony, ligamentous, and chondral injury. Lateral malleolus fracture reduction is accomplished with pointed reduction forceps to apply traction and rotation to the tip of the distal fibula fragment. A retrograde fibular intramedullary nail (Acumed, Hillsboro, OR) is inserted under fluoroscopic guidance. Arthroscopy is then used to guide the reduction of the fibula and rotation of the fibula with placement of the arthroscope in the lateral gutter. Syndesmosis screws are placed once the fracture and syndesmosis reductions are confirmed through both fluoroscopy and arthroscopy.

Bone temperature elevation by drilling friction and neurological outcome in the cervical spino-laminoplasty

Drill-induced heat has been suspected as a cause of tissue injury, and there are ample experimental data to substantiate the implication. However, no clinical results have been presented with measurement of temperature in the vicinity of neural structures during the actual spinal procedures. Using a thermocouple, temperature in the gutters drilled in the midline and the lateral margins of the lamina was monitored closely in 61 patients, who underwent the French-door style of cervical spino-laminoplasty. The drilling was performed intermittently for a duration of 5 or 10 seconds, using 3- or 5-mm diamond burrs with sufficient continuous cooling irrigation. The correlations between bone temperature elevation and postoperative sensorimotor symptoms were then analyzed. In the lateral gutters at the most cephalad level (typically C3), where the drilling was performed underneath an overlying bundle of muscle attached to C2's spinous process, the temperature rose significantly. This occurred even with 5-second drilling sessions. The average peak temperature was 44 °C at this level. At all other sites, the temperature was maintained below 40 °C. In three patients, transient neurological deficit developed postoperatively, which did not correlate with the incidence of bone temperature elevation. Intermittent drilling with sufficient irrigation can prevent thermal neuronal damage generated by high-speed drills. Drilling with small diamond burrs in deep and narrow spaces covered by overlying muscles predisposes to inadequate irrigation and thermal elevation. Continuous, protracted drilling without frequent irrigation may result in excessive heat generation and nerve injury.

Tethering Technique for Revision of a Thoracic Spinal Cord Stimulator Paddle: A Case Report

Revision of a displaced permanent spinal cord stimulator paddle lead presents certain challenges, not least of which is how to maintain the implant in the correct position. The author recently encountered a patient whose thoracic lead, which was originally placed in the midline, migrated into the lateral gutter. As a fibrous sheath had already formed around the lead in the displaced position, simply moving it back to the midline was felt to have a low probability of success. The author was able to successfully reposition the implant and anchor it with a technique that was recently presented for use in the cervical spine ( 1. Amrani J. A novel technique for the implantation of paddle leads in the cervical spine. Neuromodulation 2013. DOI: 10.1111/ner.12022 Google Scholar ).

Validity of a Novel Arthroscopic Test to Diagnose Posterolateral Rotational Instability of the Knee Joint: The Lateral Gutter Drive-Through Test

The purpose of this study was to assess the validity of a newly developed arthroscopic test, termed the lateral gutter drive-through (LGDT) test, to diagnose posterolateral rotational instability (PLRI) of the knee joint. Between October 2009 and February 2012, 115 consecutive patients were enrolled into this prospective diagnostic study. The dial test was used as the gold standard for diagnostic reference. According to the dial test, the patients were divided into a study group (35 patients) and a control group (80 patients). The LGDT test was performed on all patients during arthroscopic surgery. The sensitivity and specificity of the LGDT test were calculated. Sensitivities were also calculated in subgroups defined by injury patterns and extents of tibial external rotational instability. The sensitivity and specificity of the LGDT test were calculated as 91.4% and 93.8%, respectively. In subgroup analyses the sensitivity of detection for acute PLRI was 90% versus 92% in chronic cases (P = .849). Popliteus femoral "peel-off" lesions were detected with a sensitivity of 100% versus 87.0% in cases of non-peel-off lesions (P = .536). The sensitivity of detecting isolated external rotational instability versus combined instability (rotational and varus) was 90.5% versus 92.8% (P = .805). The sensitivity of the LGDT test was correlated with the extent of tibial external rotational instability (P < .001). This study showed that the LGDT test is a reliable method and can be used for diagnosing PLRI of the knee joint. The highest sensitivity was observed in patients with the femoral peel-off injury pattern. The sensitivity of the LGDT test was correlated with the extent of tibial external rotational instability and was significantly higher in patients with an increase in tibial external rotation by more than 10°. Level I, diagnostic study: testing of previously developed criteria in a series of consecutive patients.

Neglected locked vertical patellar dislocation.

Patellar dislocations occurring about the vertical and horizontal axis are rare and irreducible. The neglected patellar dislocation is still rarer. We describe the clinical presentation and management of a case of neglected vertical patellar dislocation in a 6 year-old boy who sustained an external rotational strain with a laterally directed force to his knee. Initially the diagnosis was missed and 2 months later open reduction was done. The increased tension generated by the rotation of the lateral extensor retinaculum kept the patella locked in the lateral gutter even with the knee in full extension. Traumatic patellar dislocation with rotation around a vertical axis has been described earlier, but no such neglected case has been reported to the best of our knowledge.

Comparative Performance of Ankle Arthroscopy with and without Traction

Ankle arthroscopy has evolved as a diagnostic and therapeutic tool. Traditionally, it is performed with traction because of the tight ankle joint space. Original traction techniques were invasive but have progressed to the commonly used noninvasive modalities. Recent reports have suggested traction may be unnecessary. The purpose of this study was to compare prospectively ankle arthroscopy with and without traction in terms of ease of visualization of anatomic structures according to the Ferkel's ankle arthroscopy criteria. Under Institutional Review Board approval, 103 patients received ankle arthroscopies, first with noninvasive traction and subsequently without traction. An independent observer scored each arthroscopy based on the 21-point Ferkel's criteria. For each structure adequately visualized, one point was given. Inadequate visualization was defined as excessive force or as visible cartilage scuffing. The maximum possible score was 21 points and the lowest was zero. Fifty-five females and 48 males, average age 35 (range, 16 to 71) years, participated in the study. Noninvasive traction facilitated visualization of all structures of the anterior ankle in more than 90% of cases except for the anterior compartment and lateral gutters, which were better visualized without traction with the ankle in dorsiflexion. No difference was seen when visualizing the talus. Traction arthroscopy performed better when evaluating the central and posterior ankle. The mean score difference was statistically significant, 11.2 versus 18.5 points, favoring noninvasive traction arthroscopy. The complication rate was 4%. Noninvasive traction facilitated complete ankle arthroscopy. Dorsiflexion improved visualization of the anterior compartment and lateral ankle gutter. The authors recommend noninvasive traction when performing ankle arthroscopy.

Pigmented Villonodular Synovitis of the Ankle

Because of its high recurrence rate, complete excision with total synovectomy is crucial for diffuse pigmented villonodular synovitis (DPVNS). Regardless of location, surgical approach requires meticulous soft tissue management and full joint exposure to assure complete tumor excision. In the ankle, PVNS can be present in the medial and lateral gutters, as well as extend along the syndesmotic ligament, flexor and peroneal tendon sheaths, and adjacent joints (ie, subtalar and midtarsal joints). The authors describe an open, anterior-posterior technique for excision of DPVNS lesions from the ankle joint with erosive lesions of the tibia and talus, as well as from the flexor hallucis longus and peroneal tendon sheaths. Whereas previously described dual-incision techniques have focused on posteromedial and posterolateral approaches to the ankle, the authors' posterior exposure, in particular, uses a midline skin incision and a longitudinal split of the Achilles tendon. This provides an excellent exposure and minimizes potential wound healing complications.

Femoral Peel-Off Lesions in Acute Posterolateral Corner Injuries: Incidence, Classification, and Clinical Characteristics

The purpose of this study was to determine the incidence of acute avulsions of the popliteus tendon (PT) and lateral collateral ligament (LCL) of the femur (peel-off lesions) in knees with multiple injured ligaments. This study also describes the tear patterns and associations based on preoperative magnetic resonance imaging (MRI), physical examination, and arthroscopic inspection with injury patterns. This was a retrospective review of a consecutive series of 48 acute grade III posterolateral knee repairs and reconstructions. All office evaluations were reviewed to determine the preoperative MRI examination results, the findings on physical examination with the patient under anesthesia, and the intraoperative arthroscopic findings. In total, 19 patients (40%) were surgically verified as having peel-off lesions. Tears were typically categorized into 3 patterns: isolated PT tear (pattern 1) (4 of 19 [21%]), combined PT and LCL tears (pattern 2) (8 of 19 [42%]), and complex tears (associated intrasubstance- and/or fibula-based injuries) (pattern 3) (7 of 19 [37%]). Of the patients, 82% (14 of 17) showed conclusive MRI signs of femoral insertion separation and discontinuity. Examination with the patient under anesthesia showed tibial external rotation of greater than 10° in 84% of patients (16 of 19) and positive varus instability in 73% (11 of 15). Arthroscopic findings of acute avulsion and a positive lateral gutter drive-through sign were found in 94% (16 of 17). In a series of 48 grade III, consecutive, acute posterolateral corner surgery cases, we found that 19 patients (40%) had peel-off lesions. For adequate clinical identification, we recommend a comprehensive diagnostic protocol, including MRI, physical examination, and arthroscopic inspection, to avoid underdiagnosis of the lesion in multiple ligament-injured knees. The lateral gutter arthroscopic evaluation is particularly sensitive for detecting the lesion. Level IV, therapeutic case series.

Arthroscopic Arthrolysis for Arthrofibrosis of the Knee after Total Knee Replacement

Arthrofibrosis is an uncommon but potentially debilitating complication following total knee replacement which can result in chronic pain and poor recovery of range of motion. The treatment of this condition remains difficult and controversial. QUESTIONS/AIMS OF STUDY: We reviewed our results of arthroscopic arthrolysis of arthrofibrosis of the knee after total knee replacement to assess the potential for this technique to improve range of motion and provide improvement in knee function and pain as measured by the Knee Society Score (KSS). Eight patients were treated for arthrofibrosis after total knee replacement with arthroscopic management. The patients included five females and three males. The average age was 67.4years. Initial rehabilitation efforts, which included manipulation under anesthesia, had failed. Arthroscopic arthrolysis was performed to release fibrous bands in the suprapatellar pouch and to reestablish the medial and lateral gutters. Lateral release of the patellar retinaculum was performed. Intensive physiotherapy and continuous passive motion began immediately post-operatively. The average follow-up was 37.4months. The KSS was used for assessment of pain and function before arthroscopy and at the latest follow-up. Six of the eight patients experienced improvement in the KSS. The average functional score showed improvement from 68 points pre-operatively to 86 at the time of final follow-up. The average pain scores improved from 30 points pre-operatively to 41 at the time of final follow-up. Arthroscopic management can be beneficial for patients suffering from arthrofibrosis following total knee replacement. Pain and KSS clinical scores can markedly improve.

Clinical study of femoral peel-off lesions in acute posterolateral corner injuries

Objective To determine the incidence of clinically common acute avulsions of the popliteus tendon (PT) and the lateral collateral ligament (LCL) of the femur (peel-off lesion) in knees with multiple injured ligaments.Methods A retrospective review of 48 acute grade 3 posterolateral corner (PLC) knee surgeries was conducted.All office evaluations were reviewed to determine the demographic data,tear description,preoperative MRI examination,physical examination under anesthesia,intraoperative arthroscopic findings and surgical techniques.Results In total,19 patients were surgically verified as having femoral peel-off lesions as a portion of a series of multiple pathologic findings.Tear patterns were typically categorized into 3 patterns:isolated PT tear (pattern 1,4 patients),combined PT and LCL tears (pattern 2,8 patients) and complex tears (associated intrasubstance and/or fibular-based injuries,pattern 3,7 patients).Seventeen of the 19 patients underwent preoperative MRI examination,which demonstrated conclusive signs of femoral insertion separation and discontinuity in 13 patients (76%) and inconclusive signs of femoral insertion separation.Examination under anesthesia (EUA) revealed that for the 4 patients with pattern 1 injuries,the tibial external rotation increases were all greater than 10°.For the 15 patients with pattern 2 and 3 injuries,the yarus instability was as follows:grade 3 in 8 patients,grade 2 in 2,grade 1 in 1,and negative in 4.External rotation increases were greater than 10° in 12 patients and less than 10° in 3.Seventeen of the 19 patients were inspected with an arthroscope prior to PLC surgery:of these patients,94% had acute avulsion findings and positive lateral gutter drive-through sign;8 patients were repaired with recess or reattachment procedures;6 patients were primarily reconstructed;4 patients were treated with combined repair and reconstruction;and 1 patient was left untreated for secondary reconstruction due to priority repair for concurrent patellar tendon rupture.Conclusion For adequate clinical identification,we recommend a comprehensive diagnostic protocol,including MRI,physical examination and arthroscopic inspection,to avoid underdiagnosis of the lesion in multiple-ligament injured knees.The lateral gutter arthroscopic evaluation is particularly sensitive for detecting the lesion. Key words: Arthroscopy; Knee injuries; Ligaments; Treatment outcome