Meniscal Injuries of the Knee Learning Objectives Edward P. Mulligan, MS, PT, SCS, ATC VP, National Director of Clinical Education HealthSouth Corporation Grapevine, TX Clinical Instructor University of Texas Southwestern PT Dept Dallas, TX The contents of this presentation are copyrighted 2004 by. They may not be utilied, reproduced, stored, or transmitted in any form or by any means, electronic or mechanical, or by any information storage or retrieval system, without permission in writing from Edward P. Mulligan. Following the completion of the inservice the participant will be able to: 1. identify meniscal anatomy and vascular penetration 2. describe meniscal biomechanics, pathomechanics, and mechanisms of injury 3. explain common meniscal mechanisms and resultant classification of injury 4. describe relevant orthopedic examination procedures relevant to the meniscus 5. define indications for surgical excision, repair, and allograft replacement 6. design and effective post-operative rehab program Meniscal Anatomy Semilunar wedges of fibrocartilage interposed between the femoral condyles and tibial plateau Medial Meniscus "C" shaped Broader posteriorly than anteriorly Peripheral Attachments: entire peripheral border is firmly attached to the medial capsule semimembranosus tendon slip attaches to posterior horn fibers of ACL attach to anterior horn meniscopatellar fibers attach to medial border of meniscus ED Lateral Meniscus Chock Block Shape "O" shaped covering 2/3 of tibial plateau Smaller in diameter, thicker in periphery, and wider in body than the medial meniscus More mobile than medial meniscus Peripheral Attachments: popliteus muscle (not tendon) sends fibrous slip to posterior border ligament of Wrisberg (meniscofemoral ligament) attaches to posterior horn anterior horn to ACL Frontal and sagittal x-sections show the triangular wedge shape (thick on periphery and thin centrally)
Meniscal Vascularity Meniscal Vascularity Blood supply comes from the genicular arteries with vascular penetration to the peripheral 10-30% Vascular Zones Red Zone - peripheral capsular attachment area; outer 3 mm rim Pink Zone -junction of vascular and avascular one; blood supply on periphery, but not centrally Avascular Zone - inner 2/3 of meniscus without blood supply Meniscal Function Meniscal Function Joint Stability Small but significant role in resisting varus, valgus, rotational, and AP stresses If ACL intact, menisectomy does not significantly increase AP laxity If ACL deficient, menisci play a more important role in stability After menisectomy there is a significant increase (3 mm) in AP laxity Removal of posterior horn of medial meniscus alone will destabilie the meniscus Shock Absorption and Load Transmission Menisci the tibiofemoral contact area by 75% Loss of menisci results in smaller areas of tibiofemoral contact Partial menisectomies peak local contact stress by 65%; total menisectomy by 235% Menisci transfer centrally applied stresses radially Loss of menisci function through menisectomy or radial tear will result in increased load transfer to articular cartilage and subchondral bone Meniscal Function Meniscal Passive Biomechanics Nutrition and Joint Lubrication The menisci help distribute a thin film of synovial fluid over the surface of the articular cartilage Femoral condyles displace menisci as a result of compression and translation the conjoint internal rotation of the tibia during flexion occurs about an axis medial to the knee joint menisci move posterior with flexion and anterior with extension medial meniscus moves about 6 mm and the lateral meniscus about 12 mm Joint Congruency Tapered ring geometry promotes the mating of two incongruent surfaces
Part 2: Meniscal Active Biomechanics Flexion Mechanisms, Classification, and Examination Extension Medial Meniscus - posterior glide is assisted by semimembranosus and counteracted by the pull of the meniscopatellar fibers and the ACL which attach to the anterior horn Lateral Meniscus - posterior glide is assisted by the fibers of the popliteus Medial Meniscus -assisted by meniscopatellar fibers and influenced by the active contraction of the quads Lateral Meniscus - posterior horn is pulled anteriorly by the increased tension on the meniscofemoral ligaments from the PCL Tibial Rotation SMB POP influenced by meniscopatellar fiber tension and the larger articulating femoral condyle Meniscal Tears: Mechanism of Injury Meniscal Tears: Mechanism of Injury Elderly Degeneration Youthful Trauma Rotational and Compressive forces with the knee partially flexed Non-specific trauma with slow, insidious onset 60% likelihood of degenerative tear after 60 menisci degenerate as they become less pliable and complex or radial tearing is generally irreparable menisci are torn (usually longitudinal tears) when they are caught, pinched, or impaled between the condyles Meniscal Injury Predisposing Factors Abnormal mechanical axes discoid lateral meniscus Congenital anomalies genu varus/valgus Discoid menisci Degenerative menisci Ligamentous laxity Meniscal Injury Incidence Medial meniscus is torn 5-7 times more often than lateral meniscus Medial meniscus is injured more often because it is far less mobile The least mobile portion of the menisci is the medial posterior horn Posterior horn tears most common medially and transverse tears most common laterally The medial meniscus is most commonly injured in the stable knee or in the chronic ACL deficient knee The lateral meniscus is most commonly injured with an acute ACL tear. 3
Meniscal Injury Classifications Shape Complete vs. Incomplete Stable vs. Unstable Peripheral vs. Central Red - blood supply on both sides Good potential to heal Pink - blood supply on periphery, but not centrally - within the avascular one Poor potential to heal Meniscal Injury Clinical Features subjective factors to differentiate meniscal and patellar pathology History Trauma - twisting injury Degenerative - no history of specific injury; often in middle age Mechanical Symptoms locking, catching, clicking, snapping, giving way Swelling and Pain Physical Exam 1. Joint line tenderness 2. Effusion 3. + McMurray's, Apley's, Squat Test 4. Quad Shutdown or atrophy MENISCAL Twisting, traumatic onset Joint line symptoms Locking Sharp pain with loaded cutting maneuvers PATELLOFEMORAL Gradual, insidious onset Diffuse, anterior symptoms Grating, Aching, Crepitation Pain coming into or out of squat Objective Exam: Special Tests Meniscal Entrapment Testing Specific combinations of motion to identify symptomatic meniscal injury Flexion to extension with tibia: externally rotated and valgus stress internally rotated and valgus stress externally rotated and varus stress internally rotated and varus stress As you move through the range of motion, note where and when the patient notes pain or catching-clicking sensations.
meniscal entrapment test Rationale Flexion compresses the posterior portion of the menisci. Catching or locking in flexed positions indicates damage to the posterior meniscal elements. Extension compresses the anterior portion of the menisci. Catching or locking in extended positions indicates damage to the anterior meniscal elements. Tibial Rotation used to distort the menisci & assist in identifying the area of the meniscal lesion meniscal entrapment test Rationale Varus Stress compresses the medial compartment to increase catching, clicking, or locking symptoms may cause stretch pain of meniscal attachments on the lateral side of the joint Valgus Stress compresses the lateral compartment to increase catching, clicking, or locking symptoms may cause stretch pain of meniscal attachments on medial side of the joint meniscal entrapment test Interpretation what portion of the menisci is under stress? Meniscal tears/lesions do not hurt (they are aneural) - they click, catch, or lock The pain produced from the entrapment tests occurs at the site of meniscal tissue attachments. Pain is located over the specific area of pathology with palpation but may be reported in the opposite corner of the actual pathology during the entrapment tests with these specific entrapment test methods posteromedial posterolateral McMurray Test Medial Meniscal Testing Extension from a hyperflexed position in varus and internal rotation = posteromedial meniscal injury McMurray Test Lateral Meniscal Testing Extension from a hyperflexed position in valgus - external rotation = posterolateral meniscal injury
Apley s Compression - Distraction Test meniscal testing truth Apley s Compression Test Hard downward pressure is applied with rotation Pain indicates a meniscal injury Apley s Distraction Test Traction is applied with rotation Pain will occur if there is damage to the capsule or ligaments No pain will occur if it is meniscal TEST Citation Sensitivity Specificity MRI Jackson 93% 90% McMurray Evans 20% 91% McMurray Fowler 29% 96% Apley (compression) Fowler 16% 80% Joint Line Tenderness Fowler 85% 30% Pain on Forced Flexion Fowler 51% 70% Block to Extension Fowler 44% 86% Sensitivity - % patients correctly identified by the test - good at ruling out Specificity - % patients correctly not identified by the test - good at ruling in MRIs are about 90% accurate Operative vs. Conservative Management Small, peripheral, stable tears that are not causing functional limitations may respond to non-surgical intervention uniform black signal at the tip of red arrow white signal within black signal at the tip of the red arrow Part 3: Surgical Considerations Meniscal Surgical Options Partial Menisectomy Meniscal Repair Meniscal Allograft
Meniscal Surgical Indications Meniscal Repair Techniques Partial Menisectomies complex tears in avascular one Large flap or radial tears degenerative tears irreparable tears Meniscal Repair young patients - all tears except inner 4-6 mm stable knees complete longitudinal tears greater than 1 cm in length High % of success Seems to be independent of age, length of tear, or time since injury 90% success in ACL reconstructions; 30-40% failure in ACL deficient knees Meniscal Repair Techniques Outside-In Meniscal Repair Sutures Inside Out: middle and posterior tears Outside In: anterior tears Arrows All inside barbs, harpoons, darts Inside-Out Meniscal Repair All Inside Meniscal Arrow Repair Meniscal arrows or darts are tiny biodegradable polymer harpoons that hold together the torn portions of a meniscal tear until the fragments join together and the arrow dissolves.
Meniscal Healing Prognosis Part 3: Post-Operative Rehabilitation GOOD PROGNOSIS Younger Patient (under 35) Peripheral Damage Longitudinal Tear Short Tear Acute Injury (bloody effusion) Stable Knee POOR PROGNOSIS Older Patient Central Damage Complete Tear Bucket Handle Tear Chronic Injury Unstable Knee Pro-Active Post-Arthroscopic Knee Rehab Pro-Active Post-Arthroscopic Knee Rehab BOTH the surgical procedure and subsequent clinical rehabilitation influences the rate and extent of recovery Hughston, 1980 The earlier AROM is allowed, the earlier full ROM is achieved Sherman, 1983 Patients need post-operative physical therapy to normalie motor control, muscular strength, and gait Durand, 1991 and 1993 Supervised rehab facilitates successful outcomes Moffett, APMR, 1994 Timm, 1988 retrospective study on 5,000+ post-op knee cases POST-OPERATIVE CARE SUCCESS RATE No exercise 0% Home exercise instruction only 9% Supervised isotonic exercise program 48% Supervised isokinetic and comprehensive rehab 92% Physical Therapy Efficacy Physical Therapy Efficacy No differences between home program and HEP with six weeks of supervised physical therapy according to a variety of outcome measures Outcomes questionnaires Days return to work Gait kinematics Hop/Jump tests Vervest AM, et al. Effectiveness of physiotherapy after menisectomy. Knee Surg Sports Traumatol Arthrosc. 1999; 7(6):360-364 Physiotherapy group showed significantly better results than the control group in regards to patient satisfaction and functional outcomes Goodwin PC et al, Phys Ther 83:520-535, 2003
post-op meniscal rehab considerations post-op menisectomy rehabilitation considerations Proactive approach Protected arcs of motion Varus-valgus stress Rotational torque OKC vs. CKC Time to Return Excisions: 4-6 weeks Repairs: 4-6 months Control post-op pain/swelling FWB when gait normalies ROM and strengthening to tolerance Return to activity typically takes 3-6 weeks post-op meniscal repair rehab considerations post-op meniscal repair rehab considerations General Considerations and Influences Site of repair Red vs. white Complex vs. peripheral Associated pathologies General Considerations and Influences Age Athletic or ADL goals Surgeon Philosophy post-op meniscal repair rehab considerations Post-operative Rehab Protocol Immediate protected motion post-op (0-90 for 4 wks) Locked in full extension if early weight bearing; FWB at 4-6 wks Neoprene compression sleeve to minimie swelling and provide support Slow, gradual progressions based on objective status No resistive flexion for 2 months No squats or twisting activities for 3-6 months 4-6 month restriction on return to athletics www.continuing-ed.cc Need acrobat reader software to download and print. Free link is also at web site
Remember a good clinician knows when to ignore the protocol s suggestions meniscal allograft rehabilitation Locked in full extension first 6-8 weeks Progressive weight bearing over 6-12 weeks Slow gradual progression 6-12 months to return to full, unrestricted activity Frit JM, Irrgang JJ, Harner CD. Rehabilitation following allograft meniscal transplantation: a review of the literature and case study. J Orthop Sports Phys Ther. 1996 Aug; 24(2): 98-106. References