Meniscus surgery is one of the most common orthopedic procedures performed worldwide¹. Additionally, studies show that anterior cruciate ligament (ACL) injuries are accompanied by concomitant meniscus injuries in 48.5–62.7% of cases². Over the past decade, anterior cruciate ligament reconstruction (ACLR) surgeries have become increasingly prevalent. In Alberta alone, ACLR rates increased by 168% between 2002/03 and 2018/19¹, making these procedures a crucial consideration for clinicians treating patients post-operatively.
Not all meniscal tears are created equal—tear type impacts the need for surgery, surgical technique, recovery timeline, early post-operative restrictions, and return-to-sport progression. This article will explore the anatomy, tear types, and rehabilitation considerations for both isolated meniscal injuries and meniscal repairs performed alongside ACLR.
The primary functions of the meniscus include improving joint congruity, distributing load, and absorbing shock. Recently, there has been a shift toward preserving the meniscus when possible, especially in conjunction with ACL injuries². The medial and lateral menisci conform to the curvature of the femur, increasing tibiofemoral contact area and reducing joint translation—including anterior translation, which is protective of the ACL post-operatively.
Meniscus Anatomy and Function
The meniscus is divided into three zones based on vascular supply: Red-Red (outer), Red-White (middle), and White-White (inner). The Red-Red zone has the most blood supply and therefore the greatest potential for healing. Type I collagen predominates in the Red-Red zone, while Type II collagen is more prevalent in the White-White zone. Collagen fibers are arranged in a three-layer structure².
The deep layer contains Type I collagen fibers aligned circumferentially to absorb tibiofemoral load by distributing it throughout the meniscus. This helps avoid point loading (high pressure applied over a focal point within the knee joint) and is termed the hoop stress mechanism². The middle layer features woven Type I collagen fibers that tie the deep fibers together, increasing rigidity and resistance to splitting².
Meniscus repair is often prioritized by surgeons to maintain joint stability, proprioception, and load distribution, and should be factored into rehabilitation planning—whether in isolation or combined with ACLR.
Meniscal Tear Types and Key Considerations
Vertical longitudinal tears run parallel to the circumferential collagen fibers and perpendicular to the tibial plateau. These are often traumatic in origin. In isolated injuries, they are more common in the medial meniscus, while in ACL injuries they frequently appear in the lateral meniscus. Because they follow the natural fiber orientation, they often remain stable and do not significantly disrupt joint biomechanics—unless displaced, forming “bucket handle” tears. These tears, even when asymptomatic, are typically repaired when feasible due to their favorable position for suture fixation.
Radial tears originate from the inner (avascular) portion of the meniscus and extend outward toward the periphery. These tears are perpendicular to the circumferential fibers and thus significantly disrupt the meniscus’s ability to convert tibiofemoral load into hoop stress³. Root tears—radial tears near the posterior meniscal insertion—are particularly concerning. They reduce contact area and increase peak contact pressures to levels similar to those seen after total meniscectomy. Even small deviations (3mm) from anatomical repair sites can severely limit function. These tears often require surgical repair but have a low healing potential unless they reach the vascular zone. Meniscectomy is generally discouraged due to the loss of load-distribution capacity, especially in younger or active individuals³.
Horizontal tears run parallel to the tibial plateau, splitting the meniscus into upper and lower portions. These are often degenerative, developing over time due to shear stress rather than an acute incident. They may significantly increase joint contact pressure (up to 70%), especially if left untreated. Surgical repair has been shown to restore near-normal biomechanics (within 15% of baseline pressures)³.
Complex or degenerative tears involve multiple tear patterns or occur in non-classifiable configurations. These may or may not be linked to trauma and often occur with underlying joint degeneration. Healing potential is low, and repair is often not feasible. In some cases, partial meniscectomy may be the only option, especially in older, less active populations.
Early-Stage Rehabilitation Considerations
Weightbearing
Post-operative weightbearing protocols vary based on tear type and surgical approach. In isolated meniscus repairs, vertical tears (especially in the Red-Red zone) may be allowed immediate weightbearing as tolerated, while root or complex radial tears often require bracing and restricted weightbearing for 4–6 weeks⁴. In contrast, for ACLR with meniscus repair, surgeons may opt for accelerated protocols when dealing with simple tears, especially in younger or athletic populations. Always verify the surgical report for specifics on weightbearing status.
Proprioception
The meniscus, especially the lateral meniscus, is highly innervated with proprioceptive fibers². Isolated tears, particularly in the lateral meniscus, can impair balance and neuromuscular control. Studies show that individuals with meniscus injuries underperform in balance and perturbation tasks². Clinicians should implement proprioceptive training early in both isolated and ACLR+meniscus cases, continuing throughout all rehab stages.
Range of Motion (ROM)
For isolated meniscus repairs, ROM is often restricted to 90° of flexion for the first 2–6 weeks depending on tear location and surgical fixation³. ACLR+meniscus repairs may follow similar timelines, though some accelerated protocols allow earlier ROM initiation⁴. Research supports early ROM to limit edema, avoid AMI, and reduce muscle wasting. For both scenarios, communication with the surgical team is essential to tailor ROM progression appropriately.
Mid- and Late-Stage Rehabilitation Considerations
Criteria-Based Progression
There is limited high-quality evidence on return-to-sport (RTS) timelines following isolated meniscus repairs⁵. Historically, time-based milestones (e.g., RTS at 4–6 months) have been used, but this is shifting toward criteria-based decision-making—especially in athletic populations. For ACLR+meniscus, RTS success is not dependent on timing alone. One study showed that athletes who met RTS criteria had similar outcomes regardless of whether they returned before or after 9 months⁶.
For isolated meniscus injuries, RTS should be delayed until patients demonstrate:
Common Milestones for Recovery
- Full, pain-free ROM
- Normalized gait and movement quality
- Quadriceps and hamstring strength >90% limb symmetry index
- Satisfactory hop test performance and dynamic balance
- Can tolerate the demads of the sport/activity they are returning to
Functional testing and patient-reported outcome measures are critical tools for both isolated and combined injuries. In youth, studies suggest similar return-to-sport outcomes with or without meniscus repair⁷, reinforcing the importance of individualized progression over generalized timelines.
Summary
Whether in isolation or alongside ACL reconstruction, meniscal injuries demand structured, evidence-informed rehabilitation. Patients failing to restore weightbearing tolerance, ROM, and muscle activation in early rehab stages are at higher risk for complications such as arthrofibrosis, cyclops lesions, and persistent strength deficits⁸.
For isolated meniscus repairs, early priorities include edema control, protected loading, and initiation of ROM. These patients often progress faster than ACLR counterparts, but their outcomes are still contingent on meeting strength and function benchmarks.
For ACLR+meniscus repairs, clinicians must balance protection with early mobility. Normal ROM and gait should be restored within 6 weeks, even with conservative protocols. Return-to-sport should not be time-based alone, but guided by objective criteria, psychological readiness, PROMs, and cardiovascular preparedness.
Ultimately, rehabilitation must be individualized, respecting surgical details, tissue healing timelines, patient goals, and current best evidence.
References
- Paudel, Yuba Raj, Mark Sommerfeldt, and Don Voaklander. Increasing incidence of anterior cruciate ligament reconstruction: a 17-year population-based study. Knee Surgery, Sports Traumatology, Arthroscopy, 2023; 31(1): 248–255.
- Adams, Bryan G., Megan N. Houston, and Kenneth L. Cameron. The epidemiology of meniscus injury. Sports Medicine and Arthroscopy Review, 2021; 29(3): e24–e33.
- Markes, Alexander R., Jonathan D. Hodax, and Chunbong Benjamin Ma. Meniscus form and function. Clinics in Sports Medicine, 2020; 39(1): 1–12.
- Lind, Martin, et al. Free rehabilitation is safe after isolated meniscus repair: a prospective randomized trial comparing free with restricted rehabilitation regimens. American Journal of Sports Medicine, 2013; 41(12): 2753–2758.
- Fried, Jordan W., et al. Return-to-play and rehabilitation protocols following isolated meniscal repair—a systematic review. Arthroscopy, Sports Medicine, and Rehabilitation, 2021; 3(1): e241–e247.
- Kotsifaki, Roula, et al. Is 9 months the sweet spot for male athletes to return to sport after anterior cruciate ligament reconstruction? British Journal of Sports Medicine, 2025.
- Lehoczky, Győző, et al. Similar Return-to-Sports After Anterior Cruciate Ligament Reconstruction With or Without Meniscal Repair in Skeletally Immature Patients: A Prospective, Comparative Cohort Study. Journal of Pediatric Orthopaedics, 2025.
- Buckthorpe, Matthew, et al. Optimising the early-stage rehabilitation process post-ACL reconstruction. Sports Medicine, 2024; 54(1): 49–72.