Courtesy: CMC Ortho Residency

ACL, PCL and Meniscus Injuries: High-Yield Sports Medicine Review

Introduction

Injuries involving the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and meniscus are among the most common conditions encountered in sports medicine and knee surgery.

These structures play a vital role in:

Knee stability
Load transmission
Rotational control
Shock absorption

Understanding their anatomy, biomechanics, clinical presentation, and management principles is essential for accurate diagnosis and effective treatment.

Anterior Cruciate Ligament (ACL)

Anatomy and Function

The ACL is the primary stabilizer preventing:

Anterior translation of the tibia

Secondary functions include:

Controlling internal rotation
Providing varus and valgus stability

ACL Bundles

The ACL consists of two functional bundles.

Anteromedial (AM) Bundle

Tight in knee flexion
Main restraint during the Lachman test
Primary stabilizer against anterior tibial translation

Posterolateral (PL) Bundle

Tight in knee extension
Responsible for rotational stability
Important in the pivot shift phenomenon

Blood Supply

The ACL receives blood supply primarily from the:

Middle genicular artery

Secondary Stabilizers of the ACL

Important secondary stabilizers include:

Posterior horn of the medial meniscus
Posterolateral corner (PLC)

Ramp Lesion

A ramp lesion refers to:

Meniscocapsular separation of the posterior horn of the medial meniscus

Important points:

Frequently missed on MRI
Best visualized through a posteromedial arthroscopic portal

Mechanism of Injury

ACL injuries commonly occur due to:

Non-contact pivoting injuries
Twisting combined with valgus stress

Clinical Presentation

Typical features include:

Audible “pop”
Rapid hemarthrosis
Instability
Difficulty continuing sports activity
Quadriceps avoidance gait

Associated Injuries

Acute ACL Injury

More commonly associated with:

Lateral meniscus tears

Chronic ACL Deficiency

More commonly associated with:

Medial meniscus tears

Risk Factors

ACL injuries are particularly common in female athletes because of:

Increased valgus landing forces
Narrow intercondylar notch
Generalized ligament laxity
Neuromuscular imbalance

Neuromuscular imbalance is considered the most important modifiable factor.

Clinical Examination

Lachman Test

Most sensitive and specific clinical test for ACL injury

Anterior Drawer Test

Less reliable than Lachman testing

Pivot Shift Test

Most specific test for rotational instability

Mechanism:

Tibia subluxes anteriorly in extension
Reduces with a clunk during flexion at 20–30°

MRI Findings

A characteristic pivot-shift bone bruise pattern includes:

Central lateral femoral condyle
Posterior lateral tibial plateau

Management

Non-Operative Treatment

Appropriate for:

Low-demand patients
Elderly individuals
Arthritic knees

Treatment includes:

Physiotherapy
Strengthening
Activity modification

Surgical Management

ACL reconstruction is indicated in:

Young active patients
Functional instability
Athletes desiring return to pivoting sports

Graft Options

Autografts

Common autografts include:

Bone-patellar tendon-bone (BTB)
Hamstring tendon
Quadriceps tendon

Allografts

Advantages:

Avoid donor-site morbidity

Disadvantages:

Higher failure rate in young patients
Delayed incorporation
Rare risk of disease transmission

Graft Healing Phases

The graft undergoes four biological stages:

Necrosis
Revascularization
Cellular repopulation
Remodeling

Complications of ACL Reconstruction

Tunnel Malposition

Most common technical complication.

Anterior Tunnel Placement

Causes loss of flexion

Posterior Tunnel Placement

Causes loss of extension

Vertical Graft Placement

Leads to persistent rotational instability
Positive pivot shift

Cyclops Lesion

A cyclops lesion is:

Fibrous nodule formation in the intercondylar notch

Clinical feature:

Loss of terminal extension

Other Complications

Arthrofibrosis
Patellar fracture (BTB graft)
Residual instability

Rehabilitation

Preferred rehabilitation principles include:

Early motion
Closed-chain exercises
Avoidance of early open-chain quadriceps loading

Prevention

Neuromuscular training programs are effective in reducing ACL injury risk.

Routine bracing has limited effectiveness except possibly in:

Skiing athletes

Posterior Cruciate Ligament (PCL)

Anatomy and Function

The PCL is the primary restraint to:

Posterior translation of the tibia

Anatomy

Origin

Medial femoral condyle

Insertion

Posterior tibial sulcus

Functional Bundles

Anterolateral Bundle

Tight in flexion

Posteromedial Bundle

Tight in extension

Blood Supply

The PCL is supplied by the:

Middle genicular artery

Mechanism of Injury

The classic mechanism is:

Dashboard injury during motor vehicle accidents

Other causes include:

Fall onto a flexed knee
Hyperflexion injury
Hyperextension injury

Clinical Presentation

Acute Injury

Pain
Swelling

Chronic Injury

Difficulty descending stairs
Patellofemoral pain
Functional instability

Clinical Examination

Posterior Drawer Test

Gold standard examination test

Posterior Sag Sign

Posterior displacement of the tibia when knee is flexed

Quadriceps Active Test

Anterior tibial translation during quadriceps contraction

Important Clinical Concept

PCL injuries are frequently associated with:

Multi-ligament knee injuries
Posterolateral corner injuries

Management

Non-Operative Treatment

Preferred for isolated PCL injuries.

Main components:

Quadriceps strengthening
Bracing in extension

Surgical Indications

Surgery is indicated for:

Bony avulsion injuries
Combined ligament injuries
Persistent instability

Rehabilitation Principles

Avoid early hamstring activation
Emphasize quadriceps strengthening
Early prone range-of-motion exercises

Complications

Potential complications include:

Residual laxity
Neurovascular injury
Popliteal artery injury
Progressive medial and patellofemoral arthritis

Meniscus

Anatomy

Medial Meniscus

C-shaped
Less mobile
More commonly injured

Lateral Meniscus

More circular
More mobile

Attachments

The medial meniscus is attached to:

Medial collateral ligament (MCL)
Joint capsule

The lateral meniscus lacks LCL attachment and is stabilized by:

Popliteomeniscal fascicles
Meniscofemoral ligaments (Humphrey and Wrisberg)

Functions

The meniscus plays a major role in:

Load transmission
Shock absorption
Joint lubrication
Stability

Load transmission:

Approximately 50% in extension
Approximately 85% in flexion

Biomechanics

The meniscus converts:

Axial load into hoop stress

It is composed predominantly of:

Type I collagen

Blood Supply Zones

Red-Red Zone

Peripheral vascular region
Best healing potential

Red-White Zone

Intermediate healing capacity

White-White Zone

Avascular central zone
Poor healing potential

Clinical Examination

Joint Line Tenderness

Highly sensitive

McMurray Test

More specific

Apley Test

Less commonly used

Types of Meniscal Tears

Common tear patterns include:

Longitudinal tears
Bucket-handle tears
Radial tears
Horizontal cleavage tears

Longitudinal tears have the best healing potential for repair.

Association with ACL Injuries

Acute ACL injuries commonly involve lateral meniscus tears
Chronic ACL deficiency commonly causes medial meniscus tears

Management

Meniscal Repair

Repair is preferred whenever possible.

Indications include:

Peripheral tears
Red-red or red-white zone tears
Young patients
Acute tears
Associated ACL reconstruction

Meniscectomy

Indications include:

Degenerative tears
Complex irreparable tears
White-white zone tears

Meniscal Repair Techniques

Inside-Out Repair

Considered the gold standard

Outside-In Repair

Useful for anterior horn tears

All-Inside Repair

Common modern technique
Comparable outcomes to inside-out repair

Healing Process

Meniscal healing occurs through:

Fibrin clot formation
Vascular ingrowth
Fibrochondrocyte proliferation
Remodeling

Complications of Meniscal Surgery

Medial Repair

Risk to saphenous nerve

Lateral Repair

Risk to common peroneal nerve

Other complications include:

Arthrofibrosis
Re-tear

Consequences of Meniscus Loss

Meniscectomy significantly alters knee biomechanics.

Effects include:

Approximately 50% reduction in contact area
Increased contact pressure
Early osteoarthritis

Meniscus Transplantation

Indications

Young patients
Persistent post-meniscectomy pain
Minimal arthritis

Limitation

Meniscal transplantation does not reliably prevent:

Osteoarthritis progression

Special Conditions

Meniscal Cyst

Lateral meniscal cysts are commonly associated with horizontal tears
Medial cysts may resemble Baker’s cysts

Discoid Meniscus

A discoid meniscus is diagnosed on MRI using the:

“Bow-tie sign” on three or more consecutive slices

Treatment is indicated only if symptomatic and usually involves:

Saucerization
Repair if required

Final Take-Home Message

ACL, PCL, and meniscal injuries are fundamental topics in sports medicine and knee surgery.

Important principles include:

Accurate clinical examination
Understanding associated injuries
Appropriate use of MRI
Preservation of meniscal tissue whenever possible
Anatomical ligament reconstruction
Structured rehabilitation

Early diagnosis and evidence-based management are essential to restore knee stability, preserve joint function, and reduce long-term degenerative changes.

Post Views: 9,007