What is the likely cause of swelling and protrusion on the anterior horn repair site that resolves with cessation of leg press or exercise in a patient with no mechanical symptoms, knee pain, or other complications?

Transient Exercise-Induced Meniscal Repair Site Swelling

The swelling and protrusion at the anterior horn repair site that resolves completely with rest and causes no pain or mechanical symptoms represents a benign, transient phenomenon related to normal physiologic stress on the healing meniscal tissue during loaded knee flexion, and does not require intervention beyond activity modification during the healing phase.

Understanding the Mechanism

This presentation is consistent with normal healing tissue response to mechanical loading rather than a pathological process:

• Meniscal repairs undergo dynamic stress during knee flexion and loading, particularly during exercises like leg press that combine axial compression with knee flexion 1
• The absence of mechanical symptoms (locking, catching) and pain indicates the repair remains structurally intact and is not experiencing gapping or failure 1
• Complete resolution with cessation of exercise confirms this is a reversible physiologic response rather than structural damage or progressive pathology 2, 3

Key Differentiating Features

Your clinical presentation excludes concerning pathology:

• No pain during regular daily activities rules out inflammatory processes, infection, or significant structural compromise 2, 3
• No mechanical symptoms excludes meniscal tear extension, loose bodies, or repair failure that would cause locking or catching 4
• Complete normalization after rest distinguishes this from progressive osteolysis, synovitis, or other pathological processes that would persist 4

Clinical Implications and Management

This represents expected healing tissue behavior under load and requires only conservative management:

• Continue with graduated rehabilitation but temporarily reduce loading intensity during exercises that reproduce the swelling, as excessive stress on healing meniscal tissue can affect healing rates 1
• The repair site experiences increased mechanical stress during loaded knee flexion, which can cause transient fluid accumulation or tissue edema in healing structures without indicating failure 1
• Monitor for development of pain, persistent swelling, or mechanical symptoms which would indicate progression requiring further evaluation 2, 3

When to Escalate Care

Imaging or surgical consultation would only be warranted if:

• Pain develops during regular activities or at rest, suggesting inflammatory or structural complications 4, 2
• Mechanical symptoms emerge (locking, catching, giving way), indicating possible repair failure or meniscal displacement 4
• Swelling becomes persistent and no longer resolves with rest, suggesting synovitis, infection, or other pathological process 4
• Functional decline occurs with inability to perform previously tolerated activities 2, 3

Rehabilitation Considerations

Modify your exercise program to protect the healing repair:

• Reduce axial loading during deep knee flexion exercises like leg press, as this position creates maximum stress on posterior and anterior horn meniscal tissue 1
• Maintain knee range of motion and quadriceps strength through exercises that minimize patellofemoral and meniscal compression 2
• Progress loading gradually based on absence of swelling response rather than arbitrary timelines 2, 3