What treatment options are available for knee joint laxity causing the knee to give out while walking?

Treatment of Knee Joint Laxity with Instability During Walking

For knee joint laxity causing instability while walking, initiate a structured exercise program focused on quadriceps strengthening combined with a hinged realignment knee brace, as this combination addresses both the muscular weakness and mechanical instability that cause the knee to give out. 1

Initial Assessment and Diagnosis

Before treatment, obtain standing AP, lateral, and Merchant view radiographs to assess for osteoarthritis, joint space narrowing, and compartmental involvement, as the underlying pathology determines brace selection and exercise prescription 1. The sensation of the knee "giving out" typically indicates either ligamentous laxity, quadriceps weakness, or unicompartmental osteoarthritis with mechanical instability 1.

First-Line Treatment: Exercise Therapy

Quadriceps strengthening is the cornerstone of treatment for knee instability, with statistically significant and clinically important effects on both pain and function. 1

Specific Exercise Protocol

• Start with isometric exercises (quad sets and short-arc quad sets from 0-30 degrees) to avoid pain during knee extension 2
• Progress to long-arc quad sets and closed-chain exercises (partial squats to 30 degrees) as pain allows 2
• Frequency: 3-5 times per week, 20-60 minutes per session at moderate intensity 2
• Include hip girdle strengthening (both legs, regardless of which knee is affected) as proximal weakness contributes to knee instability 1
• Add low-impact aerobic exercises (walking, cycling) with effect sizes of 0.52 for pain relief and 0.46 for disability reduction 1

The evidence shows quadriceps strengthening produces clinically meaningful improvements, though not all included studies were high-quality RCTs 1. Importantly, exercise must be sustained—"small amounts often" linked to daily activities rather than isolated events 1.

Mechanical Support: Bracing for Instability

For patients with ligamentous laxity or unicompartmental osteoarthritis causing instability, a hinged realignment knee brace is strongly recommended over simple knee sleeves. 1

Brace Selection Algorithm

• For unicompartmental disease with varus/valgus instability: Use a realignment brace (valgus brace for medial compartment OA, varus brace for lateral compartment OA) 1

  • Reduces external knee adduction moment by 10-20% 1
  • Provides superior pain reduction compared to neoprene sleeves at 6-month follow-up 1
  • Single-upright braces have lower profile and better aesthetics but less stabilization; double-upright designs provide more stability for incompetent ligaments 1

• For ligamentous laxity without compartmental disease: Use a functional hinged knee brace with rigid uprights 2

  • Reduces lateral compartment loading by 11-17% 2
  • Provides 4-6 weeks of functional support 2

• For tricompartmental OA: Realignment braces are NOT recommended; consider total knee arthroplasty evaluation instead 1, 2

Proper Brace Fitting

• Measure thigh circumference 6 inches above patella and calf at widest point for sizing 2
• Don the brace slightly superior to desired position (it will settle with use) 1
• The superior calf strap is most important for maintaining brace position—tighten this first 1
• Avoid over-tightening straps, which reduces compliance 2

Critical caveat: Patients must be comfortable with wearing a brace before prescription—if they express concern about appearance during initial trial, compliance will be poor 1. Low-profile single-upright designs improve acceptance 1.

Adjunctive Treatments

Weight Loss (if BMI >25)

Recommend minimum 5% body weight reduction through dietary modification and exercise, with effect size of 0.69 for functional improvement on WOMAC function subscale 1. This provides benefits beyond knee symptoms 1.

Walking Aids

Use a cane in the contralateral hand to reduce loading and increase participation 1. This is strongly recommended for patients with instability, as it provides immediate mechanical unloading 1.

Patellar Taping

Consider medial patellar taping for short-term pain relief (immediately and up to 4 days), though this does not address the underlying laxity 1.

Manual Therapy

Manual joint mobilization combined with exercise produces better outcomes than exercise alone, increasing knee dorsiflexion ROM and decreasing pain in the short term 2.

Pharmacologic Adjuncts

• Acetaminophen as first-line for mild-to-moderate pain, providing relief comparable to NSAIDs without gastrointestinal side effects 2
• NSAIDs as adjunctive therapy only, not primary treatment 1, 2
• Intra-articular corticosteroid injection if inadequate response after 3 months of conservative treatment 1

When to Consider Surgery

Surgical referral for total knee arthroplasty should be considered only after:

1. Failure of all appropriate conservative options (exercise, bracing, weight loss, pharmacologic management) 1
2. End-stage OA with minimal or no joint space 3
3. Inability to cope with pain despite conservative measures 3

For isolated ligamentous laxity without OA, ligament reconstruction may be considered if conservative management fails after 12 months, particularly in younger active patients 4.

Critical Pitfalls to Avoid

• Do not prescribe braces without ensuring patient commitment—show sample braces in clinic first 1
• Do not use prolonged immobilization (>10 days)—short-term rigid support is acceptable for acute injuries, but functional bracing with exercise produces better outcomes 2
• Do not prescribe realignment braces for tricompartmental OA—they work best for unicompartmental disease 2
• Do not rely on bracing alone—exercise therapy must be the foundation of treatment 1
• Avoid holding breath during exercises—this increases intra-abdominal pressure and cardiovascular stress 2