Modern Study Review (AI-Generated)
High-Yield Summary
Varus knee deformity is the most common alignment abnormality encountered in total knee arthroplasty (TKA). Proper soft tissue balancing, particularly on the medial side, is critical to restore neutral mechanical alignment and optimize implant longevity and function. Advances in surgical technique emphasize a systematic medial release combined with precise component positioning to prevent complications such as patellar maltracking.
Key Diagnostic Findings
| Aspect | Details |
|---|---|
| Anatomy | Medial structures: meniscotibial ligament, medial meniscus, deep MCL, posteromedial capsule, PCL, semimembranosus insertion, superficial MCL, pes anserinus. |
| Clinical Presentation | Varus deformity with medial joint space narrowing, often associated with medial compartment osteoarthritis and ligament contracture. |
| Imaging | Weight-bearing long-leg alignment films show varus mechanical axis; MRI/CT may assess soft tissue contractures and component positioning pre/post-op. |
| Classification Systems | No specific varus knee classification; deformity severity often graded by mechanical axis deviation and joint space narrowing on radiographs. |
Current Gold Standard Treatment
- Non-Operative: Bracing and physical therapy have limited roles in advanced varus deformity with osteoarthritis.
- Operative Indications: Symptomatic varus knee with pain, functional limitation, and radiographic osteoarthritis refractory to conservative management.
- Surgical Technique:
- Begin with a medial soft tissue release: meniscotibial ligament, medial meniscus, deep MCL, posteromedial capsule, PCL, and semimembranosus tendon as needed.
- Subperiosteal elevation of the proximal medial tibia to mobilize superficial MCL and pes anserinus without complete release.
- Perform tibial and femoral bone cuts with attention to component rotation to avoid maltracking.
- Balance ligaments using laminar spreaders or blocks to achieve symmetric gaps.
- Address patellar tracking by lateral release, VMO advancement, or tibial tubercle osteotomy if necessary.
- Avoid detaching the patellar tendon insertion to preserve extensor mechanism integrity.
Modern Complications & Outcomes
| Complication | Notes |
|---|---|
| Patellar Maltracking | Often due to internal rotation of tibial/femoral components or malposition of patellar implant; leads to lateral subluxation. |
| Residual Varus Deformity | Inadequate medial release or improper bone cuts can cause persistent deformity and early implant failure. |
| Extensor Mechanism Injury | Avoid peeling patellar tendon insertion; rectus snip preferred if exposure is limited. |
| Neurovascular Injury | Careful preservation of superior lateral geniculate artery during lateral release reduces risk. |
| Outcomes | Proper soft tissue balancing and component positioning improve pain relief, function, and implant survival. |
Classic Clinical Notes
Varus Knee
Total Knee Replacement in the Varus Knee
- This is obviously the more common scenario than the valgus knee – should have a unified approach to the release!
- Start medially, and release everything along the medial side – meniscotibial ligament, medial meniscus, deep MCL, and all posteromedial capsule back to and including the PCL. May also need to release some of semimembranosus off the posteromedial tibia. Then subperiosteally lift off the proximal 3-5 cm of the proximal medial tibia, elevating (not releasing) the superficial MCL and the pes anserinus.
- Then cut the ACL and patellofemoral ligaments, undercut the fat pad and subperiosteally strip along the superolateral side to mid-plateau.
- Try everting the patella – watch the patellar insertion! If too tight, continue the lateral dissection a bit more, and try again. If still too tight, do a rectus snip. DO NOT PEEL THE PATELLAR TENDON INSERTION!
- Do your tibial and distal femoral and AP femoral cuts, then balance the ligaments with laminar spreaders or blocks.
If the patella subluxes laterally:
- Check your components!
- Did you internally rotate the tibial component (Harry Rubash thinks that this is very common) and thus lateralize the tubercle.
- Did you internally rotate the femoral component (or fail to externally rotate it sufficiently). This increases the Q angle and medializes the trochlear groove.
- Did you lateralize the patellar component – remember, the anatomic median ridge of the patella actually sits 3-4 mm MEDIAL to the anatomic midline of the patella – if you put it in the anatomic midline, you will be too far lateral!
- Do the lateral release +/- preservation of the superior lateral geniculate artery.
- Consider advancing the VMO – (i.e., a proximal realignment); ask yourself if this is technically possible.
- Consider doing a distal realignment – osteotomizing the tubercle and moving it medially.
Last Updated on January 24, 2026 by orthonet
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