Unicompartment Knee Arthroplasty
synonyms:
Unicompartment Knee Arthroplasty CPT
Unicompartment Knee Arthroplasty Indications
- unicompartmental OA, radiographic evidence of preservation of opposite compartment, only mild PF DJD
- Primary spontaneous osteonecrosis (secondary AVN, ie steroid use, is a contraindication
- ROM>90 degrees
- Flexion contracture <5°, angular deformity <15°.
- Minimal pain at rest
- Relatively sedentary lifestyle
- Weight <275 lb (124.7kg)
- Age >50y/o.
Unicompartment Knee Arthroplasty Contraindications
- Opposit compartmernt or patellofemoral athritis
- Fixed varus or valgus deformity >5°
- Restricted ROM
- Fixed flexion contracture
- Joint subluxation >5mm
- ACL deficiency (relative contraindication for medial compartment, contraindication for lateral compartment)
- Inflammatory arthritis
- Hemochromatosis
- Chondrocalcinosis
- Hemophilia
- Patellofemoral joint symptoms, positive patellar grind test
- Symptomatic instability
Unicompartment Knee Arthroplasty Alternatives
- Arthroscopic debridement-indicated for pt with ,1yr symptoms, nl alignment, mechanical symptoms.
- Distal Femoral osteotomy
- TKA
- High Tibial osteotomy
- Arthodesis-indicated for infection, failed TKA, young active patients, soft tissue defects, absent extensor mechanism, neuropathic joint disease. fusion in 10-15 flexion and 0-7 valgus. complications=infection, non/malunion, pain.successful in 80-90% of failed condylar components, 55% of failed hinged prosthesis.
Unicompartment Knee Arthroplasty Pre-op Planning
- shorter hospital stay, fewer serious complications, improved walking ability, lower cost, more normal gait, better quadriceps function, better knee flexion than TKA
- Arthritis progresses in other compartments which may limit long long-term outcome. Often must deal with bone deficiency in revision to TKA
- Goal = undercorrection of the mechanical axis by 2° -3° .
- Do not release MCL and allow 2mm of joint laxity in extension and flexion.
- Recreate native tibial slope.
- Femoral component should be placed perpendicular to the tibial component in the coronal plane.
Unicompartment Knee Arthroplasty Technique
- Sign operative site.
- Pre-operative antibiotics, +/- regional block.
- General endotracheal anesthesia
- position. All bony prominences well padded.
- Examination under anesthesia.
- Prep and drape in standard sterile fashion.
- Irrigate.
- Close in layers.
- femoral component should be congruent with the curvature of the anterior part of the femus to avoid patellar impingement.
- Pre-drill any holes for alignment guides to avoid subsequent tibial plateau fx
- avoid over correcting any alignment deformity to decrease progressive arthritis in adjacent compartment
Unicompartment Knee Arthroplasty Complications
- Tibial plateau fracture
- Medial collateral ligament avulsion/tear
- Stiffness
- Infection
- CRPS
- DVT / PE
- ACL rupture (related to posterior tibial slope 7°)
Unicompartment Knee Arthroplasty Follow-up care
- Post-op:
- 7-10 Days:
- 6 Weeks:
- 3 Months:
- 6 Months:
- 1Yr:
Unicompartment Knee Arthroplasty Outcomes
- Miller-Galante UKA system, modular fixed-bearing, metal-backed tibial component (Zimmer) 80% excellent, 12% good, 8% fair results. 98% survival rate at 10 years (Berger RA, JBJS AM 2005;87:999-1006)
- Oxford, meniscal-bearing UKa system 93% 15 year survival, 91% good/excellent clinical results (CORR 2005;435:171).
- Failure occurs from wear, loosing, and adjacent compartment degeneration.
Unicompartment Knee Arthroplasty Review References
- Iorio R, JBJS 2003:85:1351°
- Borus T, JAAOS 2008;16:9
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