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Unicompartmental Knee Arthroplasty 27446

 medial compartment arthritis xray

unicompartment knee xray

failed unicompartment knee arthroplasty

synonyms:uni, unicompartmental knee replacement, partial knee replacement, unicompartment knee arthroplasty

Unicompartment Knee Arthroplasty CPT

Unicompartment Knee Arthroplasty Indications

  • Primary indication is anteromedial knee ostoearthritis.
  • 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 compartment athritis
  • Lateral facet patellofemoral arthritis with bone on bone contact, grooving, patellar subluxation
  • Fixed varus or valgus deformity >5°
  • Restricted ROM
  • Fixed flexion contracture
  • Joint subluxation >5mm
  • ACL deficiency 
  • MCL deficiency
  • Inflammatory arthritis
  • Hemochromatosis
  • Chondrocalcinosis
  • Hemophilia
  • Symptomatic instability

Unicompartment Knee Arthroplasty Alternatives

  • Arthroscopic debridement-indicated for pt with ,1yr symptoms, normal 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
  • Supine 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 femur 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

  • Lateral Compartment arthritis progression
  • Poly dislocation
  • Pain
  • Loosening
  • Wear
  • Patellofemoral pain / arthritis (rare)
  • 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:
  • It is not uncommon for patients to have some medial proximal tibia or knee pain for the first 6-12 months post op.  This generally resolves with observation and conservative care. 

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.
  • Decreased survivorship for UKA than TKA. 
  • No differences in survivorship between fixed- or mobile-bearing UKAs. 
  • Mobile-bearing UKA have 1% risk of bearing spinout. 
  • UKA has higher revision rate, shorter hospital stay, lower perioperative complications when compared to TKA (Bolognesi MP, JBJS 2013;95:2049)

Unicompartment Knee Arthroplasty Review References

  • Iorio R, JBJS 2003:85:1351°
  • W-Dahl A, Robertsson O, Lidgren L, Miller L, Davidson D, Graves S. Unicompartmental knee arthroplasty in patients aged less than 65. Acta Orthop. 2010 Feb;81(1):90-4. doi: 10.3109/17453671003587150.
  • Borus T, JAAOS 2008;16:9
  • Goodfellow J, O’Connor J, Dodd C, Murray D, eds. Unicompartmental Arthroplasty with the Oxford Knee. Oxford, UK: Oxford Medical Publications; 2006.
  • Murray DW, Goodfellow JW, O'Connor JJ. The Oxford medial unicompartmental arthroplasty: a ten-year survival study. J Bone Joint Surg Br. 1998 Nov;80(6):983-9.


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