Complications of TKR

Intraoperative



Arterial damage

  • Rare
  • Both direct surgical injury and tourniquet-induced atherosclerotic embolism happen
  • Tourniquet should not be used if there is :
    • Documented atherosclerotic disease
    • Absent distal pulses
    • Radiographic arterial calcification



Peroneal nerve damage

  • 3%
  • Most common in correction of combined flexion – valgus deformity 
  • Can occur intra or post-operatively due to :
    • Direct injury
    • Traction
    • Hematoma
    • External pressure from splint or dressing
  • Majority of cases gain partial recovery
    • 50% achieve full recovery
      • 80% if there has been partial nerve palsy
      • 35% if there has been complete nerve palsy
    • Exploration of peroneal nerve is indicated if no recovery by 3 months



Blood loss

  • 1000-1500 ml



Fat embolism

  • 3%
  • Associated with stemmed intra-medullary components and guides
  • Bilateral one stage TKR increases the chance

Perioperative



Wound healing problems

  • RA
  • Diabetes
  • Haematoma
  • Low albumin
  • Leukopenia
  • Malnutrition
  • Obesity 



Infection

  • Affects 1 – 2.5% of TKRs
  • Classification
    • Acute infection
      • < 3 weeks from operation
      • Confined to joint space
      • Usually infection has not invaded bone-implant interface
    • Chronic infection : >3 weeks from operation
    • Hematogenous
      • May happen years after operation
      • Source of infection is a remote, usually hidden site
  • Increased incidence in
    • RA
    • Obesity
    • UTI
    • Previous knee surgery
    • Accompanying skin ulcer
  • Presents with
    • Persistent effusion and pain
    • Loosening
    • Local inflammatory signs
    • Drainage
    • Sepsis
  • Diagnosis
    • Culture
      • The gold standard
      • Intra-operative results are more reliable
      • 25% false negative result for aspiration
    • CRP, ESR, WBC
      • Usually raised in acute infections
      • Generally not reliable for making diagnosis, but normalisation of previously raised amounts is a positive indicator for re-implantation
    • Indium and tri-phasic bone scans are helpful
  • Bacteriology
    • 35 – 40% due to Staph aureus
    • Low virulent organisms :
      • Staph epidermidis (methicillin sensitive, non glycocalyx forming)
      • Staph aureus (methicillin sensitive, non glycocalyx forming)
      • ß hemolytic strep
      • Anerobic strep
    • High virulent organisms :
      • Gram negative organisms; E. coli, Pseudomonas, Proteus and Entero-cocci
      • Staph epidermidis (methicillin resistant, glycocalyx forming)
      • Staph aureus (methicillin resistant, glycocalyx forming)
    • Others: Corynobacterium, Group B strep, Strep faecalis
  • Treatment
    • Long term antibiotic suppression if :
      • Prosthesis removal not feasible
      • Low virulence or highly sensitive organisms 
      • Prosthesis not loose
      • Medically unfit patient for operation
      • Antibiotic therapy can be continued orally and indefinitely
    • Debridement, irrigation and suction
      • Good choice if :
        • <4 weeks passed operation
        • Well-fixed prosthesis
        • Gram positive, sensitive organism
        • No sinus tract
      • Poly insert should be removed and a new one replaced later
      • Some propose complete synovectomy as well
      • 4-6 weeks of IV antibiotic therapy recommended
      • Success rate
        • 90% if <3 weeks
        • 20-30% if >3 weeks
    • Resection arthroplasty
      • Good choice If :
        • There is excessive bone loss
        • Low demand patient with limited rehab potential
        • Resistant case
      • Requires prolonged cast/bracing
      • Results are unpredictable
      • Aim for 7° valgus and 15° flexion
      • If unhappy, proceed to arthrodesis
    • Arthrodesis 
      • Painless stable extremity with usually 2 – 8 cm shortening 
      • Often difficult, due to bone loss
      • Resurfacing implants need less bone loss 
      • 75% fusion rate with external fixation
      • 80% fusion rate with internal fixation, e.g. IM nail, plating
      • Internal fixation requires a clean wound
      • Fusion usually takes 4 – 6 months
    • Amputation
      • Life threatening infection
      • Multiple failed attempts
      • Elderly, non ambulatory patient
    • Immediate one stage re-implantation 
      • 35% success rate
    • Two stage re-implantation


      • Implants removal, followed by 6 weeks antibiotic therapy and re-implantation in a second stage
      • Insert an antibiotic impregnated spacer
      • Re-implant prosthesis between 6 weeks and 3 months after debridement
      • Wait until operation site and inflammatory indices appear normal
      • Re-implantation is difficult after about 3 months due to :
        • Soft tissue contracture 
        • Extensor lag
        • Poor power is the most common post-operative problem
      • Good or excellent results in 75%

Postoperative



DVT and PE

  • Asymptomatic DVT is evident on venography of 50 – 70% of patients
  • Asymptomatic PE in 15% of patients
  • Symptomatic PE in 1-3% of patients
  • A combination of both mechanical and pharmacological prophylaxis is the most effective
  • Prophylaxis with Warfarin brings down complication rate to 17%



Loss of Quadriceps power


Decreased ROM

  • Defined as <90 flexion
  • The single most important predictor of post operative ROM is pre-operative ROM
    • Post-op ROM is equal to pre-op ROM ± 10°
    • Usual range is 0-110°
  • Fixed Flexion Deformity (FFD)
    • Will not stretch out automatically, if not addressed at the time of surgery
    • Most post-op FFDs are result of hamstring spasm
    • Post-operative FFD <30° usually resolves by 2 years
  • CPM
    • Has no proven benefit for increasing overall ROM
    • It may improve early ROM and prevent DVT
  • Flexion <90° at 6 weeks may need MUGA
    • Arthrofibrosis is the usual culprit
    • Adhesions occur in medial and lateral gutters



Fractures

  • 1%
  • Occurs within 15 cm of the prosthesis or adjacent to prosthesis stem
  • Femur > Tibia
  • More common in
    • Revision surgery
    • Osteoporosis
    • Presence of stress risers; e.g. femoral notching
  • ORIF should be reserved for patients in whom
    • There is no osteopenia
    • Stable fixation can be achieved
    • There is a well-fixed implant
    • Fracture has disrupted implant interface
    • Satisfactory closed reduction cannot be maintained



Problems of the patella

  • The most common complication after TKR
    • Occur in 10% of TKR patients
    • Comprise 50% of all TKR complications
  • Patellar clunk (tethered patella syndrome)
    • Impingement of a fibrous nodule developed at the junction of patella and quadriceps tendon in intercondylar notch
    • The cause of nodule formation is not clear
    • Nodule impinges in flexion, prevents extension and is released at 30-45° of extension with a clunk
    • Only happens in posterior stabilised implants
    • Manage with arthroscopic debridement
  • Fractures of the patella
    • Secondary to :
      • AVN
      • Direct trauma
      • Under resection (marked stresses over the patella)
      • Over resection (weak patella)
      • Patellar pegs create stress risers (some use multiple small pegs rather than one large peg)
    • Treatment
      • Minimal displaced fracture : treat in extension splint for 6 weeks
      • Displaced fracture with a well-fixed patellar component : ORIF 
      • Displaced fracture plus loose component : remove implant as bone stock is usually too poor for re-implantation
      • Severely comminuted facture : partial or total patellectomy
  • Patella baja
    • Caused by raised joint line
    • Limits knee flexion due to patellar impingement
    • Commonly seen in patients who have had :
      • Previous tibial osteotomy
      • Previous proximal tibial fracture
      • Tibial tubercle transfer
    • Managed by :
      • Lowering joint line
        • Augment femoral side and resect tibial side
        • Gives partial relief
      • Placing the patellar insert superiorly
      • Trimming patellar and tibial poly inserts
      • Patellectomy
  • Patellar tendon avulsion
    • Increased risk in
      • Revision
      • Prior HTO
    • Treat with
      • Primary repair plus protective cerclage wiring
      • Use graft in irreparable cases
      • Knee fusion is the last resort
  • Patello-femoral instability
    • Causes include :
      • IR of tibial or femoral component
      • Medial translation of femoral component
      • Lateral placement of the patellar component
      • Residual valgus deformity
      • Raised joint line
      • Inadequate resection of bone in resurfacing (too thick patella)
    • Treatment
      • If there is malrotation of components, perform revision surgery
      • If there is no malrotation :
        • Lateral release
        • Medial reefing
      • Rarely distal realignment becomes necessary



Loosening

  • The most common long-term complication
  • Incidence increases with time 
  • More associated with constrained prostheses
  • Accelerating factors :
    • Malalignment
    • Poor cement techniques
  • Debris–induced, macrophage-initiated osteolysis and loosening are considerably rare in TKR, but may be a problem with patellar prostheses
    • Threefold larger wear particles are produced in a shearing, less-conforming environment of knee
    • Large particles are less likely to induce a macrophage response and lead to a lower rate of aseptic loosening

References

  • Di Cesare : Knee. In Spivak JM, Di Cesare PE, Feldman DS : Orthopedics; A Study Guide; 1999
  • McPherson EJ : Adult Reconstruction. In Mark D. Miller : Review of Orthopedics; 2008
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