วันศุกร์ที่ 8 พฤษภาคม พ.ศ. 2569

Complications of Total Knee Arthroplasty (TKA)

Complications of Total Knee Arthroplasty (TKA)

ภาพรวม

TKA เป็น procedure ที่ effective และ relatively safe แต่ complications อาจรุนแรงถึง life-threatening ได้

Complications สำคัญ:

  • VTE/PE
  • infection/PJI
  • neurovascular injury
  • instability
  • aseptic loosening
  • arthrofibrosis

PERIOPERATIVE COMPLICATIONS

1. Blood Loss

ปัจจุบันลดลงมากด้วย:

  • tourniquet
  • tranexamic acid
  • local infiltration analgesia

Intraoperative transfusion rate:

ใกล้ 0% ในหลายศูนย์

2. Thromboembolism (VTE)

หนึ่งใน complication ที่น่ากลัวที่สุด

Incidence without prophylaxis

  • DVT: 40–88%
  • asymptomatic PE: 10–20%
  • symptomatic PE: 0.5–3%
  • mortality: up to 2%

With prophylaxis

Symptomatic VTE ลดลงมาก

Example:

  • aspirin ~3.45%
  • enoxaparin ~1.82%

Prevention

ต้อง balance:

  • thrombosis risk
    vs
  • bleeding risk

Main strategies:

  • pharmacologic prophylaxis
  • early mobilization

3. Peroneal Nerve Palsy

Most common severe neurologic complication

Clinical findings

  • numbness
  • paresthesia
  • foot drop

Risk factors

  • severe valgus deformity
  • flexion contracture
  • prolonged tourniquet >120 min
  • external compression
  • previous spine disease (“double-crush”)

Mechanisms

  • stretch injury
  • retractor injury
  • hematoma
  • swelling
  • compression while lying in bed

Initial management

  • loosen dressing
  • flex knee 30°
  • X-ray evaluate prosthesis

Prognosis

ส่วนใหญ่ recovery ภายใน:
12–18 months

4. Tourniquet-related Ischemic Injury

Risk เพิ่มเมื่อ:

  • cuff pressure สูง
  • ischemic time นาน

Principle:

lowest pressure + shortest time possible

5. Arterial Injury

Rare แต่ severe

Incidence

~0.013–0.17%

Most common vessel:

  • popliteal artery

Clinical presentations

  • acute hemorrhage
  • limb ischemia
  • chronic swelling/pain
  • pseudoaneurysm

Important point

Mortality + PJI risk สูงขึ้นมากเมื่อเกิด vascular injury

6. Wound Healing Problems

Risk factors:

  • DM
  • obesity
  • RA
  • poor circulation
  • prior incision

Persistent drainage

ต้อง:

  • exclude infection
  • aspiration/culture
  • irrigation & debridement if needed

May require:

  • plastic surgery consult

7. Surgical Site Infection / PJI

Incidence

~1%

Risk factors

  • diabetes
  • obesity
  • smoking
  • malnutrition
  • inflammatory arthritis

Classification

Acute:

  • within 3–6 weeks

Late:

  • often hematogenous

8. Intraoperative Fracture

Incidence

~0.39%

Stable fracture:
→ observation

Unstable:
→ fixation

Outcomes generally excellent

9. Ligament Injury

Most common:

  • MCL injury

Incidence:
~1.2%

Treatment

  • primary repair
  • hinged brace
  • increased prosthetic constraint

10. Myocardial Infarction

Highest risk:

  • 2–4 weeks postop
  • age ≥80

Important:
Complication after first staged TKA predicts recurrence risk in second procedure

INTERMEDIATE & LATE COMPLICATIONS

11. Aseptic Loosening

หนึ่งใน most common causes of failure

Risk factors

  • younger age (<50)
  • polyethylene wear
  • poor fixation
  • implant stress

Diagnosis

Serial X-ray:

  • progressive radiolucency >2 mm

Workup สำคัญ:

ต้อง exclude PJI

Labs:

  • WBC
  • CRP
  • aspiration if suspicious

Management

Symptomatic + infection excluded:
→ revision TKA

12. Joint Instability

Major cause of revision

Types

  • flexion instability
  • extension instability
  • combined

Risk factors

  • RA
  • connective tissue disease
  • osteoporosis
  • neuropathy
  • obesity
  • ligament imbalance

Clinical presentation

  • pain
  • recurrent effusion
  • giving way

Treatment

Usually:

  • revision to constrained implant

Sometimes:

  • bracing

13. Late/Chronic PJI

Usually hematogenous

ต้องสงสัยใน:

  • chronic pain
  • swelling
  • effusion
  • loosening

14. Patellofemoral Complications

Common reason for reoperation

Includes:

  • instability
  • loosening
  • fracture
  • extensor rupture
  • patella clunk
  • anterior knee pain

Patellofemoral Instability

Incidence

1–20%

Diagnosis

  • sunrise/Merchant view
  • CT for component rotation

Causes

  • malrotation
  • malalignment
  • soft tissue imbalance

Treatment

  • lateral release
  • realignment
  • revision component

Patellar Component Loosening

Associated with:

  • osteolysis
  • malposition
  • instability

Symptomatic:
→ revision

Patella Fracture

Incidence

~0.3%

Causes

  • component malposition
  • AVN
  • trauma
  • excessive flexion

Treatment depends on

  • displacement
  • component fixation
  • extensor mechanism integrity

Extensor Mechanism Rupture

Feared complication

Usually:

  • patellar tendon rupture

Clinical presentation

  • inability to extend knee
  • extensor lag

Diagnosis

  • X-ray
  • MARS MRI/CT

Treatment

  • surgical repair/reconstruction

Patella Clunk Syndrome

Classic finding:

clunk during extension from 60° → 30°

Cause:

  • fibrous nodule under quadriceps tendon

Anterior Knee Pain

Possible causes:

  • patellofemoral pathology
  • unresurfaced patella

15. Periprosthetic Fracture

Common in:

  • osteoporosis
  • RA
  • arthrofibrotic knees
  • revision TKA

Femoral fractures

Supracondylar most common

Risk:

  • anterior femoral notching

Treatment

Stable + well-fixed:
→ nonoperative

Displaced/loose:
→ ORIF or revision

Tibial fractures

Rare

Treatment based on:

  • displacement
  • implant stability

16. Polyethylene Wear

Causes:

  • activity
  • obesity
  • malalignment
  • implant design

Clinical

  • pain
  • swelling
  • progressive deformity

Diagnosis

X-ray:

  • joint space narrowing

Management

  • observe
  • liner exchange
  • revision if osteolysis/loosening

17. Osteolysis

Usually from polyethylene wear debris

If associated with loosening:
→ revision surgery

If stable:
→ serial X-rays

18. Arthrofibrosis

Postoperative stiffness from scar tissue

Functional flexion requirements

Activity

Flexion needed

Walking

67°

Stair ascent

83°

Stair descent

100°

Rise from chair

93–105°

Risk factors

Best predictor:

poor preop ROM

Other causes:

  • infection
  • malposition
  • poor rehab
  • pain

Treatment

  • manipulation under anesthesia
    (best within 3 months)
  • arthroscopic lysis
  • revision if malpositioned implant

19. Persistent Pain & Dissatisfaction

~20% patients:

  • dissatisfied
    or
  • persistent moderate/severe pain

Possible causes

  • unrealistic expectations
  • technical failure
  • referred pain
  • pain catastrophizing
  • instability
  • infection
  • metal hypersensitivity

20. Metal Hypersensitivity

Metals:

  • cobalt
  • chromium
  • nickel

Symptoms

  • persistent pain
  • effusion
  • rash

Diagnosis of exclusion:

exclude infection/loosening/instability first

Testing

Controversial:

  • patch testing
  • lymphocyte transformation testing

No role for routine screening currently

High-yield Clinical Pearls

  • DVT risk after TKA without prophylaxis extremely high
  • Foot drop after TKA = peroneal nerve palsy until proven otherwise
  • Severe valgus/flexion contracture → high peroneal nerve risk
  • Persistent wound drainage must be treated aggressively to prevent PJI
  • Most important step in aseptic loosening workup = exclude infection
  • Instability is a major cause of revision TKA
  • Patellofemoral complications are common causes of reoperation
  • Arthrofibrosis responds best to early manipulation (<3 months)
  • About 20% of patients remain dissatisfied despite technically successful TKA
  • Metal hypersensitivity is rare and remains a diagnosis of exclusion

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