Knee

Post TKR pain, instability and stiffness

Causes and management of post-arthroplasty knee pain, instability and stiffness.

23 questions 3 source pages

Images appear with the first question taken from each source page — tap a question to open it.

Q1What is your history in a patient with post-TKR knee pain?▸

Rule out infection: risk factors, delayed wound healing, constitutional symptoms
Nature of pain: referred, triphasic, resting
Current functional limitations

Q2What do you examine in a patient with post-TKR knee pain?▸

Local: soft tissue, sinus, ROM, FFC, instability
Systemic: hygiene

Q3What investigations are needed for post-TKR knee pain?▸

X-ray: early loosening, sizing, overhang, PFJ overstuffing, HO
Scannogram for mechanical alignment
Bloods: ESR, CRP
Aspiration: C/ST + WBC + alpha defensin (MSIS score)
CT for malrotation

Q4What are the intrinsic causes of post-TKR knee pain?▸

Infection, loosening, malalignment, instability
Loose bodies (cement, osteophyte)
PFJ problem, impingement

Q5What causes posterolateral knee pain after TKR?▸

Tibial tray overhang
Retained PL osteophyte/cementophyte - biceps tendonitis, popliteus impingement
ITB dysfunction - lateral pain with ROM 20-80 degrees

Q6What causes posteromedial pain and what are the extrinsic causes of post-TKR pain?▸

Semimembranosus tendonitis
Dual pathology (hip, foot, PVD)
CRPS, cutaneous neuromas

Q7What are the 4 Ps to mention when assessing instability after TKR?▸

Patient
Prosthesis
Procedure
Present status

Q8What history is important in post-TKR instability?▸

Initial indication and diagnosis
PMHx: connective tissue disease, inflammatory joint disease, Charcot arthropathy
Preop ROM and pre-existing laxity
Intraoperative complications
Postop compliance and recent trauma
Current function

Q9What are the components of the Knee Society knee score?▸

Pain
FFC (fixed flexion contracture)
Extensor lag
Total ROM
Alignment
Stability (AP and ML)

Q10What are the components of the Knee Society function score?▸

Walking aids
Stairs
Walking tolerance

Q11What local examination findings do you look for in post-TKR instability?▸

Soft tissue envelope, ROM, any recurvatum
Quads power
Collateral ligament testing, A and P drawer
Patellar tracking

Q12What systemic examination and gait findings are relevant in post-TKR instability?▸

generalized ligamentous laxity (generalised)
Check proprioception
Gait: varus or valgus thrusting gait
CT for implant position

Q13How do you work up and manage post-TKR instability?▸

Determine the cause
Bone: X-ray and CT
Soft tissue: examination
Rule out infection: bloods +/- aspiration

Q14What are the types of instability after TKR?▸

Flexion (AP)
Extension (ML)
Mid-flexion
Genu recurvatum
Global

Q15What causes flexion (AP) instability after TKR and how is it treated?▸

Knee dislocation (PS knees can jump the post)
Undersized femoral component --> upsize
Overresection of posterior condyle --> upsize or posterior femoral augments
Too much tibial slope --> reduce slope + use PS prosthesis
PCL insufficiency in a CR --> revision to PS knee

Q16How do you differentiate symmetrical from asymmetrical extension (ML) instability?▸

Symmetrical = bony problem (too much distal femur cut or oversized femoral implant)
Asymmetrical = ligament problem

Q17What is mid-flexion instability and what are its potential causes?▸

Malrotation when the knee is flexed between 45-90 degrees
Poorly understood
Femoral component design in the sagittal plane
Attenuation of anterior MCL
Overall geometry of the tibiofemoral joint

Q18How are genu recurvatum and global instability after TKR managed?▸

Recurvatum: fixed valgus deformity and IT band contracture; causes polio, RA, Charcot
Recurvatum: long-stemmed PS or ML constrained implant; rotating hinge for salvage as residual hyperextension may occur
Global: due to severe bone loss
Global: varus-valgus constrained prosthesis at minimum, hinged prosthesis +/- augments, megaprosthesis if severe bone loss

Q19What preoperative factors predispose to stiffness after TKR?▸

Poor preoperative range of movement
RA
Post traumatic (post-traumatic) knee
Obesity

Q20What intraoperative causes produce poor flexion after TKR?▸

Tight flexion gap: inadequate tibial slope, oversized femur, posteriorized femur
Overstuffed PFJ
Raised joint line (patella baja)

Q21What intraoperative causes produce poor extension after TKR?▸

Flexed PS component
Posterior osteophytes
Inadequate distal femur cut

Q22What intraoperative causes produce poor global ROM after TKR?▸

Big polyethylene insert
Inadequate tibial cut

Q23What postoperative complications cause stiffness after TKR?▸

Arthrofibrosis
Infection
CRPS
HO

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Post TKR pain, instability and stiffness