Knee Arthritis M17.10 715.16

ICD-9	Classification / Treatment
Etiology / Natural History	Associated Injuries / Differential Diagnosis
Anatomy	Complications
Clinical Evaluation	Follow-up Care
Xray / Diagnositc Tests	Review References

synonyms: knee osteoarthritis, Knee OA, knee degenerative joint disease, knee DJD

Knee Arthritis ICD-10

Knee Arthritis ICD-9

Knee Arthritis Etiology / Epidemiology / Natural History

120,000 per year, $25,000 each
By age 40, 90% of persons have some degenerative changes in their weight bearing joints
When minimal disease is excluded, the prevelance is @ 20%.
Risk Factors: Obesity (Felson DT, Ann Intern Med 1988;109:18) (Davis MA, J Rheumatol 1988 Dec;15:1827); Major injury; Repetitive use, such as in jobs requiring heavy labor and knee bending, probably increases the risk of knee osteoarthritis. (Felson DT, Epidemiol Rev 1988;10:1; Prior menisectomy
More common in females than males.

Knee Arthritis Anatomy

Mechanical axis of the lower extremity=line drawn from center of femoral head to center of ankle joint, should pass through center of knee. Mechanical axis of the femur = line drawn from center of femoral head to center of the femoral surface of the knee. Mechanical axis of the tibia = line from the center of the tibial plateau to the center of the ankle.
Anatomic axis=line drawn down center of tibial or femur.
Tibiofemoral angle=angle between tibial and femoral anatomic axis. Normal = 6° valgus.
Deformity can be defined as the angle drawn between the mechanical axis of the femur (i.e., the middle of the femoral head to the middle of the femoral surface of the knee) and the mechanical axis of the tibia. or as the deformity defined by the tibiofemoral angle, or the angle created between the anatomic axes of the femur and tibia.
Medial plateau is larger and concave, lateral plateau is smaller and convex
Epicondylar axis is @3 degrees externally rotated as compared to posterior condylar line
Distal femoral condyles are in 9 valgus relative to femoral anatomic axis
Tibial plateau is in 3 varus relative to tibial axis
Tibial plateau has @10 posterior slope
3 compartments =medial, lateral, patellofemoral
Medial femoral circumflex artery supplies the femoral head. (anterior humeral circumflex supplies humeral head)

Knee Arthritis Clinical Evaluation

Complain of pain and difficulty walking, climbing stairs and arising from seated position. Must assess impact of knee pain on quality of life / ADL's.
Always discuss metal allergy.
Assess Q-angle (formed by a line between the patella center extending proximally to the anterosuperior iliac spine and distally to the tibial tubercle; normal Q angle is less than 10 degrees in men and less than 15 degrees in women.)

Knee Arthritis Xray / Diagnositc Tests

Weight bearing A/P long leg films: marginal osteophytes, tibial and patellar spurring, subchondral sclerosis, joint space narrowing, flattening, squaring of the condyles and joint line angulation.
Weight-bearing lateral in extension
Flexion lateral
Merchants view(Merchant, JBJS, 1974)
Flexion weight bearing (Rosenburg JBJS, 1988)

Knee Arthritis Classification / Treatment

Kellgren and Lawrence scale
- Grade 0 = no significant changes
- Grade 1 = minute osteophyte
- Grade 2 = definite osteophyte
- Grade 3 = diminution joint
- Grade 4 = impaired joint space

Knee Arthritis Non-operative treatment

Activity modification
Exercise: low-impact excercise including isokinetic and isotonic strengthening improves symptoms, function and cartilge glycosaminoglycan content. (Roddy E, Rheumatology 2005;44:67).
Cane/walker (Blount WP, JBJS 1956;38A:695).
NSAIDs: diclofenac 150 mg/day is the most effective NSAID available at present, in terms of improving both pain and function. (da Costa Bruno R, The Lancet, Published Online: 17 March 2016). Acetaminophen is ineffective for hip and knee arthritis. May consider Diclofenac Sodium 1.5% topical (Pennsaid).
Glucosamine sulfate / Chondroitin Sulfate
Corticosteriod injections
Viscosupplementation (Hyaluronic acid injections): Can provide up to 6 months of improvement. (Arrich J CMAJ 2005;172:1039). Side effects: injection site pain, pseudoseptic reaction, infection.
Weight loss: reduces risk of OA progression and improves symptoms and function (Messier SP, Arthritis Rheum 2004;50:1501).
Platelet-rich plasma injection. (Sánchez M, Clin Exp Rheumatol 2008; 26:910).

Knee Arthritis Surgical Options

Arthroscopic debridement-indicated for pt with ,1yr symptoms, nl alignment, mechanical symptoms.
Unicompartmental knee- indications flexion cont <15, ROM >90, age >60, sedentary: rehab easier, costs less, quicker ROM, preserves ligamants/proprioception, 92% last 10yr, 15yrs = 60% working. Creates bone defect which often must be filed with allograft
High Tibial Osteotomy-for varus deformity <15, young pt, vigorous lifestyle, isolated medial arthritis, obese, ROM>90, flexion contracture<15. Need full length weight bearing radiographs. comps=under/overcorrection, AVN, patella baja, peroneal N. injuries, anterior compartment syndrome. Lasts 7-10 yrs. Osteotomy contraindicated in inflammatory arthropathy.
Distal femoral osteotomy-for valgus deformity <15, indications as above
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.
Total Knee Arthroplasty

Knee Arthritis Associated Injuries / Differential Diagnosis

TKA Follow-up Care

Knee Arthritis Review References

Fu FH, Management of Osteoarthritis of the Knee: An INternaltional Consensus, AAOS Monograph, 2003