Acute
· haemarthrosis
· fracture
· patellar dislocation
· ligamentous injury
· meniscal injury
Repetitive
· patellar tendinitis
· bursitis
· apophysitis
Late effects
· chondromalacia patellae
· lateral patellar compression
· chronic subluxation
· recurrent dislocation
· rheumatoid
· seronegative
· bone
· benign
· malignant
· soft tissue
Chondromalacia patellae
· degeneration of articular cartilage of patella
· pathological rather than clinical diagnosis
Anterior knee pain
· syndrome of pain in the anterior knee usually referable to the patellofemoral joint
· often due to patellofemoral malalignment
· often associated with chondromalacia patellae
· usually female teenage adolescent
· usually recent increase in activity
· not associated with osteoarthritis in adult life
Acute
· direct trauma
· dislocation of patella with chondral or osteochondral fracture
Chronic
· patellar malalignment
· recurrent subluxation of patella
· lateral pressure syndrome
· patellar malcongruence
· abnormal shape of patella or trochlear groove
· quads imbalance
· weakness of vastus medialis
Disease
· inflammatory arthritis
· recurrent haemarthrosis
· sepsis
Iatrogenic
· repeated intra-articular steroids
· prolonged immobilisation
· primary OA
· basal degeneration of cartilage
· changes in collagen and ground substance at deep level of cartilage
· due to decrease in sulphated polysaccharides in ground substance
· pain due to nerve endings in subchondral bone being stimulated by variations in pressure
· Grade 1
· localised softening with no break in surface
· Grade 2
· area of superficial fibrillation or fissuring
· Grade 3
· fibrillation and fissuring down to subchondral bone
· Grade 4
· loss of cartilage with exposure of subchondral bone
· nonspecific
· dull aching discomfort localised to anterior part of knee
· worse with prolonged periods of sitting in one position (cinema sign)
· worse after activity
· worse descending stairs
· may swell after activity
· may catch and lock (pseudolocking)
· patellofemoral crepitus
· features of malalignment
· features of malalignment
· NSAIDs
· quadriceps exercises
· activity modification
Correction of malalignment
· see other section
Treatment of diseased cartilage
· principles are that
· limited healing capacity for defects limited to cartilage
· exposure of subchondral bone may allow healing by fibrocartilage
Patellar shaving
· open or arthroscopic
· short-term benefit from removal of degradation products from joint
· no long-term benefit
Local excision and subchondral drilling
· for advanced disease
· better results than shaving
Patellectomy
· for extensive involvement
· reduplication of synovial fold
· represents normal embryonic synovial septum that persists into adult life
· 20% of knees have medial patellar plica at arthroscopy
· symptomatic plicae much less common (1-2%)
· mean age is 14 yrs
· medial and lateral compartments and suprapatellar pouch separated by membranes in early embryological life
· membranes involute and knee becomes single cavity
· persistence of section of membrane occurs in 20% of adults
· 5 types
1. suprapatellar chorda
· midline
2. superomedial plica
· medial side
· most common
3. superolateral plica
· lateral side
4. incomplete suprapatellar membrane
· small defect in membrane
· uncommon
5. complete suprapatellar membrane
· knee and suprapatellar pouch completely separated
· rare
· originate from medial wall of knee joint
· run obliquely down to insert in medial infrapatellar fat pad
· commonly called ligamentum mucosum
· runs from intercondylar notch
· widens and attaches to infrapatellar fat pad
· becomes pathological when becomes inflamed, stiffened and fibrotic
· inflammation can be initiated by
· single blunt trauma
· repetitive trauma
· internal derangement of knee
· causes symptoms when snaps over femoral condyle
· leads to
· synovitis
· erosion of articular cartilage over femoral condyle
· most commonly involves
· superomedial plica
· medial patellar plica
· thin pink and friable
· gross
· thickened, white and fibrotic
· histology
· chronic synovitis and enlargement of villi
Onset
· history of trauma or strenuous activity
Pain
· intemittent, dull and aching
· located anteriorly above knee joint
· increased with
· activity
· prolonged sitting
Swelling
· intermittent
· after activity
Snapping
· usually follows heavy exercise
· usually painful
· associated with
· knee flexion
· crouching
· running up stairs
Instability
· feeling of insecurity with pain and catching
Locking
· uncommon
· quadriceps wasting
· effusion
· localised tenderness over medial femoral condyle
· palpable band-like structure parallel to medial border of patella
· restriction of activities
· ROM and strengthening exercises
· arthroscopic resection
· divide plica to synovial membrane rather than completely excise
· 80-90% good to excellent results
· syn. housemaid’s knee
· due to friction between skin and patella
· occurs with repetitive kneeling
· circumscribed fluctuant swelling anterior to patella
· knee joint normal
· treat with rest
· may need excision if recurrent and troublesome
· syn. clergyman’s knee
· similar to prepatellar bursitis
· swelling superficial to patellar tendon (more distal)
· tem ‘Baker’s cyst’ may refer to either or both
· enlagement of bursa between semimembranosus and medial head of gastrocnemius
· occurs in children and young adults
· painless lump behind knee
· medial to midline
· most prominent when knee straight
· knee joint is normal
· lump may ache
· usually resolves after 1-2 yrs
· excision should be avoided
· knee joint abnormal
· rheumatoid arthritis
· osteoarthritis
· occurs after synovial herniation or rupture
· lump in midline below joint level
· may leak or rupture
· causes swollen tender calf
· may then mimic DVT
· excision should be avoided
· recurrence common unless synovial pathology corrected
· may develop sinus
· deep to insertion of patellar tendon onto tibial tiberosity
· often inflamed with Osgood-Schlatter’s disease
· occurs over medial upper tibia
· at insertion of sartorius, gracilis and semitendinosus
· usually requires excision
· related to biceps insertion into femoral head
· may be confused with ganglion from superior TF jt
· requires excision