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بسم الله الرحمن الرحيم:

بسم الله الرحمن الرحيم




DEFINITION Lateral patellar compression syndrome is a syndrome that is characterized clinically by patellar pain and radiographically by a patella that is centered in the sulcus , and Pain is aggravated by flexion activities without true instability.

Anatomy and Biomechanics :

Anatomy and Biomechanics -The patella is the biggest sesamoid bone in the human body, It is the link from the powerful quadriceps muscle to the patellar tendon. -Only the superior two thirds of the patella have an articular surface. The distal pole is extraarticular . patellar anterior surface is convex, and on its articular side, the patella is divided by a longitudinal median ridge. This ridge divides the patella into medial and lateral facets. -The trochlea is situated in the distal part of the femur, the normal trochlea is formed by medial and lateral facets, divided by the trochlear groove . - The quadriceps muscle is formed by four parts: rectus femoris , vastus medialis , vastus lateralis , and vastus intermedius . -On the lateral side, the superficial oblique retinaculum runs from the iliotibial band to the patella.


Causes Malalignment of the lower limb as increased Q angle, tight lateral retinaculum , tight gastrocnemius or hamstring muscles.


Symptoms -Pain is dull, poorly localized, and increased by activities that overload the patellofemoral joint , like stair climbing , squatting, and prolonged sitting with knee flexed. -Swelling -Symptoms onset may follow minimal direct trauma or twisting injury. -Patients may complain of momentary catching or locking


Signs Inspection : squinting of the patella, a mild knee varus may be present, or foot pronation . Patient is asked to maintain a half squat for 10 seconds, this is painful while full squat is less painful. Palpation : Crepitus is noted during knee extension against resistance and classified into mild moderate and severe. Assesment of tightness of the lateral retinaculum is done, the examiner should be able to lift the lateral border of patella until the transverse axis is tilted above the horizontal. With the knee flexed to 20 to 30 degrees, it should be possible to push the patella medially more than a quarter of its width. Effusion is not frequently found in this syndrome, and if present this is due to chondromalacic changes. Tenderness of a portion of the lateral retinaculum may be ill defined in 10%of patients, well defined pain at the medial retinaculum in most of patients 90%. PATELLAR COMPRESSION TEST , with the knee flexed 20 to 30 degrees the patella is compressed against the trochlea medially and laterally , this elicits pain when compressing medially . APPREHENSION TEST is negative in this case. There is marked tenderness at medial joint line .

Squinting of patella:

Squinting of patella

Investigations :

Investigations X ray Anteroposterior , lateral and axial views, axial view in 45 deg. are not very informative, as there is little differences in sulcus angle which is more open 139 versus 137, so is a slightly decreased congreunce angle -2 vs -8 . On the contrary Patellofemoral index … which is the ratio between the thickness of the medial to lateral patellofemoral joint space ,{it is 1.6 in normal knees and greater in LPCS} this accurate in 24% of cases.

PowerPoint Presentation:


Sulcus angle:

Sulcus angle

Lateral patellofemoral angle:

Lateral patellofemoral angle

Patellar index:

Patellar index

Congruence angle:

Congruence angle

Changes in the osseous structure:

Changes in the osseous structure The subchondral plate of the lateral facet shows increased density while that of the medial facet shows decreased density. Trabeculae of cancellous bone which are normally perpendicular to the transverse axis of patella shifts to be perpendicular to the lateral facet. A lateral osteophyte might be seen. The lateral facet is overall predominent over the medial one.

Insall’s Classification of Patellofemoral Disorders :

Insall’s Classification of Patellofemoral Disorders Presence of Cartilage Damage : Chondromalacia Osteoarthritis Osteochondral fractures Osteochondritis dissecans Variable Cartilage Damage : Malalignment syndromes Synovial plicae Usually Normal Cartilage : Peripatellar causes: bursitis, tendinitis : Overuse syndromes Reflex sympathetic dystrophy Patellar abnormalities


Treatment Conservative Rest, quadriceps exercise, knee braces and NSAIDs. Quadriceps training especially vastus medialis muscle, isometric progressive and resistive e.g. straight leg raising .

McConnell”s Rehabilitation Program:

McConnell”s Rehabilitation Program Iliotibial band stretching Foot supination exercise: in case of tight gastrocnemius , or hamstrings, orthotics may be used in running . Training of quadriceps muscle in external rotation of femur

Surgical treatment:

Surgical treatment Lateral retinacular release either open or arthroscopic.


complications Hamatoma formation, or heamoartrosis . Infection. Medial subluxation of patella. Persistence of symptoms.