Sonography of Knee and Calf Pain: the differential considerations Dr. Lisa L. S.Wong Consultant Radiologist St Paul s Hospital Outline Ultrasound techniques Common pathologies in calf and posterior knee pain Common pathologies in anterior, medial and lateral knee pain Advanced Specialty Program for Diagnostic Radiographers in Ultrasonography, Musculoskeletal Ultrasound Symposium, 6 th November 2010 Differential Considerations in Calf and Posterior Knee Pain Deep venous thrombosis Muscle injury e.g. strain or contusion Achilles tendinosis or tendon tear Ruptured Baker s cyst Differential Considerations in Calf and Posterior Knee Pain Deep venous thrombosis Muscle injury e.g. strain or contusion Achilles tendinosis or tendon tear Ruptured Baker s cyst Ultrasound Techniques and Approach Linear transducer High resolution >10 MHz Know anatomical landmarks to identify different musculoskeletal structures Extended field-of-view allows better display of muscle anatomy and pathology and enhances cross-specialty communication Ultrasound Techniques and Approach Clinical history very important Ultrasound palpation Comparison with contralateral side is important to pick up subtle changes Correlate with radiographs when necessary
Differential Considerations in Calf Pain Deep venous thrombosis Muscle injury Achilles tendon tear Ruptured Baker s cyst Direct MUSCLE INJURY Contusion Laceration Indirect DOMS (Delayed Onset Muscle Soreness) Strain MUSCLE CONTUSION Direct blunt trauma to muscle Most common lower extremities Early mobilization rapid recovery Can grade by amount of restricted motion MUSCLE CONTUSION Ultrasound features: Increased muscle girth Typically no significant fiber disruption Increase echogenicity depending on amount of haemorrhage MUSCLE LACERATION Ultrasound features: Abrupt muscle fibers disruption Sharp interphase at the muscle laceration Increase echogenicity depending on amount of haemorrhage Direct MUSCLE INJURY Contusion Laceration Indirect DOMS (Delayed Onset Muscle Soreness) Strain
DELAYED ONSET MUSCLE SORENESS (DOMS) Reversible structural damage within hours No history of trauma nor acute onset of pain Pain 24-72 hours post exercise People unaccustomed to vigorous exercise Initiation or resumption of training Self limited subsides within 1 week usually No permanent damage to muscle function DELAYED ONSET MUSCLE SORENESS (DOMS) Ultrasound Usually normal May have perifascial fluid-like collections MUSCLE STRAINS Indirect injury excessive stretch during muscle contraction Muscles at risk crossing two joints eccentric (lengthening) contraction E.G. gastrocnemius, hamstrings, quadriceps Predispositions Lack stretching warm up Lack conditioning fatigue Steroid injections MUSCLE STRAINS Diagnosis usually straightforward Pain and tenderness Patient feels intense sudden pain - pop May feel gap Musculotendinous junction is the weak link May have extensive bleeding First degree MUSCLE STRAINS No significant loss of strength or ROM Typically less than 5% fiber disruption Second degree partial tear Partial loss strength Can be subdivided by extent Third degree complete tear 1 st DEGREE MUSCLE STRAIN ULTRASOUND Swollen muscle with either increased (blood products) or decreased echogenicity (oedema) Subtle changes picked up by comparing with contralateral DDx: muscle contusion (differs in mechanism of injury) infection or inflammation (myositis) iatrogenic (e.g. RT)
RT GASTROC LT GASTROC GASTROCNEMIUS STRAIN 2 nd DEGREE MUSCLE STRAIN Second degree partial tear involves < 1/3 of fibres - low grade involves 1/3 to 2/3 of fibres moderate grade involves more than 2/3 of fibres high grade T2W GASTROCNEMIUS STRAIN 2 nd DEGREE MUSCLE STRAIN SOLEUS STRAIN ULTRASOUND Swollen Architectural distortion at myotendinous junction Heterogeneous echogenicity due to blood products and oedema Muscle disruption Haematoma Perifascial fluid LS TS
2 nd DEGREE MUSCLE STRAIN 2 nd DEGREE MUSCLE STRAIN ULTRASOUND Haematoma follow-up necessary to exclude haemorrhage associated with an intramuscular tumour 3 rd DEGREE MUSCLE STRAIN 65 y.o. female with calf pain Third degree complete tear complete discontinuity of fibres retraction of fibres haematoma at site of rupture chronic muscle atrophy
MUSCLE-APONEUROSIS TEAR Commonest site in the calf between the distal part of medial head of gastrocnemius and soleus muscle - Tennis leg Characteristic Pop Common in sports requiring jumps or speed MUSCLE-APONEUROSIS TEAR Ultrasound: Rounding of distal gastrocnemius fibres at the myoaponeuroticattachment with the soleus Fluid/haematoma along the aponeurosis Perifascial fluid Echogenic oedema in the muscles and subcutaneous fat NORMAL Achilles Tendon Conjoined tendon of medial & lateral gastrocnemius and soleus muscles Lacks tendon sheath, enclosed by paratenon Tear most common at myotendinous junction in lower calf Sudden pain at lower calf as if being kicked by someone May have pop sound Ultrasound Achilles Tendon Tear Ruptured tendon stump wavy, retracted Oedema increased echogenicity Fluid or haematoma at tear gap Report Site of tear from calcanealinsertion Complete vs partial (beware of intact plantaris tendon) Tear gap Dynamic study apposition of the tendon stumps Achilles Tendon Tear
Achilles Tendon Tear Achilles Tendon Tear Dynamic study Dynamic study
Dynamic study Achilles Tendon Tear Achilles Tendon Tear Plantaris Follows medial side of Achilles to insert either anteromedially on Achilles or on calcaneus Plantaris absent in 7-10% Intact plantaris tendon in the presence of full thickness Achilles tendon tear may be mistaken as partial Achilles tendon tear Baker s cyst Synovial cyst in posterior aspect of knee Formed by escape of effusion from the knee with subsequent trapping of fluid by one-way valvular mechanism in the gastrocnemius-semimembranosus bursa Causes: Large effusion e.g. internal derangement of the knee Arthritis e.g. rheumatoid arthritis Clinically: Asymptomatic if small Complained of mass if large Sudden severe pain if rupture Ultrasound Location: between the medial gastrocnemiusmuscle and semimembranosusmuscle/tendon
Baker s Cyst Baker s Cyst Positioning of the knee Patient lie flat and knee flexed Placed knee over a triangular soft pad Manoeuvres to deliver stress to certain ligaments e.g. valgus stress to detect MCL injury
Differential Considerations in Knee Pain Problem-based approach Ultrasound good for superficial structures Know limitations of ultrasound MRI if suspect deep intra-articular knee pathology Differential diagnoses Anterior knee pain Muscle Injury Quadriceps muscles Mucoiddegeneration or tear Quadriceps tendon Patellar tendon Patellar retinaculi Distended suprapatellar bursa underlying internal joint derangement, synovitis Pre-patellar bursitis Patellar cartilage tear (ultrasound only see femoral trochlear cartilage ) MRI better Patellar fracture Anterior compartment muscles Quadriceps muscles Rectus femoris, vastus medialis, vastus lateralis and vastus intermedius Common tendon inserting to superior pole of the patella Garrett, Jr. W.E. Am. J. Sports Med 1996
Ruptured rectus femoris muscle Ruptured rectus femoris muscle with retracted tendon Patellar Tendon Jumper s Knee Overuse syndrome due to sudden or repetitive extension of the knee Athletes involved in kicking, jumping and running Spectrum of patellar tendinosis (mucoid degeneration or fibrinous necrosis) and tear +/- secondary inflammatory response at patellar insertion Ultrasound features Hypoechoic thickening of the PT Loss of normal fibrillary pattern Increased vascularity Jumper s Knee 22 y.o. anterior knee pain after sports session at school Avulsion of medial patellar retinaculum from patella
Effusion in suprapatellar bursa Differential diagnoses Medial Knee pain Muscle injury Vastus medialis muscle Mucoid degeneration or tear of Medial collateral ligament Medial patellar retinaculum Pes anserinus goose -feet Sartorius, Gracilisand Semitendinosus tendons Medial meniscus pathology (MRI should be performed) Medial compartment cartilage pathology (MRI)
MCL Tear Differential diagnoses Lateral knee pain Muscle Injury Vastus lateralis Mucoid degeneration or tear of: Iliotibial band Lateral collateral ligament Biceps femoris tendon Popliteus tendon Lateral patellar retinaculum Lateral meniscus pathology ( better with MRI) Lateral Landmarks and Structures Lateral Landmarks Lateral femoral epicondyle Fibular head Gerdy s tubercle of tibia Structures Iliotibial band G. tubercle Biceps femoris tendon inserts on fibular head Lateral collateral ligament lateral femoral epicondyle to fibular head Popliteus tendon inserts on femoral sulcus deep to LCL Lateral meniscus BF ITB FEMUR TIBIA Grant s Atlas of Anatomy
FIBULA FEMUR TIBIA PERONEAL NERVE PERONEAL NERVE TUMOUR PERONEAL NERVE TUMOUR
HETEROTOPIC OSSIFICATION Preferred term over myositis ossificans Risk of development related to injury severity Complication of contusion Most common second decade Symptoms may last for months pain, swelling, tenderness and palpable mass Most common quadriceps and brachialis muscles May spontaneously resolve HETEROTOPIC OSSIFICATION US findings Echogenic foci or interphase due to calcification Sometimes better than radiographs in subtle cases Correlation with radiographs or even CT Peripheral rind of mineralisation Cortex of adjacent bone intact and not in continuity with lesion Conclusion Ultrasound is excellent for differentiating causes of calf pain Ultrasound is good for superficial structures and pathology of the knee but limitations for assessing deep structures of the knee Problem-based approach is recommended THANKYOU!