Musculoskeletal Investigations

Musculoskeletal investigations

Mr. Harish Kurup

Consultant in Orthopaedics

PilgrimHospital, Boston

Blood tests

Full blood count: This is the usual baseline investigation for any condition. Also useful in preoperative screening. A raised white cell count suggests possible infection.

ESR & CRP: A normal ESR & CRP excludes an infective process. Useful in monitoring treatment of bone / joint infections and infected joint replacements.

Alkaline phosphatase: useful in Rickets, bone tumours including secondaries.

Calcium / Phosphorus: Useful in Rickets/ otseomalacia and parathyroid disorders.

Urine Bence-Jones protein and serum electrophoresis: are useful diagnostic tests in multiple myeloma.

X-ray

Virtually all musculoskeletal conditions need X-rays of the involved part. Two views (usually 90 degrees from each other like Antero-posterior and lateral views) are needed for a three dimensional profile of the involved area. Some fractures like toddler’s fracture may be missed if only one view is taken. In case of fractures you need to include the joint above and below. Some fractures are difficult to visualize in the first X-ray such as scaphoid fracture and so needs repeat X-rays after 2 weeks. X-rays do have risk of radiation, so better avoided in pregnant women.

CT scan

CT scans are used for assessing bony pathology. Useful to detect occult fractures, to evaluate fractures in detail and in assessment of bone lesions. Radiation risk is much higher than X-rays.

MRI

MRI scans are used for assessing soft tissue pathology and have no risk of radiation. Useful for diagnosis of back pain, rotator cuff pathology, meniscal and knee ligament injuries along with many others.

Bone scan

A radioactive isotope(technetium-99m-MDP) is injected into blood stream which has affinity for hydroxyapatite crystals in bone. The uptake of the substance is measured by gamma camera which can pin point area of pathology and further investigations can be targeted to this area. Also useful in detecting bony secondaries from common cancers.

DEXA scan

A DEXA scan is used to measure the density of bones and diagnose osteoporosis. DEXA stands for 'dual energy x-ray absorptiometry'. A DEXA scan uses low energy x-rays. A machine sends x-rays from two different sources through the bone being tested. Bone blocks a certain amount of the x-rays. The denser the bone is, the fewer x-rays get through to the detector. By using two different x-ray sources rather than one it greatly improves the accuracy in measuring the bone density. Patients over 75 with previous fragility fractures (such as hip fracture or vertebral fracture) do not need a DEXA scan before starting osteoporosis treatment.

Nerve conduction tests

A nerve conduction study is a test commonly used to evaluate the function of the motor and sensory nerves. Most common orthopaedic indication for nerve conduction study is carpal tunnel syndrome. Motor NCS are performed by electrical stimulation of a peripheral nerve and recording from a muscle supplied by this nerve. This can be used to measure the velocity of transmission which is typically slowed in carpal tunnel syndrome. EMG measures electrical activity in muscles. It can help differentiate between myopathy and neuropathy as cause of weakness.