1. Is patient younger than 16 years
MRI Referral Flow Chart Sciatica Plain film lumbar spine XR is not indicated as it does not contribute to the management of leg pain
Is patient younger than 16 years
Yes No
Your patient may have unexpected pathology and paediatric referral is indicated
Does pain radiate below the knee and a genuine straight leg raise (SLR) sign is present?
(SLR test results in severe aggravation symptoms or LBP, not just hamstring tightness)
Does patient have motor deficit e.g. foot drop. NB absent ankle jerk is not motor deficit No
Yes
Forward to criteria for Acceptance GP Referrals MRI
Return to NHS Tayside MSK Guidelines
Return to NHS LBP Pathway
MRI not indicated No
Yes
Refer for urgent MRI and urgent surgical clinic review
On MRI request form, write ‘urgent’ and the name of the consultant your patient has been referred to
Has the patient has symptoms for more than 4 weeks? No
Yes
Refer for routine MRI. Surgical discussion at referrer’s discretion.
MRI request forms should state the side and dermatomal location of symptoms / signs so that informed correlation with imaging findings can be made. E.g. right side sciatica, L5 dermatomal pain/numbness. No motor signs ? R L5 nerve root entrapment
MRI not indicated. Continue with conservative management, as symptoms may improve spontaneously

2. Criteria for Acceptance of Direct GP Referrals for Lumbar Spine MRI
Routine referral
Sciatica
Patients over 16 with sciatica, defined as pain radiating below the knee, showing no improvement within 4 weeks of onset, with sensory deficit or genuine positive straight leg raise.
Spinal Claudication
Patients with symptoms suggesting spinal claudication (stenosis). (Pain, weakness or numbness in one or both legs, present on walking, eased by sitting or bending forward, lower limb circulation normal)
Urgent Referral
Patients with sciatica and a developing motor deficit should be referred simultaneously for an urgent MRI scan and a surgical opinion. This should be specified on the MRI referral form so that it will be expedited and result made available for the clinic appointment.
NB an absent ankle reflex in isolation is not a motor deficit
Clinical conditions excluded from pathway
Suspected acute cauda equina syndrome should be managed as emergency
Patients with Mechanical LBP should not be routinely referred as most do not require or benefit from MRI scanning
Return to NHS LBP Pathway
Return to NHS Tayside MSK Guidelines

3. MRI Criteria Knee (Barry Oliver Consultant Radiologist, Graeme Foubister Petros Boscainos and Richard Buckley Consultant Orthopaedic Surgeons)
MRI not indicated
Patients under 15 or over 60
Locked knee
symptoms are continuous, not momentary or intermittent
a locked knee lacks at least 15 degrees of extension and cannot flex to 90 degrees
(such patients need urgent orthopaedic referral with a view to arthroscopy – MRI is unnecessary and delays treatment)
Pseudolocking
(not to be confused with locking, this is momentary stiffness following a period of immobility – typically in obese people with patellofemoral OA)
Knee dislocation or other severe acute injury
(such patients are orthopaedic emergencies and should be dealt with by secondary care)
Any osteoarthritis (OA) on an x-ray
Obese patients with any clinical or radiographic evidence of OA
(OA is very common in obese people – MRI in knees with OA often shows meniscal damage that is not treatable by arthroscopy)
Any previous meniscal surgery
(post-operative menisci simulate meniscal tears on MRI – direct orthopaedic clinic referral is appropriate in such patients)
Active knee inflammatory arthritis, unless symptoms relate to a recent injury
Anterior knee pain
(usually due to patellofemoral OA, chondromalacia patellae or tendon problem which may benefit from physiotherapy)
MRI indicated
A knee XR must have been obtained within 6 months of MRI request
Suspected meniscal tear
previous injury with
medial joint line tenderness and pain worsened by external rotation at 90 degrees knee flexion Or
lateral joint line tenderness and pain worsened by internal rotation at 90 degrees knee flexion
Instability
previous injury
subsequently, knee gives way during rotation or pivoting
Forward to MRI knee flowchart
Return to Knee Pain Information
Return to NHS Tayside MSK Guidelines

4. Flowchart For Knee MRI Direct Access
Is the patient aged years?
No patient > 60 will be accepted for knee MRI NO
Consider Children's Orthopaedic or Paediatric clinic referral for children.
OA is very common in those over 60 years – consider trial of symptomatic treatment.
YES
YES
Is the knee locked?
Is this a severe acute injury?
Urgent orthopaedic referral is indicated.
MRI may delay treatment NO
A knee XR must have been obtained within 6 months of MRI request
Is there: Any evidence of OA on x-ray?
Pseudolocking?
Predominantly anterior knee pain?
YES
OA is likely cause of symptoms.
Consider symptomatic treatment or physiotherapy. NO
YES
Rheumatology clinic referral may be more appropriate in the absence of a relevant injury.
Is there an active inflammatory
arthritis and no recent injury? NO
YES
Has there been previous meniscal surgery?
Consider Orthopaedic referral. NO
YES
Do clinical features indicate:
instability or meniscal tear
MRI referral may be beneficial to this patient NO
Return to Knee Pain Information
Return to NHS Tayside MSK Guidelines
Consider symptomatic treatment or physiotherapy