Back Pain, Hip And
Knee Injuries
Lumbar back
pain is a common presentation to the Emergency Department, and can be very
challenging to manage. Patients may arrive at the Emergency Department with an
agenda that includes hospital admission for analgesia and rehabilitation. This
is not practical or desirable: after exclusion of significant pathology, early
mobilisation is the most effective treatment. Back pain may also be caused by
hip disease and retroperitoneal organs, e.g. aorta, pancreas.
Red flags
There are
four conditions that must not be missed.
1. Abdominal aortic
aneurysm (Chapter 19).
2. Malignancy.
3. Epidural abscess or
haematoma.
4. Large prolapsed disc
causing neurological deficit or cauda equina syndrome.
Therefore
any history and examination must document the following.
•
Age, back pain history, history of malignancy.
•
Pain at rest, pain wakes at night.
•
History of trauma, fever, intravenous drug use, anticoagulation.
•
Straight leg raising, angle, crossed leg raise.
•
Power at each joint (flexion, extension).
•
Reflexes: knee, ankle, plantar.
• Incontinence, perineal anaesthesia, reduced anal tone (implies possible
cauda equina syndrome).
Crossed
straight leg raising: lifting the unaffected leg reproduces pain in the
other leg. This is a very sensitive indicator of nerve root irritation, e.g.
from a prolapsed disc.
If there are
no abnormalities and the patient is otherwise well, the diagnosis is likely to
be mechanical back pain.
Investigations
Investigations
are rarely necessary if no red flag symptoms. MRI is the gold standard for
investigating spinal neurological problems. Urgent MRI scanning is indicated if
cauda equina is suspected. Lumbar spine X-ray (70 CXR) is only indicated with a
history of trauma or if malignancy is suspected.
Management
A positive
but firm attitude to encourage mobilisation may be necessary: Emergency
Department nursing staff are particularly skilled at this.
The
combination of an NSAID (e.g. ketorolac) and paraceta- mol/codeine-based
analgesia is a good starting point. Diazepam acts as a muscle relaxant if there
is significant spasm, but should only be given for a couple of days.
Hip and knee injury
The hip is
an inherently stable joint, which requires substantial energy to disrupt. The
knee’s stability depends on muscles, tendons, ligaments and cartilage, all of
which are vulnerable to injury. Osteoporotic bone is vulnerable to low-energy
injuries, i.e. ‘fragility fractures’ such as fractured neck of femur (#NoF).
Examination
Look Assess gait and inspect
for joint swelling or asymmetry. Look for shortening and external rotation
(#NoF) or flexion and internal rotation (dislocation of hip). Swelling of the
knee joint may be due to a joint effusion. Acute traumatic effusion occurs as a
result of bleeding from bony or ligamentous injury.
Feel Areas of tenderness may
indicate fracture, e.g. patella, head of fibula. Knee effusion is detected by
pushing the patella down so it makes contact with the anterior surface of the
femoral condyle – ‘patellar tap’.
Move Assess all hip
movements. Internal/external rotation at the hip is a sensitive test for
fractures. Assess range of movement of knee, specifically for pain or
instability (ligament injury) or locking/ unlocking (meniscus tear/loose body).
• Knee ligamentous stability: ACL, PCL, LCL, MCL (anterior and posterior
cruciate, lateral and medial collateral ligaments).
• Knee meniscal stability: Apley’s test.
• Patellar stability: apprehension test.
Neurovascular examination
Knee
dislocation damages the popliteal artery, which always needs expert
vascular assessment. The common peroneal nerve is at risk in lateral knee
injuries: test for dorsiflexion of foot and sensation over dorsum of foot.
Investigations
Bedside investigations
• Blood glucose, urine dipstick, ECG in patients with falls.
Laboratory investigations
• FBC and group and save indicated in all patients with pelvic or femur
fractures, as bleeding is often underestimated.
Imaging
• In frail elderly patients, even low amounts of energy can cause
fractures. All possible hip fractures should have an X-ray of the pelvis and
lateral hip. The pelvis and pubic rami are brittle ring structures, and like a
‘Polo’ ® mint, they can never be broken in one place only.
• The Ottawa knee rules prevent unnecessary knee X-rays.
• CT is useful for pelvic and tibial plateau fractures.
• MRI is the gold standard for the diagnosis of knee injuries and occult
hip fractures.
Treatment
Lower limb
fractures are painful. Intravenous opiates are often necessary. A femoral nerve
block gives effective analgesia for femoral fractures at/below the trochanter.
Femoral shaft fracture requires a traction splint.
Knee
A tense,
painful knee haemoarthosis should be aspirated. This also allows examination of
cruciate function, reduces intra-articular adhesions, or confirms haemarthrosis
vs. blood-stained effusion. By putting the aspirate into a bowl, fat globules
floating on the surface will be seen if there is a fracture.
Most
patients with isolated knee injuries will be able to go home in a knee brace or
a Robert Jones bandage (a wool and crepe bandage built up to support the
extended knee) with outpatient clinic follow-up.
Hip and femur
Fractured
neck of femur is common in the elderly and requires operative fixation.
Consider possible causes for falling (Chapter 29).
A patient
who has a clinically suspected fractured neck of femur but normal X-rays needs
admission and further investigation. These patients often have fractured pubic
rami, or impacted fractures seen on further imaging, e.g. MR.
