Does the color of the knee changes with the walking?
Is there increased pain on walking or standing?
Was an MRI of the lower back, NCV or colored doppler study done?
Any past significant medical or surgical history or family history?
An abnormal EMG definitely points to nerves. In a young the most common diagnosis considered is a pinched nerve. This can be due to;
1) Herniated/degenerated disc in back
2) Lumbar spondylosis; bone spurs in the back vertebrae pressing on the nerves.
A nerve conduction velocity study (NCV) would be required which further reinforces the neurological involvement, if comes out to be abnormal. A resting knee color change, not aggravating by walking and his young age group rule out the arterial disease, though a colored doppler study would be prudent, especially, if one is smoker.
Please feel free for your follow up questions.
The criteria for the conservative (medical) or surgical treatment would be dependent on;
1) severity of the symptoms manifestations
2) investigative finding of NCV, EMG and MRI
The initial conservative trial can be given, which entails;
1) Back care in the activities of daily living,
a) Avoid activities which increases the symptoms.
b) Rest intermittently
c) Avoid bending at 90 degrees
d) Pushing and pulling should be avoided till pain subsides
f) Avoid prolonged sitting and standing
g) Avoid sitting or sleeping on floor
2) Anti-inflammatory analgesics like ibuprofen and muscle relaxants
3) Local analgesic gels or sprays / ointment if needed
4) Hot fomentation
5) Electrotherapy like trans cutaneous electrical nerve stimulation: done by physical therapist. Other thing are ice packs, heating pads, electrical stimulation, phonophoresis, iontophoresis, relaxation, and biofeedback.
6) Good supervised physiotherapy: The exercises consist of abdominal bracing, modified sit-ups, double-knee-to-chest or low back stretches, seat lifts, mountain and sag exercises, knee-to-elbow exercises, hamstring stretches, extension exercises, and extension flexibility exercises. Swimming exercises (pool exercises) are best for back pain. Initial stretching and later strengthening exercises are taught.
7) Lumbosacral corset or support or brace
8) If obese or over weight, reduce weight for long term benefit.
9) Epidural steroid shots
10) Surgery is usually last resort, when the above conservative measures fail. One can start the following exercises;
1) Straight leg raising: Lie on the bed with your back and remain in a relaxed position. Slowly raise one of your legs upward and keep it as straight as possible. Count up to ten, and slowly bring down the leg. Do the same with the other leg. Repeat this exercise ten times.
2) Curl ups; lie on the back with knees bent, fold arms across the chest, tilt the pelvis to flatten the back, and curl-up lifting the head and shoulders from the bed / couch. Hold for ten seconds, then slowly lower to starting position. As strength builds, aim to complete one sets of ten curls. The exercise should be done twice a day (both the sets).
This is a slide show for the exercises (you can pick up your own set, which suits you);
You can consult following specialists (apart from your GP);
c) MD in Physical medicine and rehabilitation