The same few rules, repeated up and down the body
The first guide in this rung gave you the rules of the game: the phases of soft-tissue healing, why a tendinopathy is a failed-repair problem rather than a fire to be put out, and the difference between a sprain and a strain. This guide spends those rules. We walk the body region by region through the complaints that genuinely fill a musculoskeletal clinic — and you will notice the same handful of ideas resurfacing under different names. That repetition is the good news: you are not memorising seven unrelated diseases, you are applying one framework seven times.
Hold three threads in your hand as we go. First: load. Most of these problems are a mismatch between how much a tissue is asked to do and how much it can currently tolerate — too much, too soon, too often. Second: the diagnosis is usually clinical. A good story and a focused examination name most of these conditions; a scan often shows changes that are present in pain-free people too, which is why imaging confirms far less than patients expect. Third: rehab here restores function by progressively reloading the tissue, not by resting it into oblivion. Keep those three in view and the regional tour almost narrates itself.
Shoulder and elbow: tendons under a roof, tendons at an anchor
The shoulder is the body's most mobile joint, and it pays for that freedom with instability — it leans heavily on muscles and tendons to hold the ball centred in its shallow socket. Four of those muscles wrap the joint like a cuff; their tendons are the rotator cuff. When they become irritated, degenerate, or partly torn, the result is rotator cuff disease: pain reaching overhead, trouble sleeping on that side, a painful arc partway up as the arm lifts. The classic story is 'impingement' — the cuff pinched under the bony roof of the shoulder when the arm rises. That picture is useful but, honestly, oversimplified: much of the trouble is the tendon's own load-related degeneration, which is why simply 'making more room' surgically often disappoints, and why graded strengthening of the cuff and the shoulder-blade muscles is the mainstay.
Slide down to the elbow and the theme repeats at an anchor point. Where the forearm muscles take origin from the bony bumps of the elbow, repeated gripping and wrist loading can overload the tendon attachment. On the outer side that is lateral epicondylitis — 'tennis elbow', felt when you shake hands or lift a kettle; on the inner side, medial epicondylitis — 'golfer's elbow'. Note the '-itis' suffix promises inflammation, but the tissue under a microscope usually shows degeneration with little active inflammation, so the older name overstates the fire. The practical consequences are the same as the shoulder: settle the irritation, then load the tendon progressively, because the tendon adapts to load and wastes without it.
The low back: mechanical pain, and the nerve that sometimes complains
Low back pain is one of the most common reasons humans see any doctor at all, and the great majority of it is non-specific mechanical low back pain: pain that varies with posture and movement, eases with position change, and cannot be pinned to a single damaged structure. That word 'non-specific' frustrates patients, who expect a scan to point at the culprit. Here honesty matters most. Imaging of pain-free adults routinely shows bulging discs and 'degeneration', so a scan finding does not prove it is the source of pain — and early imaging in ordinary back pain can do harm by labelling normal age-related changes as damage. The reassuring core message is that most episodes settle, and that staying active beats bed rest.
Sometimes the pain is not in the back but shoots down a leg in a clean stripe, with numbness or weakness following the same path. That is radiculopathy — a spinal nerve root being compressed or irritated, often by a disc that bulges onto it. The leg symptoms follow the map of that one root, which is exactly what an examination, and if needed the electrodiagnostic study from the diagnostics rung, can localise. Most radiculopathy also improves over weeks to a few months without surgery. The genuine red flags — a sudden loss of bladder or bowel control, saddle numbness, rapidly progressing weakness — are rare but urgent, and are the reason a careful clinician always asks about them.
Hip and knee: when the joint surface itself wears
Move down to the big weight-bearing joints and the story changes from tendon to cartilage. Osteoarthritis of the hip and knee is the gradual wear of the smooth joint surface, with the bone underneath remodelling and the whole joint becoming stiff and achy. The hallmark is pain that worsens with use and eases with rest, morning stiffness that loosens within minutes, and a joint that creaks and slowly loses its range. A crucial honesty here: the amount of wear on a scan correlates poorly with how much it hurts — some people with badly worn joints have little pain, and some with mild changes have a lot. So osteoarthritis rehabilitation does not chase the X-ray; it targets function. The single most evidence-backed treatment is not a pill or an injection but exercise — strengthening the muscles around the joint and keeping it moving — alongside weight management, which lightens the load the joint carries every step.
Not all knee pain comes from worn cartilage, and the most common knee complaint in younger, active people is a good example. Patellofemoral pain is an ache around or behind the kneecap, worse going down stairs, squatting, or sitting with the knee bent for a long time (the 'cinema sign'). The kneecap is a sesamoid bone that glides in a groove as the knee bends; when the forces tracking it through that groove are unbalanced — often a matter of hip and thigh muscle control more than the knee itself — the joint surface gets irritated. The reassuring part of patellofemoral pain is that the structure is usually fine; it responds to graded strengthening of the hip and thigh and to load management, not to rest or bracing alone.
READING A REGION — the same five questions every time 1. WHERE & WHEN -> exact spot; with use, at rest, at night? 2. WHAT TISSUE -> tendon / cartilage / ligament / nerve / bone? 3. LOAD STORY -> a new spike? too much, too soon, too often? 4. RED FLAGS? -> fever, trauma, night pain, weakness, bladder/bowel 5. FUNCTION GOAL -> what can't they do that they need to do? Notice: imaging is NOT step 1. The story and the exam come first.
Ankle and foot: the rolled ankle and the morning-first-step heel
The most common acute injury in all of sport is the ankle sprain — the foot rolls inward, over-stretching or tearing the ligaments on the outside of the ankle. This is a ligament injury, a true sprain in the sense the first guide drew, and it follows the soft-tissue healing phases closely: a swollen, painful first few days, then the rebuilding and remodelling weeks. Early sensible loading and a return to movement beat prolonged immobilisation, captured in the modern POLICE principle — Protection, Optimal Loading, Ice, Compression, Elevation — which deliberately replaced the older 'rest it completely' advice. The honest catch is that ankle sprains recur: the under-appreciated reason is that the injury blunts the joint's position sense, so balance and proprioceptive retraining, not just waiting for the swelling to go, are what stop the next roll.
Finally, the heel. Plantar fasciitis is the classic 'first steps in the morning hurt' complaint: a sharp pain under the heel that is worst with the first few steps after rest and eases as the tissue warms up. The plantar fascia is a thick band along the sole that supports the arch; like the tendons above, the painful version is mostly degenerative load-related change rather than raging inflammation, despite the '-itis'. People fixate on the heel spur often seen on X-ray, but the spur is frequently present in pain-free feet and is not the cause. Plantar fasciitis is slow to settle — months, not weeks — and responds best to calf and fascia stretching, load management, supportive footwear, and patience, which is itself a hard prescription to deliver.
What ties the whole tour together
Step back and the regional map collapses into a few principles. Tendon problems — cuff, epicondyle, plantar fascia — are load-mismatch degeneration that improve with graded loading, not rest. Joint-surface problems — hip and knee osteoarthritis — are managed by strength, movement, and weight, not by chasing the X-ray. Ligament injuries — the ankle sprain — heal through predictable phases and need early sensible loading plus balance retraining to stop recurrence. And the back, more often than not, is non-specific pain that wants reassurance and activity, with a watchful eye for the nerve root and the rare red flag. The common thread, true at every level of the body, is that motion is medicine and graded load is the active ingredient.
Two limits to carry forward honestly. First, naming the region is the start, not the end: the same 'rotator cuff disease' label sits on a weekend gardener and a competitive swimmer whose needs, loads, and goals are utterly different, which is why function — not the diagnosis alone — drives the plan. Second, the tools that actually move the needle are mostly active and unglamorous: education, graded exercise, and load management. The passive add-ons many patients ask for — ultrasound, heat, electrical modalities — rest on a thin evidence base for these conditions and at best buy short-term comfort. The next guides in this rung pick up the genuinely useful interventional and sports tools, and how to judge when ultrasound at the bedside, like musculoskeletal ultrasound, truly adds something.