McKENZIE METHOD · EXTREMITY · 13 min read
MDT Isn’t Just for Back Pain: Mechanical Diagnosis of the Shoulder, Hip, and Knee
The McKenzie Method is best known for spine care — but its mechanical classification system applies equally to the shoulder, hip, and knee. Understanding the difference between derangement and dysfunction at these joints can explain why some patients plateau, and what to do about it.
By Meghan McConville Montano, MSPT, OCS, Cert. MDT · KinetiQ Spine & Sport PT
Think the McKenzie Method is just for back pain? Think again. Its movement-based approach can also be used to assess and treat problems affecting the shoulders, hips, knees, and other joints. MDT has an extensive evidence base in lumbar and cervical spine care, where much of the research has focused. But the mechanical principles at the heart of MDT are not limited to the spine—they can also help clinicians understand how movement and repeated loading influence symptoms in other areas of the body.
Extremity conditions — shoulder, hip, and knee in particular — are frequently mechanical in nature, meaning they arise from how a joint is loaded, positioned, and moved over time. And like spinal conditions, many of these problems can be classified into distinct mechanical syndromes — each with different clinical features, different treatment implications, and a different prognosis.
Two of those syndromes are especially relevant for patients with persistent extremity pain: derangement and dysfunction. Understanding the difference between them is one of the most practically useful things a patient can take away from a mechanical evaluation — because it explains not just what’s wrong, but why treatment needs to work the way it does.
Derangement vs. Dysfunction: Two Different Mechanical Problems
In the MDT classification system, derangement and dysfunction are distinct syndromes with different underlying mechanisms, different symptom behaviors, and different treatment approaches. Both occur in the spine and in peripheral joints.
Derangement Syndrome
Derangement involves an internal mechanical disruption within a joint — most commonly involving the articular surfaces, disc, or intra-articular structures — that produces a consistent, directionally-responsive symptom pattern. The hallmark of derangement is that symptoms change rapidly and significantly with repeated movement in a specific direction.
In derangement, there is typically a direction of movement that causes symptoms to reduce, centralize, or abolish — and an opposite direction that causes them to worsen or spread. When a clinician identifies this directional preference during assessment, treatment is built around it. Derangement responds relatively quickly when the right direction is found, and patients can often drive their own recovery with a targeted home program.
Dysfunction Syndrome
Dysfunction involves pain that arises from mechanically impaired tissue — typically shortened, scarred, or adaptively thickened structures that have lost their normal extensibility. The hallmark of dysfunction is pain that occurs consistently and only at end-range, during the movement that stresses the impaired tissue.
Unlike derangement, dysfunction does not produce rapidly changing symptoms. The pain is predictable — it is always present at a specific end-range, never centralizes or abolishes acutely, and does not worsen with repeated loading in the way derangement might. Treatment involves a progressive, sustained loading strategy in the direction that engages the restricted tissue — essentially a structured remodeling process. It takes longer than derangement treatment, but when correctly identified and consistently applied, it produces lasting improvement.
Why the Distinction Matters for Treatment
A patient with dysfunction who is given derangement-style repeated loading — or vice versa — will not improve, and may worsen. Correct classification is the foundation of correct treatment. This is why a thorough initial evaluation is essential, and why generic exercise protocols frequently fail patients with mechanical extremity conditions.
The Shoulder: Derangement and Dysfunction in the Most Mobile Joint
The shoulder is the most mobile joint in the body, which makes it both capable and vulnerable. Many shoulder conditions are labeled as rotator cuff tendinopathy, impingement, or adhesive capsulitis — diagnoses that describe tissue location and irritation but say relatively little about the mechanical behavior of the joint. MDT classification goes deeper.
Shoulder Derangement
A mechanical derangement of the shoulder involves an internal disruption — typically within the glenohumeral joint — that causes pain and often a loss of range of motion in a directionally consistent pattern. The defining feature is that symptoms and motion loss are not static: they shift predictably with repeated movement.
Common presentations include:
- Pain that worsens in one rotation arc (e.g., internal rotation behind the back) but diminishes with the opposite direction (external rotation in abduction)
- Referred pain into the upper arm or lateral deltoid that centralizes toward the shoulder joint with a specific repeated loading direction
- A range of motion loss that improves measurably over the course of repeated movement testing in the preferred direction — a rapid change that distinguishes derangement from other presentations
- Acute onset following a specific movement, position, or loading event, with symptoms that have remained present since
When a directional preference is identified in a shoulder derangement, treatment is built around that direction — not a standard rotator cuff program. A patient who centralizes their shoulder pain with repeated end-range external rotation will work with a very different loading strategy than one whose preference is for horizontal flexion or inferior glide.
Shoulder Dysfunction
Shoulder dysfunction is common — and commonly misdiagnosed as ongoing impingement or “tightness” that just needs more stretching. It typically develops following a derangement that was incompletely resolved, a period of immobilization, post-surgical healing, or gradual disuse. The result is adaptively shortened capsular or periarticular tissue that produces consistent pain at end-range in one or more directions.
The clinical picture is distinct from derangement:
- Pain occurs consistently and only at end-range of the restricted movement — never mid-range, and not before end-range is reached
- There is no rapid change in symptoms with repeated movement — the pain is predictable and does not centralize or abolish during the assessment
- Range of motion loss is consistent and does not improve acutely with repeated loading — distinguishing it from derangement, where range often improves quickly
- Frozen shoulder (adhesive capsulitis) is the archetypal shoulder dysfunction — presenting with a capsular pattern of loss and end-range pain that requires progressive, sustained loading over months to remodel the restricted capsule.
Patients with shoulder dysfunction who have been doing generic range-of-motion exercises without a structured, progressive end-range loading strategy are often working in the right neighborhood but without the specificity needed to drive tissue remodeling. MDT assessment identifies which direction is restricted, what the end-range behavior looks like, and how to structure a loading program that progressively challenges the restriction over time.
Shoulder dysfunction and derangement can look similar from the outside — both involve pain and restricted motion. What distinguishes them is how the joint responds to repeated loading. That response is only visible through systematic assessment.
The Hip: An Underrecognized Site of Mechanical Classification
Hip pain is frequently attributed to bursitis, labral pathology, arthritis, or hip flexor tightness — and while all of these can be legitimate contributors, many patients with hip pain have a mechanical component that hasn’t been assessed. The hip is a deep ball-and-socket joint capable of both derangement and dysfunction, often presenting in ways that are easily confused with each other or with lumbar referral.
Hip Derangement
Hip derangement involves an intra-articular disruption that produces directionally-responsive symptoms — often with referred pain into the groin, anterior thigh, or knee that changes location or intensity with repeated hip movement. The referred pain pattern is an important clue: when symptoms move closer to the joint (centralize) with loading in one direction, that is a mechanical derangement response with strong treatment implications.
Common derangement presentations at the hip include:
- Groin-dominant pain with weight-bearing in specific arcs — particularly flexion with internal rotation — that improves with unloading or with movement in the opposite direction
- Referred pain into the anterior thigh or knee that centralizes toward the hip joint with repeated movement testing in a specific direction
- A variable loss of hip range of motion that improves measurably with repeated loading in the preferred direction during the assessment session
- Position-dependent symptoms that improve with unloading (lying down) and worsen quickly with specific loading postures — consistent with a moveable intra-articular component
Hip Dysfunction
Hip dysfunction is particularly common in patients with a history of hip derangement that was not fully resolved, those who have undergone hip surgery (labral repair, total hip arthroplasty), and older adults with longstanding osteoarthritis-related capsular tightening. It presents as consistent end-range pain in one or more directions of hip movement, without the rapid symptom fluctuation seen in derangement.
The clinical features that distinguish hip dysfunction include:
- End-range pain that is predictable and direction-specific — for example, consistent pain at end-range hip extension or internal rotation, present every time that position is reached
- No centralization or rapid symptom change during repeated movement testing — the pain is consistent, not variable
- Gradual onset without a specific precipitating event, often developing over months or years of restricted movement patterns
- A capsular pattern of restriction in more advanced cases — a characteristic combination of motion loss that reflects capsular rather than intra-articular involvement
For patients with hip dysfunction, treatment is not about finding a preferred direction — it’s about identifying the restricted direction and loading it progressively at end-range to drive tissue remodeling. This is a longer process than derangement treatment, but it is specific and goal-directed in a way that generic hip strengthening is not.
Many patients told they have “tight hip flexors” or “early arthritis” have never had their hip classified mechanically. The classification determines whether they need derangement loading, dysfunction remodeling, or a combination of both.
The Knee: Derangement and Dysfunction with High Clinical Overlap
The knee is one of the most common sites of mechanical classification in extremity MDT, and one where derangement and dysfunction frequently coexist — particularly following injury, surgery, or prolonged pain-limited movement. Understanding which syndrome is primary — or whether both are present — is essential for directing treatment appropriately.
Knee Derangement
Knee derangement in the MDT sense refers to an internal mechanical disruption of the tibiofemoral or patellofemoral joint that produces a consistent, directionally-responsive symptom pattern. This is distinct from — though may coexist with — structural pathology like meniscal tears or chondral lesions.
Patients with mechanical knee derangement often present with:
- Pain and/or a block at end-range extension or flexion that is variable — sometimes present, sometimes not — suggesting a moveable internal component
- A loss of full extension that improves measurably with repeated extension loading during the assessment — a classic derangement response
- Locking or catching sensations that resolve with specific movement but recur with certain activities
- Pain that shifts location or intensity with repeated flexion or extension testing — a hallmark of mechanical, rather than purely structural, origin
The loss of full knee extension is a particularly important derangement finding. Full extension is essential for normal gait mechanics, and patients who walk with even a slight flexion posture — often without realizing it — frequently develop secondary hip, low back, or patellofemoral symptoms over time. When repeated end-range extension loading progressively restores range of motion and reduces pain during the assessment, that is a directional preference finding with immediate, practical treatment implications.
Knee Dysfunction
Knee dysfunction is especially prevalent in patients with a history of ACL reconstruction, meniscal repair, total knee arthroplasty, or prolonged knee pain with movement avoidance. It involves adaptively shortened periarticular tissue that produces consistent end-range pain during the movement that stresses it — most commonly at end-range flexion or extension.
Key features that suggest knee dysfunction rather than — or in addition to — derangement include:
- Consistent end-range pain in one direction that does not vary session to session and does not improve acutely with repeated loading
- A persistent range of motion deficit that has been present for weeks or months and has not changed with standard rehabilitation
- Pain specifically with the final degrees of motion — not mid-range, not with light loading — emerging only as the tissue’s physiological end-range is approached
- Post-surgical presentation where scar tissue or capsular tightening has limited motion recovery beyond what strengthening can address
For patients post-ACL reconstruction or TKA who have “plateaued” in their rehabilitation — achieving baseline strength but not full motion or pain-free function — knee dysfunction is a common and underrecognized contributor. A structured end-range loading program targeting the restricted direction can produce motion gains that strengthening alone cannot.
The Common Thread: Classification Before Treatment
Whether the joint is the shoulder, hip, or knee — and whether the syndrome is derangement, dysfunction, or a combination — the MDT approach follows the same foundational logic: classify first, treat second.
Without classification, treatment is necessarily generic. A patient might receive a rotator cuff strengthening program when what they need is end-range capsular loading for a frozen shoulder. Or they might receive hip flexor stretching when what they need is directional derangement loading. Generic programs occasionally produce the right result by accident, but they cannot be relied upon to do so.
With classification, treatment becomes precise:
- Derangement: load in the direction of preference, repeatedly, with the goal of symptom abolition and rapid return of function
- Dysfunction: load progressively at end-range in the restricted direction, consistently, with the goal of tissue remodeling over weeks to months
- Mixed presentation: address derangement first to establish a stable baseline, then address residual dysfunction with targeted end-range work
The same diagnosis — shoulder pain, hip pain, knee pain — can represent two entirely different mechanical problems requiring two entirely different treatment approaches. Classification is what makes the difference visible.
For Patients Who Haven’t Found Answers
If you’ve been dealing with shoulder, hip, or knee pain and have moved through rest, generic exercise, or passive treatments without lasting relief, a mechanical assessment may offer a different frame. The question it answers isn’t just “what is wrong” — it’s “what kind of mechanical problem is this, and what does that mean for how it needs to be treated?”
At KinetiQ Spine & Sport PT, extremity conditions are assessed using the same systematic, evidence-based approach applied to spine conditions — with a full 60 minutes, one-on-one, to identify the mechanical syndrome driving the presentation and build a treatment plan around it.
Shoulder, hip, or knee pain that hasn’t responded to treatment?
A mechanical classification may reveal what’s been missed. KinetiQ offers 60-minute initial evaluations with no aides and no generic protocols — just focused clinical assessment built around your specific presentation. Reach out to schedule or ask a question before booking.