Femoral neck malunion: Definition, Uses, and Clinical Overview

Posted on February 27, 2026 | by drhip

Femoral neck malunion Introduction (What it is)

Femoral neck malunion means a femoral neck fracture has healed, but in a misaligned position.
It can change hip mechanics and contribute to pain, stiffness, or altered walking.
The term is commonly used in orthopedic clinics and radiology reports after hip fracture healing.
It helps clinicians describe alignment, anticipate symptoms, and discuss treatment options.

Why Femoral neck malunion used (Purpose / benefits)

Femoral neck malunion is not a treatment or device. It is a clinical diagnosis and descriptive term used to explain why a hip may function differently after a fracture has healed.

The purpose of identifying and naming Femoral neck malunion is to:

Clarify the cause of symptoms after a healed femoral neck fracture, such as persistent groin pain, limp, reduced range of motion, or weakness.
Describe the mechanics of the hip when the femoral neck has healed in varus/valgus (angled), rotated, or shortened alignment.
Guide further evaluation by indicating when additional imaging or functional assessment may be useful.
Support treatment planning by helping clinicians compare non-surgical options versus procedures that address alignment or joint damage.
Improve communication among orthopedic surgeons, sports medicine clinicians, physical therapists, and radiologists by using a shared, specific label.

In general terms, the “problem it solves” is explanatory and planning-focused: it links a prior fracture to current hip mechanics and symptoms, and it frames what goals (pain reduction, mobility, stability, function) are realistic to pursue. How Femoral neck malunion is handled varies by clinician and case.

Indications (When orthopedic clinicians use it)

Orthopedic clinicians commonly use the term Femoral neck malunion in scenarios such as:

Persistent hip or groin pain after a femoral neck fracture has “healed”
Ongoing limp, leg-length difference sensation, or reduced endurance with walking
Loss of hip range of motion, especially flexion and internal rotation
Mechanical symptoms (catching, pinching) that raise concern for impingement-type mechanics
Follow-up visits after internal fixation (pins/screws) where alignment is being assessed
Preoperative planning when considering corrective bone procedures or hip replacement
Imaging reports noting altered neck-shaft angle, femoral offset changes, or healed displacement
Post-traumatic hip arthritis evaluation where prior fracture alignment may be contributing

Contraindications / when it’s NOT ideal

Because Femoral neck malunion is a diagnostic description, “contraindications” most often relate to situations where the label may be incomplete, premature, or not the primary issue.

Situations where it may be not ideal to focus on malunion as the explanation (or where another diagnosis/approach may be more appropriate) include:

Acute (new) femoral neck fracture that has not yet healed (malunion refers to healed alignment)
Nonunion (failure to heal), where the problem is lack of bone healing rather than healed malalignment
Avascular necrosis (AVN) of the femoral head as the dominant cause of symptoms, even if mild malalignment is present
Active infection around the hip joint or prior hardware, where infection management takes priority
Primary hip osteoarthritis unrelated to fracture alignment, when imaging and clinical history point away from the prior fracture as the driver
Severe medical frailty or limited functional goals where extensive reconstruction may not match overall health context (management choices vary by clinician and case)
Pain sources outside the hip joint, such as lumbar spine or sacroiliac pathology, when the hip alignment change is incidental

How it works (Mechanism / physiology)

Femoral neck malunion affects the hip through biomechanics rather than a medication-like mechanism. There is no “onset” in the way a drug has onset; the effects typically relate to how the bone healed and how the hip is loaded during daily activities.

Key anatomy involved

Femoral neck: the short bony bridge between the femoral head and the femoral shaft
Femoral head: the “ball” of the ball-and-socket hip joint
Acetabulum: the pelvic “socket”
Articular cartilage and labrum: tissues that support smooth motion and joint stability
Hip abductors (e.g., gluteus medius): muscles that stabilize the pelvis during walking
Capsule and ligaments: soft tissues contributing to stability and motion limits

Biomechanical principles

When a femoral neck fracture heals in a malaligned position, it can change:

Neck-shaft angle (varus or valgus healing):
Varus alignment generally means the neck-shaft angle is reduced, which may shorten the limb and alter abductor leverage.
Valgus alignment means the angle is increased, potentially changing hip offset and joint loading patterns.
Femoral offset (the lateral distance that affects abductor tension and joint forces): changes may contribute to limp, fatigue, or altered gait.
Rotation (torsion): healed rotational differences can change hip motion arcs and may contribute to impingement-like symptoms.
Leg length: shortening across the fracture site can create functional asymmetry and compensatory mechanics.
Joint contact pressures: altered alignment can shift load distribution across cartilage and labrum, which may contribute to wear patterns over time.

Reversibility and time course

The malaligned bony shape is generally not reversible without a procedure that changes bone alignment or replaces the joint surface.
Symptoms can fluctuate with activity level, muscle conditioning, and coexisting joint or tendon issues.
Long-term effects vary widely by the degree and type of malunion, joint cartilage status, and individual activity demands.

Femoral neck malunion Procedure overview (How it’s applied)

Femoral neck malunion is not itself a procedure. Clinicians “apply” the concept by diagnosing it and using it to structure evaluation and decision-making. A typical high-level workflow may include:

Evaluation / exam – Review of the original injury and treatment (for example, fracture pattern and whether screws or other fixation were used) – Symptom review: pain location (often groin or lateral hip), limp, stiffness, instability sensations, functional limitations – Physical exam focused on hip range of motion, gait, strength (especially abductors), and provocative maneuvers that may suggest impingement mechanics
Preparation (diagnostic planning) – Selection of imaging based on the clinical question and prior studies – Consideration of other potential pain sources (lumbar spine, bursitis/tendinopathy, hernia, pelvic causes)
Intervention / testing – Plain radiographs (X-rays) are commonly used to assess healed alignment, neck-shaft angle, hardware position, and arthritis features. – CT may be used to better define rotational alignment or complex bony anatomy. – MRI may be considered when soft tissue, cartilage, labrum, or femoral head vitality (e.g., concern for AVN) needs assessment. Utility varies by clinician and case, and prior hardware can affect imaging quality.
Immediate checks (clinical interpretation) – Correlate imaging findings with symptoms and exam findings, since some alignment changes can be present with minimal symptoms. – Identify red flags or competing diagnoses (for example, nonunion or femoral head collapse patterns).
Follow-up – Monitoring of symptoms and function over time – If a procedure is considered, planning typically focuses on whether the goal is alignment correction (bone-preserving options) or joint surface replacement (arthroplasty options), depending on joint condition and patient factors. Specific choices vary by clinician and case.

Types / variations

Femoral neck malunion can be described in several overlapping ways. These descriptors help clinicians understand mechanics and select evaluation tools.

By alignment direction

Varus malunion: healed with a decreased neck-shaft angle; may be associated with shortening and altered abductor mechanics.
Valgus malunion: healed with an increased neck-shaft angle; may shift load patterns and change offset.
Rotational malunion: healed with internal or external rotational difference that can change gait and hip motion arcs.

By structural change

Shortening malunion: loss of length across the femoral neck leading to leg-length discrepancy or reduced offset.
Translation/displacement malunion: healed with residual sideways shift of fragments, altering hip geometry.

By clinical presentation

Asymptomatic or minimally symptomatic malunion: alignment difference is present on imaging but function is acceptable.
Symptomatic malunion: pain, limp, stiffness, weakness, or mechanical symptoms correlate with the healed deformity.
Malunion with secondary joint changes: coexists with cartilage wear, labral injury, femoroacetabular impingement-like mechanics, or post-traumatic arthritis features.

By context of the original fracture management

Post-fixation malunion: after screws/pins/other internal fixation, the bone heals but alignment is not anatomic.
Post-nonoperative malunion: after a fracture treated without surgery, alignment may heal in a suboptimal position (appropriateness varies by fracture type and patient factors).

Pros and cons

Because Femoral neck malunion is a diagnosis rather than a single treatment, the practical “pros and cons” relate to recognizing it clearly and the typical management pathways that may follow.

Pros

Helps explain persistent symptoms after a fracture that is technically “healed”
Provides a biomechanical framework for gait changes, weakness, and motion limitations
Supports clearer communication across clinicians and imaging reports
Guides targeted imaging choices (e.g., CT for rotation, MRI for femoral head concerns)
Can clarify whether goals are bone-preserving alignment correction versus joint replacement planning
Encourages evaluation of related issues (offset, leg length, abductor function), not only pain location

Cons

Imaging-defined malalignment does not always match symptom severity, so over-attribution is possible
Often overlaps with other post-fracture problems (AVN, arthritis, nonunion history), complicating interpretation
The term does not specify a single “best” next step; management varies by clinician and case
Correcting the underlying bony alignment, when pursued, can involve complex decision-making and trade-offs
Coexisting hardware can limit some imaging clarity and may influence planning
Functional impact can depend heavily on individual anatomy, activity, and rehabilitation progress

Aftercare & longevity

Aftercare and longevity considerations depend on whether Femoral neck malunion is being monitored, treated with rehabilitation-focused care, or addressed with a procedure. Outcomes are influenced by multiple factors rather than a single timeline.

Key factors that commonly affect longer-term function include:

Severity and type of malunion: varus/valgus angle change, rotation, and shortening can affect mechanics differently.
Condition of the femoral head and cartilage: if there is AVN or substantial cartilage wear, symptoms and durability of non-replacement options may differ.
Muscle strength and movement patterns: abductor weakness and compensations can amplify limp and fatigue.
Rehabilitation participation and follow-up: consistency with supervised therapy plans and reassessment can influence functional gains. Specific protocols vary by clinician and case.
Weight-bearing status (when a procedure has been performed): restrictions and progression are individualized, often based on fixation stability and healing assessment.
Comorbidities: bone density, smoking status, metabolic health, and inflammatory conditions can affect bone and joint health in general.
Hardware considerations: retained screws or other implants may be asymptomatic or may be part of ongoing assessment; whether they matter varies by clinician and case.
Activity demands: occupational lifting, high-impact sports, or repetitive twisting can influence symptoms and tolerance.

“Longevity” may refer to how long the hip remains functional without progression of pain or arthritis changes. That course is variable and depends on alignment, joint status, and overall health context.

Alternatives / comparisons

Femoral neck malunion is one possible explanation for post-fracture hip symptoms, but clinicians often compare it with other diagnoses and management approaches.

Observation/monitoring vs active intervention

Observation/monitoring may be reasonable when symptoms are mild and function is acceptable, especially if imaging shows a stable healed fracture and no concerning joint changes. Follow-up cadence varies by clinician and case.
Active intervention may be considered when pain, limp, or functional limits persist and correlate with the deformity or secondary joint damage.

Rehabilitation-focused care vs procedural approaches

Physical therapy and gait/strength retraining can help address compensations, improve hip and core strength, and optimize movement patterns, even when bone shape is unchanged.
Procedural options (broadly) may aim to:
Correct alignment (bone-preserving strategies such as osteotomy in selected contexts), or
Address joint degeneration (hip arthroplasty options when arthritis or femoral head viability issues dominate).
Selection depends on joint condition, age, bone quality, deformity pattern, and goals; it varies by clinician and case.

Imaging comparisons

X-ray: first-line for bone alignment, hardware, and arthritis features.
CT: helpful when rotational alignment and 3D bony anatomy need clearer definition.
MRI: helpful for soft tissues and femoral head concerns, but can be limited by metal artifact and depends on imaging protocols and hardware type.

Comparison with related post-fracture diagnoses

Nonunion: the fracture has not healed; pain may be more directly linked to instability at the fracture site.
Avascular necrosis: femoral head blood supply compromise can lead to collapse and arthritis-like pain patterns.
Primary osteoarthritis: degenerative joint disease not primarily driven by fracture alignment.

In practice, clinicians often consider more than one factor at once (for example, a mild malunion plus early arthritis), and the “main driver” of symptoms can differ between individuals.

Femoral neck malunion Common questions (FAQ)

Q: Is Femoral neck malunion always painful?
No. Some people have a malunion visible on imaging but minimal symptoms. Pain tends to be more likely when malalignment meaningfully alters mechanics, when there is secondary cartilage/labrum involvement, or when other issues (like AVN) coexist.

Q: What does Femoral neck malunion feel like?
Symptoms can include groin pain, lateral hip pain, stiffness, reduced hip motion, or a limp. Some people describe pinching with certain hip positions or fatigue with walking due to altered muscle leverage.

Q: How is Femoral neck malunion diagnosed?
Diagnosis usually combines history, physical exam, and imaging. X-rays assess healed alignment and joint changes, while CT or MRI may be used to clarify rotation, bone detail, or femoral head and soft tissue concerns when needed.

Q: Can Femoral neck malunion get worse over time?
The healed bone alignment itself typically does not “progress” without a new injury, but symptoms can change as activity level, strength, and joint surface health change. Some individuals develop increasing stiffness or arthritis-like symptoms over time, while others remain stable.

Q: What are common treatment options?
Options range from monitoring and rehabilitation-focused care to procedures that address alignment or joint damage. Which path is considered depends on symptoms, deformity pattern, cartilage health, and overall goals, and varies by clinician and case.

Q: How long does recovery take if a procedure is done?
Timelines vary widely depending on the type of procedure, bone quality, and rehabilitation plan. Follow-up often involves repeat assessment of function and, when relevant, imaging to evaluate healing or implant position.

Q: Will I need to limit weight-bearing?
If no procedure is performed, weight-bearing guidance depends on symptoms and clinician assessment. After surgery, weight-bearing status is typically individualized based on the reconstruction performed and healing considerations.

Q: Is it safe to drive or return to work with Femoral neck malunion?
Safety depends on pain control, reaction time, strength, and ability to perform emergency braking, as well as job demands. Decisions are individualized and often guided by functional testing and clinician recommendations rather than imaging alone.

Q: How much does evaluation or treatment cost?
Costs can vary substantially based on location, insurance coverage, imaging type (X-ray vs CT vs MRI), and whether surgery is involved. Implant and facility costs also vary by material and manufacturer, and by health system.

Q: Will screws or hardware need to be removed?
Not always. Hardware may remain without causing symptoms, but in some cases it can be part of pain evaluation or surgical planning. Whether removal is considered depends on symptoms, hardware position, bone healing, and overall treatment strategy, and varies by clinician and case.