10.1 Hip Disorders: Osteoarthritis, Labral Tears & Femoroacetabular Impingement

10.1 Hip Disorders: Osteoarthritis, Labral Tears & Femoroacetabular Impingement

[!NOTE] DHA Licensing Competency Focus: Musculoskeletal examination and rehabilitation of the hip joint represent a high-yield domain on the DHA Physiotherapist licensing examination. Candidates must master hip kinematics (including structural variations in inclination and torsion), correctly apply and interpret the Sutlive clinical prediction rule and Kellgren-Lawrence staging for hip osteoarthritis, calculate the biomechanical rationale of assistive device prescription, differentiate Cam versus Pincer femoroacetabular impingement, and accurately assign surgical approach-specific movement precautions following Total Hip Arthroplasty (THA).

The hip (acetabulofemoral) joint is a true multiaxial spheroidal (ball-and-socket) synovial joint engineered for both high-load transmission and multi-planar mobility. The stability of the hip is governed by its deep bony acetabulum, fibrocartilaginous labrum, robust capsular-ligamentous restraints (iliofemoral, pubofemoral, and ischiofemoral ligaments), and surrounding muscular envelope.

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1. Hip Joint Kinematics, Morphological Variations & Clinical Alignment

Capsular Pattern of the Hip

When the hip joint capsule undergoes uniform inflammatory contracture (such as in active osteoarthritis, adhesive capsulitis of the hip, or inflammatory arthropathy), joint range of motion (ROM) is restricted in a distinct non-random distribution:

• Cyriax Capsular Pattern: Marked gross limitation of Internal Rotation, accompanied by limitation of Flexion and Abduction, with slight limitation of Extension, and relative sparing of External Rotation.
• Kaltenborn / Maitland Pattern: Internal Rotation > Extension > Abduction > External Rotation (with flexion frequently restricted in end-stage degeneration).
• DHA Key Finding: A restriction disproportionately affecting internal rotation and flexion in an older adult is the hallmark physical exam sign of intra-articular hip pathology.

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|                         Hip Morphological Angles & Deviations                     |
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| 1. Angle of Inclination (Frontal Plane):                                          |
|    - Normal Adult: 125° (Range: 120° to 135°)                                     |
|    - Coxa Vara: < 120°  -> Bending moment/shear increases; limb shortened;        |
|                            abductor moment arm lengthened; predisposes to SCFE    |
|    - Coxa Valga: > 135° -> Compressive stress increases; limb lengthened;         |
|                            abductor moment arm shortened; predisposes to subluxation
+-----------------------------------------------------------------------------------+
| 2. Angle of Torsion (Transverse Plane):                                           |
|    - Normal Adult Anteversion: 8° to 15° (infant: ~30°-40°)                       |
|    - Excessive Anteversion: > 15°-20° -> In-toeing gait; IR >60°, ER restricted   |
|    - Retroversion: < 8°               -> Out-toeing gait; ER increased, IR <15°   |
|    - Assessment: Craig's Test (Trochanteric Prominence Angle Test)                |
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Structural Variations in the Frontal Plane: Angle of Inclination

The angle formed between the longitudinal axis of the femoral neck and the longitudinal axis of the femoral shaft in the frontal plane determines joint contact forces and abductor mechanics:

1. Coxa Vara (Angle < 120°):
   • Biomechanical Consequences: The femoral neck is oriented more horizontally. This increases the perpendicular moment arm of the hip abductor muscles ($MA_{abd}$), which technically reduces the muscular force required by the gluteus medius to balance the pelvis during single-leg stance. However, the horizontal orientation dramatically increases the bending moment and shear force across the femoral neck and epiphyseal plate.
   • Clinical Implications: Predisposes adolescent athletes to Slipped Capital Femoral Epiphysis (SCFE) and femoral neck stress fractures. Causes functional limb shortening and increases tension on the greater trochanter.
2. Coxa Valga (Angle > 135°):
   • Biomechanical Consequences: The femoral neck is oriented more vertically. This decreases the bending shear across the neck but substantially shortens the abductor muscle moment arm. Consequently, the gluteus medius must generate significantly higher muscular force to prevent pelvic drop during gait, elevating total compressive joint reaction force.
   • Clinical Implications: Decreases acetabular coverage of the superior femoral head, predisposing to superolateral subluxation, early joint incongruence, functional leg lengthening, and rapid muscle fatigue.

Structural Variations in the Transverse Plane: Femoral Torsion

The angle of torsion reflects the relative twist between the femoral neck axis and the transcondylar axis of the distal femoral condyles:

1. Excessive Femoral Anteversion (> 15°–20°):
   • The femoral head points anteriorly relative to the acetabulum. To seat the femoral head congruently within the socket during upright weight-bearing, the patient reflexively internally rotates the entire lower extremity.
   • Clinical Manifestation: Patient presents with an in-toeing (pigeon-toed) gait, toe-in foot posture, marked increase in passive internal rotation (frequently >60°), and prominent deficit in passive external rotation (often <20°–25°).
2. Femoral Retroversion (< 8°):
   • The femoral neck is twisted posteriorly relative to the femoral condyles.
   • Clinical Manifestation: The patient exhibits an out-toeing gait, marked restriction of passive internal rotation, and excessive passive external rotation (frequently >45°).
3. Craig's Test (Trochanteric Prominence Angle Test):
   • Technique: The patient is placed prone with the knee flexed to 90°. The clinician palpates the lateral aspect of the greater trochanter while passively rotating the hip through internal and external rotation.
   • Measurement: When the greater trochanter reaches its most prominent lateral position (indicating the femoral head and neck are aligned parallel to the examination table in the neutral transverse plane), the angle between the long axis of the vertical tibia and the vertical plumb line is measured using a standard goniometer.
   • Interpretation: An angle greater than 15°–20° indicates excessive anteversion; an angle less than 8° indicates retroversion.

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2. Hip Osteoarthritis (Coxarthrosis): Radiographic Staging & Clinical Prediction Rules

Hip osteoarthritis is a progressive degenerative disorder characterized by articular cartilage breakdown, subchondral sclerosis, osteophyte formation, and synovial fibrosis.

Kellgren-Lawrence (K-L) Radiographic Grading Scale

Sutlive Clinical Prediction Rule (CPR) for Hip Osteoarthritis

Sutlive et al. (2008) developed and validated a clinical prediction rule to identify patients with hip osteoarthritis without requiring immediate radiography. The cluster consists of 5 clinical examination variables:

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|                    Sutlive Diagnostic Cluster for Hip Osteoarthritis              |
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| 1. Self-reported squatting as an aggravating factor                               |
| 2. Active hip flexion causing lateral hip pain                                    |
| 3. Scour test with adduction causing lateral hip or groin pain                    |
| 4. Active hip extension causing pain                                              |
| 5. Passive hip internal rotation less than or equal to 25°                        |
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| Diagnostic Probability:                                                           |
|   - 3 of 5 positive: Positive Likelihood Ratio (+LR) = 5.2 (Moderate shift)       |
|   - 4 of 5 positive: Positive Likelihood Ratio (+LR) = 24.3 (Post-test prob ~91%) |
|   - 5 of 5 positive: Positive Likelihood Ratio (+LR) > 24.3 (Near certainty)      |
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Altman / American College of Rheumatology (ACR) Clinical Criteria: Hip pain plus either: (1) Hip internal rotation <15° along with hip flexion ≤115°; OR (2) Hip internal rotation ≥15° along with pain on internal rotation, morning stiffness ≤60 minutes, and age >50 years.

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3. Evidence-Based Conservative Management of Hip Osteoarthritis

Clinical practice guidelines strongly endorse multimodal conservative management combining manual therapy, targeted therapeutic exercise, weight control, and gait mechanics optimization.

Manual Therapy Interventions

• Long-Axis High-Grade Distraction Mobilization:
  • Biomechanical Objective: Separates the articular surfaces, expands intra-articular space, breaks capsular adhesions, stretches the contracted inferior and posterior capsule, and stimulates large-diameter mechanoreceptors for pain inhibition (gate control theory).
  • Dosage: Patient supine with hip in 30° flexion, 30° abduction, and slight external rotation (open-packed position). Therapist applies manual long-axis traction along the longitudinal axis of the femur (Maitland Grade III sustained or Grade IV oscillatory glides for 3–5 bouts of 30–60 seconds).
• Posterior and Inferior Joint Glides:
  • Inferior glides directly restore restricted hip flexion.
  • Posterior glides directly restore restricted hip internal rotation and flexion.

Strengthening & Neuromuscular Retraining

• Targeted Muscle Groups: Gluteus medius (stabilizes pelvis in single-leg stance, preventing Trendelenburg drop) and gluteus maximus (primary sagittal hip stabilizer).
• Exercise Progression: Isometric gluteal sets and supine bridging $\rightarrow$ side-lying hip abduction with neutral/extended hip $\rightarrow$ closed-chain lateral band walks and step-ups $\rightarrow$ single-leg balance and Romanian deadlifts.
• Aquatic Therapy (Hydrotherapy): Eliminates gravitational axial joint loading via water buoyancy (submersion to xiphoid process unloads ~60% of body weight; submersion to neck unloads ~90%). Ideal for Grade III–IV OA patients suffering severe joint pain during terrestrial loading.

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|               Biomechanics of Cane Prescription: Contralateral vs Ipsilateral     |
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| Cane held in CONTRALATERAL hand:                                                  |
|   - Ground reaction force through cane creates an ABDUCTION torque about the      |
|     affected hip (same direction as gluteus medius torque).                       |
|   - Dramatically reduces the required contraction force of the ipsilateral       |
|     gluteus medius muscle.                                                        |
|   - Result: Reduces Total Hip Joint Contact Force (JCF) by up to 50%!             |
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| Cane held in IPSILATERAL hand (INCORRECT):                                         |
|   - Induces lateral trunk lean; gluteus medius must work HARDER to counter torque;|
|     increases joint reaction force and reinforces pathological gait deviations.   |
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4. Femoroacetabular Impingement (FAI) & Acetabular Labral Tears

Femoroacetabular impingement (FAI) is a motion-related mechanical mismatch between the proximal femur and acetabular rim, leading to premature chondrolabral abutment during terminal hip motions.

FAI Morphotypes: Cam vs. Pincer

Note: Over 70% of clinical FAI presentations demonstrate a mixed Cam-Pincer morphology.

Acetabular Labral Tears

The acetabular labrum is a triangular fibrocartilaginous ring that deepens the acetabular socket by 21%, expands articular surface area by 28%, and forms a fluid seal that pressurizes synovial fluid, decreasing joint friction and cartilege stress.

• Clinical Presentation: Deep anterior groin pain, frequently described as an anterior "C-sign" (patient grips the tissue above the greater trochanter with thumb and index finger extending into the groin). Mechanical catching, clicking, pinching, or subjective giving-way.
• Provocative Clinical Tests:
  1. FADIR Test (Flexion, Adduction, Internal Rotation): Patient supine; examiner passively flexes hip to 90°, adducts, and internally rotates the hip. Compresses the anterosuperior femoral head-neck junction directly against the anterosuperior acetabular labrum. Sensitivity is exceptionally high (>90%–99%); a negative FADIR test effectively rules out anterior FAI and labral pathology.
  2. FABER / Patrick Test (Flexion, Abduction, External Rotation): Patient supine; test leg placed into "figure-4" position with lateral malleolus resting on opposite knee. Examiner stabilizes contralateral ASIS and depresses test knee toward the table. Reproduction of anterior groin pain indicates intra-articular hip pathology (labral tear, chondral defect, OA); reproduction of posterior buttock pain points to sacroiliac joint (SIJ) dysfunction.
  3. Hip Scour (Quadrant) Test: Examiner flexes hip and applies compressive axial force along the femoral shaft while sweeping through an arc from internal rotation/adduction to external rotation/abduction. Reproduction of sharp clicking, grating, or pain confirms intra-articular pathology.

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5. Total Hip Arthroplasty (THA): Surgical Approaches & Movement Precautions

Total Hip Arthroplasty (THA) replaces the damaged femoral head and acetabulum with prosthetic components. Early rehabilitation protocols are dictated strictly by the surgical approach selected.

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|                         THA Surgical Approaches & Precautions                     |
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| 1. Posterior / Posterolateral Approach (Most Common):                             |
|    - Tissues Disrupted: Gluteus maximus split, short external rotators detached,  |
|                         posterior capsule opened. Gluteus medius PRESERVED.       |
|    - Movement Restrictions (6-12 weeks):                                          |
|         * NO Hip Flexion > 90°                                                    |
|         * NO Hip Adduction past midline (do NOT cross legs)                       |
|         * NO Hip Internal Rotation past neutral                                   |
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| 2. Direct Anterior Approach (Smith-Petersen / Hueter Interval):                   |
|    - Tissues Disrupted: Internervous plane (TFL [sup. gluteal n.] and sartorius   |
|                         [femoral n.]). NO muscles or tendons detached.            |
|    - Movement Restrictions:                                                       |
|         * NO Hip Hyperextension                                                   |
|         * NO Extreme External Rotation                                            |
|         * NO Combined Extension and External Rotation                             |
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| 3. Direct Lateral Approach (Hardinge):                                            |
|    - Tissues Disrupted: Anterior third of gluteus medius and vastus lateralis     |
|                         detached and repaired. Low dislocation risk.              |
|    - Movement Restrictions:                                                       |
|         * NO Active or Resisted Hip Abduction for 6 to 8 weeks (protects repair)  |
|         * NO Extreme Hip Adduction or External Rotation                           |
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Post-THA Early Rehabilitation & Gait Training Rules

• Early Ambulation: Commences on Post-Operative Day 0 or 1. Weight-bearing status is typically Weight-Bearing As Tolerated (WBAT) when modern uncemented porous press-fit or cemented femoral stems are utilized.
• Bed Mobility & Transfers: In posterior approach, use an abduction wedge or pillow between knees when supine and side-lying (on non-operative side) to prevent accidental adduction past midline. Patients must avoid leaning trunk forward >90° when sitting down or standing up from chairs (use raised toilet seats and firm elevated chairs).
• Stair Navigation Rule: "Up with the good, down with the bad."
  • Ascending: Unaffected (non-operative) limb steps up first, followed by operative limb, followed by crutches/canes.
  • Descending: Crutches/canes step down first, followed by operative limb, followed by unaffected limb.

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6. Clinical Scenario & DHA Exam Traps

Clinical Scenario: Hip Osteoarthritis vs. Lumbar Referral

Scenario: A 63-year-old retired civil engineer presents to an outpatient physical therapy clinic in Dubai with a 9-month history of insidious right groin and anterior thigh pain that worsens during prolonged walking and when rising from a deep armchair. On physical examination:

• Active right hip flexion is limited to 95° with lateral hip pain; active extension produces anterior discomfort.
• Passive right hip internal rotation is measured at 14° in supine (contralateral left hip IR is 36°).
• Hip Scour test with adduction reproduces deep anterior groin catching and familiar ache.
• Straight leg raise (SLR) is negative bilaterally to 80°; lumbar spine active ROM is full and pain-free.
• Radiographs reveal definite femoral and acetabular osteophytes with marked joint space narrowing superolaterally.

Clinical Decision-Making: The patient meets 4 of the 5 criteria of Sutlive's Clinical Prediction Rule for hip osteoarthritis (squatting aggravation, active flexion lateral pain, Scour with adduction groin pain, active extension pain, passive IR ≤25°), conferring a positive likelihood ratio (+LR) of 24.3 and establishing the diagnosis. Initial physical therapy should focus on long-axis manual distraction mobilization (Grade II–III), manual posterior capsular glides, progressive non-weight bearing gluteal strengthening, and prescribing a walking cane to be used in his left (contralateral) hand.

DHA Exam Traps to Avoid

[!WARNING]

• Trap 1: Cane Hand Placement: DHA questions frequently test which hand holds the cane for unilateral hip osteoarthritis or post-THA. The cane MUST be held in the contralateral hand. Holding the cane on the ipsilateral side fails to reduce the gluteus medius contraction demand and actually increases hip joint reaction forces.
• Trap 2: Confusing THA Approach Restrictions: Never select flexion >90° or internal rotation restrictions for a patient who underwent a direct anterior THA! Anterior approach THA disrupts the anterior capsule, meaning hyperextension and external rotation are the primary dislocation vectors. Flexion >90°, adduction, and internal rotation apply strictly to the posterior approach.
• Trap 3: Misinterpreting Craig's Test: When measuring femoral torsion, remember that an angle of 28° represents excessive anteversion, which presents clinically with in-toeing and excessive internal rotation, NOT out-toeing. Out-toeing is caused by retroversion (<8°).