High Yield Overview
GLUTEUS MEDIUS
The Rotator Cuff of the Hip
L4-S1Roots
LateralFacet
AbductionAction
StancePhase
FUNCTIONAL ROLES
Mover
PatternPrimary Hip Abductor
TreatmentResisted Abduction
Stabilizer
PatternPrevents Pelvic Tilt in Stance Phase
TreatmentTrendelenburg Test
Rotator
PatternAnterior=IR, Posterior=ER
TreatmentSecondary Flexion
Critical Must-Knows
- Originates from the Gluteal Surface of the Ilium (between Anterior and Posterior Gluteal Lines).
- Inserts onto the Lateral and Superoposterior Facets of the Greater Trochanter.
- Innervated by the Superior Gluteal Nerve (L4, L5, S1).
- Damage causes a positive Trendelenburg Sign (Pelvis drops to the CONTRALATERAL side).
- Commonly implicated in Greater Trochanteric Pain Syndrome (GTPS).
Examiner's Pearls
- "The 'Safe Zone' for intragluteal injection is the Upper Outer Quadrant (to avoid Sciatic and Superior Gluteal Nerves).
- "Trendelenburg Gait is uncompensated (pelvis drops); Duchenne Gait is compensated (trunk leans to affected side).
- "Tears behave like Rotator Cuff tears: Degenerative, painful, and prone to fatty atrophy.
- "The Superior Gluteal Nerve runs between Gluteus Medius and Minimus.
Clinical Imaging
Imaging Gallery
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Surgical Hazards
Superior Gluteal Nerve
Proximal Extent.
- Running the split in a Hardinge approach too proximally (greater than 5cm from tip of GT) risks denervating the anterior tensor fasciae latae and anterior gluteus medius fibres.
- Result: Persistent limp (Trendelenburg).
Sciatic Nerve
Posterior Relation.
- Although Gluteus Medius covers it, the Sciatic nerve emerges deep to Pyramidalis (Piriformis). Deep injections or incorrect retractor placement in the posterior approach can cause palsy.
- Safe Zone: Upper Outer Quadrant for injections minimizes risk.
| Structure | Origin | Insertion | Nerve |
|---|---|---|---|
| Gluteus Maximus | Post Ilium/Sacrum | ITB / Gluteal Tuberosity | Inferior Gluteal (L5-S2) |
| Gluteus Medius | Ilium (b/w Ant/Post Lines) | GT (Lateral Facet) | Superior Gluteal (L4-S1) |
| Gluteus Minimus | Ilium (b/w Ant/Inf Lines) | GT (Anterior Facet) | Superior Gluteal (L4-S1) |
| Tensor Fasciae Latae | ASIS / Iliac Crest | ITB | Superior Gluteal (L4-S1) |
Mnemonic
SIPGluteal Nerves
S
Superior
Gluteal Nerve (Medius, Minimus, TFL)
I
Inferior
Gluteal Nerve (Maximus)
P
Posterior
Cutaneous Nerve of Thigh
Memory Hook:Major nerves of the gluteal region.
Mnemonic
LAMPInsertions on Greater Trochanter
L
Lateral
Gluteus Medius (Lateral Facet)
A
Anterior
Gluteus Minimus (Anterior Facet)
M
Medial
Obturator Externus/Internus (Trochanteric Fossa)
P
Posterior
Piriformis (Superior/Posterior Facet)
Memory Hook:The facets of the Greater Trochanter.
Mnemonic
Sound Side SinksTrendelenburg Test
Sound
Healthy
Side
Side
Contralateral
Pelvis
Sinks
Drops
Positive Test
Memory Hook:If strict logic fails, remember the Sound Side Sinks.
Overview
The Gluteus Medius is the 'deltoid of the hip'. It is fan-shaped and covers the Gluteus Minimus. It is critical for normal gait, stabilizing the pelvis in the coronal plane during the single-leg stance phase of walking. Weakness leads to a Trendelenburg gait.
Neurovascular
Origin
- Outer surface of Ilium: Between the Anterior Gluteal Line and the Posterior Gluteal Line.
- Fascia: Also originates from the overlying Gluteal Aponeurosis (covering fascia).
Insertion
- The fibers converge into a strong tendon.
- Greater Trochanter: Specifically the Lateral Facet and the Superoposterior Facet.
- Bursa: Two bursae are associated:
- Trochanteric Bursa: Between the tendon and the Greater Trochanter (main cause of GTPS).
- Subgluteus Medius Bursa: Deep to the muscle near insertion.
Surface Anatomy
Palpable Landmarks
- Iliac Crest: The superior border of the muscle.
- Greater Trochanter: The insertion point. Palpable on the lateral aspect of the hip.
- ASIS: Anterior Superior Iliac Spine.
Injection Safety (Upper Outer Quadrant)
- Draw a line from PSIS to Greater Trochanter.
- Injection should be superior and lateral to this line (Upper Outer Quadrant).
- This avoids the Sciatic Nerve (which is medial and inferior) and the Superior Gluteal Neurovascular bundle (which is deep but central).
Identifying these landmarks is crucial for safe practice to avoid iatrogenic nerve injury.
Classification Systems
MRI Classification of Tears
- Grade 1: Peritrochanteric edema (Bursitis/Tendinosis).
- Grade 2: Partial thickness tear.
- Grade 3: Full thickness tear (undisplaced).
- Grade 4: Full thickness tear with retraction (less than 2cm).
- Grade 5: Massive retraction (greater than 2cm) with fatty atrophy.
This classification guides the decision between endoscopic repair, open repair, and muscle transfer.
Clinical Assessment
Trendelenburg Test
Assessment of Stability.
-
Patient stands on ONE leg (the affected leg).
-
Negative (Normal): The contralateral pelvis rises (abductors pull ipsilateral pelvis down to level).
-
Positive (Abnormal): The contralateral pelvis DROPS.
-
Mechanism: Weakness of the stance-leg Gluteus Medius.
-
Note: The test must be held for 30 seconds to detect subtle weakness (fatigue).
Gait Patterns
Compensated vs Uncompensated.
- Trendelenburg Gait: Uncompensated. Pelvis drops with each step on affected side.
- Duchenne Gait: Compensated. Patient leans trunk TOWARDS the affected side during stance to shift center of gravity and reduce abductor demand.
- Bilateral Weakness: Results in a "Waddling Gait" (often seen in hip dysplasia or myopathy).
Resisted Abduction
- Patient in lateral decubitus.
- Abduct leg against gravity and resistance.
- Result: Pain indicates tendinopath, Weakness indicates tear or nerve palsy.
Pathology: GTPS
Greater Trochanteric Pain Syndrome (GTPS)
- Formerly called "Trochanteric Bursitis".
- Now understood as a spectrum: Tendinosis → Partial Tear → Complete Tear.
- "Rotator Cuff of the Hip": Similar pathophysiology to shoulder cuff disease.
- Risk Factors: Female gender (wider pelvis → increased varus moment), Obesity, LLD (Leg Length Discrepancy).
Understanding the mechanical overload is key to successful conservative management.
Investigations
X-Ray
- AP Pelvis: Check for calcification at insertion (calcific tendonitis) or avulsion fractures.
- Fleck Sign: Bony fragment superior to GT suggests avulsion.
Ultrasound
- Excellent for dynamic assessment and guided injection.
- Can visualize fluid in the bursa and tendon tears.
MRI
- Gold Standard.
- Shows muscle quality (fatty atrophy).
- T2 Fluid Signal: At insertion indicates tear/bursitis.
- Evaluate for muscle belly atrophy (nerve injury?).
Fatty infiltration is best assessed on the T1 axial sequence.
Clinical Relevance
Treatment by Pathology
| Condition | Treatment | Rationale |
|---|---|---|
| GTPS (Tendinosis) | Physio, NSAIDs, Injection | Load management usually successful |
| Partial Tear | PRP? Shockwave? Repair? | Conservative first. Repair if failed. |
| Full Thickness Tear | Endoscopic/Open Repair | Relieves pain and restores gait |
| Irreparable Tear | Gluteus Maximus Transfer | Salvage for massive retraction |
- Injections: Corticosteroids provide short term relief but may weaken tendon. PRP is controversial but gaining popularity.
Surgical intervention is reserved for those who fail 6 months of dedicated rehabilitation.
Surgical Technique
Anterolateral (Hardinge)
- Concept: Splits the Gluteus Medius (anterior 1/3) and Vastus Lateralis.
- Exposure: Excellent view of acetabulum.
- Risk: Superior Gluteal Nerve injury if split extends more than 5cm proximal to GT.
- Closure: Must repair the tendon meticulously to prevent limp.
Posterior (Moore)
- Concept: Splits Gluteus Maximus (Safe).
- Retraction: Gluteus Medius is retracted anteriorly.
- Risk: Traction injury to Superior Gluteal Nerve if retractor is too vigorous.
The posterior approach relies on the integrity of the anterior abductor muscle sleeve for stability.
Complications
- Persistent Limp: Failure of repair or nerve injury.
- Nerve Injury: Superior Gluteal (Abductor lurch), Sciatic (Foot drop).
- Recurrence: Re-tear rates are significant (10-20%).
- Heterotopic Ossification: Especially with lateral approaches.
Rehabilitation Protocol
- Phase 1 (0-6 weeks): Protected weight bearing (Crutches). No active abduction. Avoid adduction (crossing legs) which stretches repair.
- Phase 2 (6-12 weeks): Wean crutches. Aqua therapy. Isometric abduction.
- Phase 3 (3+ months): Strengthening. Return to sport/full activity.
Prognosis
- Conservative: 70-80% success for GTPS.
- Repair: Good pain relief (90%). Strength recovery is variable and takes longer (1 year).
- Fatty Atrophy: Presence of Goutallier 3/4 changes significantly lowers success rate.
Evidence Base
Gluteus Medius Repair Outcomes
Walsh et al. • JBJS Am (2011)
Key Findings:
- Repair of chronic massive tears resulted in significant pain relief
- Abductor strength improved but remained lower than contralateral side
- Re-tear rate was 25% on MRI at 1 year
Clinical Implication: Repair reliability is high for pain, moderate for strength.
Endoscopic vs Open Repair
Domb et al. • Arthroscopy (2013)
Key Findings:
- No significant difference in PROMs (Patient Reported Outcome Measures)
- Endoscopic group had lower complication rate
- Endoscopic learning curve is steep
Clinical Implication: Endoscopic repair is a viable alternative for partial/small tears.
Hardinge Approach Morbidity
Ramesh et al. • CORR (2002)
Key Findings:
- Persisting limp seen in 14% of patients after Hardinge approach at 1 year
- EMG changes in Superior Gluteal Nerve found in 30%
- Strict adherence to safe zone (less than 3cm split) is key
Clinical Implication: Respect the 5cm rule (or 3cm for absolute safety)!
Greater Trochanteric Pain Syndrome
Segal NA et al. • Arch Phys Med Rehabil (2007)
Key Findings:
- GTPS prevalence 10-25% of hip pain referrals
- Often involves tendinopathy not just bursitis
- Female predominance
- Response to conservative measures in majority
Clinical Implication: GTPS is primarily tendinopathy - address the tendon, not just the bursa.
Goutallier Classification in Gluteus Medius
Strobel K et al. • Radiology (2004)
Key Findings:
- Fatty infiltration predicts repair outcomes
- Grade 3-4 changes indicate poor prognosis
- MRI assessment essential before repair
- Similar to rotator cuff prognostication
Clinical Implication: Assess muscle quality on MRI before considering repair - severe atrophy predicts failure.
Viva Scenarios
Practice these scenarios to excel in your viva examination
VIVA SCENARIOStandard
Scenario 1: Post-THR Limp
EXAMINER
"A 70F presents 6 months after a Hardinge approach THR (Total Hip Replacement). She has a persistent limp. Why?"
EXCEPTIONAL ANSWER
First, I must differentiate pain (Antalgic) from weakness (Trendelenburg). If painless, it is likely abductor deficiency. Causes include: 1. Failure of tendon repair, 2. Superior Gluteal Nerve injury (split too proximal), or 3. Pre-existing atrophy not addressed. I would examine the gait (uncompensated vs compensated), perform a Trendelenburg test, and check for leg length discrepancy (which can mimic a limp).
KEY POINTS TO SCORE
Antalgic vs Trendelenburg Gait
Nerve vs Tendon vs LLD
Hardinge Approach risks
COMMON TRAPS
✗Assuming it is infection (usually painful)
✗Missing LLD
LIKELY FOLLOW-UPS
"How do you investigate?"
"Ultrasound or MRI (MARS sequence) to view the tendon integrity. EMG to check nerve function."
VIVA SCENARIOStandard
Scenario 2: Lateral Hip Pain
EXAMINER
"50F office worker, localized lateral hip pain, worse at night lying on that side. No trauma. X-ray normal. Diagnosis?"
EXCEPTIONAL ANSWER
This is classic Greater Trochanteric Pain Syndrome (GTPS). It is likely gluteus medius tendinosis or bursitis. I would assess for tenderness over the GT, pain with resisted abduction, and exclude intra-articular pathology (FADIR test). Management starts with load management, NSAIDs, and physiotherapy. Injections (Cortisone/PRP) are second line.
KEY POINTS TO SCORE
GTPS clinical features
Sleep disturbance
Intra- vs Extra-articular differentiation
COMMON TRAPS
✗Calling it 'Bursitis' only (usually tendinopathy)
✗MRI immediately (clinical diagnosis)
LIKELY FOLLOW-UPS
"Conservative management failed for 12 months. MRI shows full thickness tear. What now?"
"Offer surgical repair (Open or Endoscopic)."
VIVA SCENARIOStandard
Scenario 3: The Safe Zone
EXAMINER
"You are performing a lateral approach and need to extend your split proximally. How far can you go?"
EXCEPTIONAL ANSWER
The classic teaching is 5cm proximal to the tip of the Greater Trochanter. However, anatomical studies show the inferior branch of the Superior Gluteal Nerve can be as close as 3cm. I would stay within 3cm to be safe, or use a definitive interval (Watson-Jones) if I need more exposure.
KEY POINTS TO SCORE
5cm rule (Classic)
3cm rule (Anatomical)
Nerve course
COMMON TRAPS
✗Splitting blindly
✗Confusing interval with split
LIKELY FOLLOW-UPS
"What muscle is denervated if you cut the nerve?"
"Tensor Fasciae Latae and the anterior fibres of Gluteus Medius."
MCQ Practice Points
Nerve Injury Effect
Q: Injury to the Superior Gluteal Nerve results in which gait deviation? A: Trendelenburg Gait (Uncompensated) or Duchenne Gait (Compensated). It does NOT causing a foot drop (that is Sciatic/Peroneal).
Fleck Sign
Q: A small bony fleck seen superior to the Greater Trochanter on AP Pelvis X-ray indicates what? A: Avulsion of the Gluteus Medius (or Minimus) insertion. It is the hip equivalent of a Segond fracture (ACL) or bony Bankart (Shoulder).
Insertion Anatomy
Q: Onto which facet does the Gluteus Medius primarily insert? A: Lateral Facet. The Minimus inserts on the Anterior Facet.
Safe Zone
Q: The safe zone for intragluteal injection to avoid the Sciatic Nerve is? A: Upper Outer Quadrant.
Action
Q: Besides abduction, what is the action of the anterior fibers of Gluteus Medius? A: Internal Rotation and Flexion. Posterior fibers do Extension/ER.
Australian Context
- Arthroplasty Approaches: The choice of approach (Direct Anterior vs Posterior vs Lateral) is a hot topic in Australian orthopaedics. The Lateral (Hardinge) is favored for low dislocation rates but criticized for limp. Direct Anterior (DAA) advocates preservation of muscle intervals.
- GTPS Management: High volume of referrals in private practice. Understanding the tiered management (GP → Physio → Surgeon) is essential.
- Fellowship: Hip preservation fellowship often involves endoscopic gluteal repairs.
High-Yield Exam Summary
Anatomy
- •Origin: Ilium (Ant-Post Lines)
- •Insert: Lateral Facet GT
- •Nerve: Sup. Gluteal (L4-S1)
- •Action: Abduct + Stabilize
Clinical
- •Trendelenburg: Contralateral Drop
- •Duchenne: Ipsilateral Lean
- •GTPS: Lat Hip Pain
- •Resisted Abd: Pain/Weakness
Surgery
- •Hardinge: Split less than 5cm
- •Repair: Lat Facet Anchor
- •Safe Zone: Upper Outer Q
- •Nerve @ Risk: Sup Gluteal