Adductor Magnus Anatomy

Origin

• Adductor (pubofemoral) part: a small area on the inferior (ischiopubic) ramus of the pubis and the ramus of the ischium, deep to the origins of adductor brevis and gracilis.
• Hamstring (ischiocondylar) part: the inferolateral aspect of the ischial tuberosity, immediately adjacent to and partly blended with the origins of the semimembranosus and the conjoint tendon of biceps femoris and semitendinosus.
• Consequence: the ischial tuberosity origin means the adductor magnus is involved in proximal hamstring pathology — an ischial tuberosity avulsion or apophyseal injury frequently involves it, and it is encountered in any posterior approach to the ischium.

Insertion — a continuous sweep down the medial femur

• Gluteal tuberosity (the rough area on the posterior proximal femur, medial to the vastus lateralis origin).
• The entire length of the medial lip of the linea aspera.
• Medial supracondylar line.
• A rounded tendon onto the adductor tubercle — the distal, ischiocondylar portion.
• The insertion is therefore the longest femoral insertion of any muscle, spanning almost the whole shaft. This is why the muscle is encountered at every level of a medial or posteromedial femoral exposure.

The adductor hiatus

• An opening (osseoaponeurotic hiatus) in the aponeurotic distal insertion of the adductor magnus, between the insertion into the medial supracondylar line and the rounded tendon to the adductor tubercle.
• The femoral artery and vein pass through it from the anterior compartment to the popliteal fossa, becoming the popliteal artery and vein at that point, by definition.
• Located roughly at the junction of the middle and distal thirds of the thigh, on the posteromedial aspect.
• Also transmits the posterior division articular branch of the obturator nerve to the knee, running with the popliteal artery.

Named landmarks and measurements

Two nerves, two parts

1. Adductor (pubofemoral) part — posterior division of the obturator nerve

• Root values: L2, L3, L4.
• Course: the obturator nerve arises from the anterior divisions of the ventral rami of L2-L4, descends on the medial border of the psoas, crosses the pelvic brim behind the common iliac vessels, runs along the lateral pelvic wall above the obturator vessels, and exits through the obturator canal approximately 2-3 cm inferolateral to the pubic tubercle.
• The divisions are separated by the obturator externus in the pelvis and canal, and by the adductor brevis in the thigh: the posterior division lies posterior to the adductor brevis and on the anterior surface of the adductor magnus.
• Posterior division supplies: the adductor part of adductor magnus, the obturator externus, variably the adductor brevis, and gives an articular branch to the knee that descends through the adductor hiatus with the popliteal artery to the posterior capsule.

2. Hamstring (ischiocondylar) part — tibial division of the sciatic nerve

• Root values: commonly given as L4, L5, S1 — the same territory that supplies the true hamstrings.
• Course: the branch arises from the tibial division of the sciatic nerve in the posterior thigh, alongside the branches to semimembranosus, semitendinosus and the long head of biceps femoris, and enters the posterior surface of the ischiocondylar portion.

Practical consequences

• Adduction is weakened but never abolished by an obturator lesion — the ischiocondylar part retains its sciatic supply and the pectineus its femoral branch.
• An obturator nerve block or neurectomy cannot abolish adduction for the same reason. This must be explained before neurectomy, and to the operating urologist relying on a block to abolish the adductor jerk during transurethral bladder resection.
• Sciatic (tibial division) lesion: the ischiocondylar part is denervated along with the true hamstrings, while the adductor part remains innervated — the mirror-image MRI pattern.
• The knee articular branch of the posterior division is the anatomical basis of referred medial knee pain in hip pathology, the reason a child with a slipped upper femoral epiphysis, Perthes disease or a septic hip presents complaining of the knee.

Root-value cross-check

• Hip adduction = L2/L3/L4 (obturator) with an L4/L5/S1 (sciatic) contribution via the ischiocondylar part.
• Hip extension = L5/S1 predominantly (gluteus maximus, hamstrings, ischiocondylar adductor magnus).
• Distal medial thigh sensation is the obturator cutaneous branch, from the anterior division.
• Weak adduction with a medial thigh sensory patch localises to the obturator nerve; add quadriceps weakness and the lesion is proximal — lumbar plexus, L2-L4 roots, or a retroperitoneal haematoma, abscess or tumour.

Supply

• Profunda femoris artery — muscular branches, the dominant supply.
• Perforating branches of the profunda femoris — typically three to four, which pierce the adductor magnus on their way from the anterior to the posterior compartment. They also supply the muscle and give nutrient branches to the femur.
• Obturator artery — posterior branch, supplying the proximal muscle near its pubic and ischial origin.
• Medial circumflex femoral artery — proximal supply, and the vessel of concern in the medial approach to the hip.
• Inferior gluteal artery — supplies the ischiocondylar part near the ischial tuberosity, alongside the hamstring origins.
• Femoral artery and, distally, the descending genicular artery contribute near the hiatus and the adductor tubercle.

The vascular anatomy that dominates the clinical picture

The adductor hiatus and the popliteal artery

• The femoral artery becomes the popliteal artery as it passes through the adductor hiatus, and the vessel is relatively tethered there by the aponeurotic margins of the hiatus.
• Distally the artery is tethered again by the fibrous arch of the soleus.
• These two fixed points mean the popliteal artery has limited capacity to accommodate displacement, which is the anatomical explanation for popliteal artery injury in knee dislocation and in displaced distal femoral and proximal tibial fractures: the artery is stretched or torn between two tethered points.
• Consequence for practice: any knee dislocation or grossly displaced distal femoral fracture mandates a documented vascular assessment, including an ankle-brachial pressure index (ABPI), with further imaging when the index is less than 0.9.

The perforators

• The perforating branches of the profunda femoris pass through the adductor magnus to reach the posterior compartment. Dividing the muscle blindly bleeds from a vessel that then retracts into muscle or into the posterior compartment where the sciatic nerve lies.

The descending genicular artery

• Arises from the femoral artery within the adductor canal, just proximal to the adductor hiatus, and gives muscular, saphenous and articular branches. It is the pedicle of the medial femoral condyle vascularised corticoperiosteal flap.

Anterior to adductor magnus

• Adductor brevis proximally and adductor longus distally.
• Posterior division of the obturator nerve, lying on its anterior surface.
• Profunda femoris artery and vein and their perforating branches, which pierce the muscle.
• Distally, the adductor canal contents lie against its posteromedial surface, where the muscle forms the distal posteromedial wall of the canal.

Posterior to adductor magnus

• Semimembranosus, semitendinosus and biceps femoris (the true hamstrings), and the sciatic nerve in the posterior compartment.
• The muscle therefore forms the anterior wall of the posterior compartment and the floor on which the hamstrings and the sciatic nerve lie.

Medial

• Gracilis — the most medial strap and the only biarticular adductor.
• Great saphenous vein in the subcutaneous plane.

Distal

• Adductor tubercle, and between it and the medial epicondyle the MPFL femoral origin.
• Medial epicondyle and the superficial MCL origin distal and anterior.
• Medial head of gastrocnemius arising just posterior to the adductor tubercle region.
• Popliteal fossa contents beyond the hiatus.

The adductor canal — the distal relationship

• Extent: from the apex of the femoral triangle (where the medial border of sartorius crosses the medial border of adductor longus) to the adductor hiatus.
• Anterolateral wall: vastus medialis.
• Posteromedial wall: adductor longus proximally, adductor magnus distally.
• Roof: the vastoadductor membrane, deep to the sartorius.
• Contents: femoral artery, femoral vein, saphenous nerve, nerve to vastus medialis, and the descending genicular artery arising within it.

Structures at risk in the adductor magnus territory

Vascular injury at the adductor hiatus

Why the anatomy matters

• The femoral artery and vein become the popliteal artery and vein as they pass through the adductor hiatus in the aponeurotic insertion of the adductor magnus.
• The artery is tethered at the hiatus proximally and by the fibrous arch of the soleus distally. Between those two fixed points it cannot accommodate displacement.

Injury patterns

The adductor tubercle as the MPFL landmark

The three medial landmarks, in order

1. Adductor tubercle — the rounded tendinous insertion of the adductor magnus, at the distal end of the medial supracondylar line, proximal and slightly posterior to the medial epicondyle.
2. Medial epicondyle — distal and anterior to the tubercle; the origin of the superficial medial collateral ligament.
3. MPFL femoral origin — between the adductor tubercle and the medial epicondyle, slightly distal and posterior to the tubercle.

Why the adductor magnus tendon is the practical landmark

• The tubercle can be difficult to identify by palpation alone in a thick knee, but the adductor magnus tendon is a firm, easily traced cord leading directly to it. Following the tendon distally reliably finds the tubercle, and from there the MPFL origin.
• Quantitative cadaveric mapping of the medial knee has described the MPFL femoral attachment in relation to the adductor tubercle and the medial epicondyle, and has defined the superficial MCL femoral attachment as a distinct site lying distal and anterior to the adductor tubercle.
• Intraoperatively, fluoroscopic confirmation on a true lateral — using a radiographic point localised in relation to the posterior cortical extension line and the level of the posterior origin of the medial femoral condyle — has been proposed as more reliable than palpation of the bony landmarks alone. Femoral tunnel malposition is a well-recognised technical error in MPFL reconstruction.

Consequences of femoral tunnel malposition

The adductor magnus tendon as a fixation point

• Adductor magnus tendon sling techniques for MPFL reconstruction: the distal adductor magnus tendon, left attached to the adductor tubercle, is used as a pulley or fixation point for a gracilis or semitendinosus graft, or as the graft itself. This avoids drilling a femoral tunnel altogether.
• This is particularly attractive in children, where a femoral tunnel adjacent to the distal femoral physis risks growth disturbance. Physeal-sparing techniques built around the adductor magnus tendon are a recognised option for paediatric patellar instability.
• In posterior cruciate and multiligament surgery, the adductor magnus tendon and the adductor tubercle serve as reference points for medial-side reconstruction tunnels.

Other landmark uses

• Medial femoral condyle vascularised corticoperiosteal flap: based on the descending genicular artery, which arises just proximal to the adductor hiatus. The adductor magnus and its tendon define the field.
• Distal femoral osteotomy: the adductor tubercle and the adductor magnus insertion mark the proximal extent of a medial closing-wedge or opening-wedge distal femoral osteotomy, and the muscle must be elevated to expose the medial cortex.
• Medial approach to the distal femur: the interval between the vastus medialis anteriorly and the adductor magnus posteriorly, with the adductor magnus tendon as the posterior landmark and the vessels at the hiatus as the posterior danger.

Adductor magnus strain

• Mechanism: high-velocity eccentric loading during sprint acceleration, hurdling or a change of direction, with the hip abducted and extending.
• Presentation: deep posteromedial thigh pain, often described by the athlete as neither a hamstring nor a groin injury, with impaired acceleration as the functional hallmark — because the ischiocondylar part is a hip extensor whose moment arm is greatest with the hip flexed.
• Frequently mislabelled as a hamstring strain (because of the posterior location and the ischial origin) or as an adductor strain (because of the medial location). MRI localises it precisely.
• Management: criteria-based rehabilitation as for other muscle injuries, with a deliberate emphasis on hip extension and eccentric adduction loading rather than knee flexion work, because the muscle does not cross the knee.
• Return-to-play criteria: pain-free full range, no tenderness, pain-free maximal resisted adduction and resisted hip extension, restored strength on dynamometry, and completed sport-specific progression through acceleration and change of direction before match play.

Ischial tuberosity avulsion and proximal hamstring injury

• The ischiocondylar origin blends with the hamstring origins at the inferolateral ischial tuberosity, so the adductor magnus is involved in:
  • Ischial apophyseal avulsion in the adolescent athlete — managed almost always non-operatively, with radiographs mandatory to make the diagnosis.
  • Proximal hamstring avulsion in the adult — where the extent of tendon involvement determines whether surgical repair is offered.
• Practical point: in a posterior approach to the ischial tuberosity, the adductor magnus origin is encountered alongside the hamstring origins and must be recognised.

Obturator neuropathy and the posterior division

• A complete obturator nerve lesion denervates adductor longus, brevis, gracilis and the adductor part of magnus, with relative sparing of the ischiocondylar part and the pectineus. Adduction is weakened, not abolished.
• Causes: pelvic and acetabular surgery, pelvic fracture, obstetric compression, gynaecological and urological surgery, tumour or lymphadenopathy, pelvic haematoma, obturator hernia, and in athletes fascial entrapment at the exit from the obturator canal over the short adductor.
• Investigation: MRI of the pelvis to exclude a mass or hernia; electromyography of the adductors, ideally after exercise provocation; a diagnostic obturator nerve block.
• The selective MRI denervation pattern is a reliable localiser and should prompt a search for a pelvic cause.

Adductor compartment syndrome

• Rare but recognised, most often after crush injury, a large adductor haematoma (particularly with anticoagulation), reperfusion, or prolonged compression.
• Presents with a tense tender medial thigh, pain out of proportion, and pain on passive hip abduction (which stretches the adductors).
• Treatment: medial thigh fasciotomy through a longitudinal medial incision, combined with a lateral incision when the anterior compartment also requires decompression.

Adductor magnus in adductor release

• In an adductor release for spastic hip displacement, the sequence is adductor longus, then gracilis, then adductor brevis (partial), then pectineus if abduction remains restricted. The adductor magnus is rarely released, for three anatomical reasons:
  1. The perforating branches of the profunda femoris pass through it, so blind division bleeds.
  2. The sciatic nerve and the true hamstrings lie immediately behind it in the posterior compartment.
  3. Its ischiocondylar part is a hip extensor whose loss would compromise standing and transfers in a child whose extension power is already limited.
• Where a deeper release is genuinely required it is performed under direct vision with deliberate control of perforators, addressing only the anterior adductor portion.
• Target for the whole release: approximately 40-45 degrees of abduction per side.
• Avoid a complete anterior branch obturator neurectomy — abduction contracture risk, and adduction cannot be abolished anyway.
• Selection matters more than technique: outcome after soft-tissue release relates to age at surgery, the preoperative migration percentage and the degree of acetabular deficiency, and a proportion of hips displace further despite release and require later reconstruction.

The medial (Ludloff) approach to the hip

• The original Ludloff interval passed between adductor brevis and adductor magnus — behind the brevis and in front of the magnus, which is where the posterior division of the obturator nerve lies and which brings the surgeon closer to the medial circumflex femoral artery. The Ferguson modification works anterior to the adductor brevis, avoiding both, and is the safer plane.
• Blocks to reduction released: the iliopsoas tendon at the lesser trochanter, the ligamentum teres, the pulvinar and the transverse acetabular ligament. Capsulorrhaphy is not possible, residual dysplasia is common, and avascular necrosis is the feared complication; immobilise in the human position, roughly 100 degrees of flexion and 45-55 degrees of abduction.

Medial and posteromedial approaches to the femur

• The adductor magnus has the longest femoral insertion of any muscle, so it is encountered at every level of a medial or posteromedial femoral exposure, and the adductor tubercle marks the proximal extent of a medial distal femoral osteotomy.
• The critical rule: the perforating branches of the profunda femoris pass through the muscle, and the sciatic nerve lies immediately behind it. Divide it only under direct vision, control perforators deliberately, and never chase a retracted vessel posteriorly.
• Distally, at and beyond the adductor hiatus, the popliteal vessels lie immediately deep to the muscle — the reason retractors here must be seated on bone and placed under vision, and why flexing the knee relaxes the vessels.