Epiphysiodesis for Leg-Length Discrepancy

Surgical Indications

Ideal Candidate

• Predicted leg-length discrepancy at maturity of roughly 2 to 5 cm — the sweet spot for epiphysiodesis
• Sufficient growth remaining in the long limb to make up the discrepancy before physeal closure
• Skeletally immature — bone age before the end of growth (broadly girls up to ~14 years, boys up to ~16 years bone age, but timing is calculated individually)
• A family who understands and accepts the loss of final height in exchange for avoiding lengthening

Relative Indications

• Discrepancy of less than 2 cm rarely needs surgery — shoe raise or observation is usually sufficient
• Discrepancy of 2 to 2.5 cm may be managed non-operatively in some patients; epiphysiodesis offered if symptomatic or progressive
• Mild discrepancy in the context of an underlying syndrome where lengthening morbidity is undesirable

Contraindications

Absolute:

• Skeletal maturity reached (physis closed — no growth left to arrest)
• Predicted discrepancy greater than 5 cm where shortening the long limb would leave the patient unacceptably short — favour lengthening
• Active infection at the operative site

Relative:

• Very large discrepancies better served by lengthening (or combined lengthening plus contralateral epiphysiodesis)
• Significant short stature where any height loss is poorly tolerated
• Uncertain or unreliable growth prediction (insufficient serial data, ambiguous bone age)

Why Timing Is Everything

The entire success of the operation depends on doing it at the moment when the growth that the long limb has left to give exactly equals the discrepancy you wish to correct. Arrest is permanent and immediate — the physis stops growing from the day of surgery.

• Too early — the long limb stops growing while too much growth remains; the short limb overtakes it → overcorrection (now the previously short leg is longer)
• Too late — insufficient growth remains in the long limb to make up the difference → undercorrection (residual discrepancy)

Growth Prediction Drives the Operative Date

Three validated methods are used (covered in detail in the next tab):

• Green-Anderson growth-remaining charts (built on Menschik data)
• Moseley straight-line graph
• Paley multiplier method

All require bone age, not chronological age. A delayed or advanced skeletal age of one to two years substantially changes the remaining-growth estimate.

Bone Age Assessment

Skeletal maturity, not the calendar, determines remaining growth.

• Greulich-Pyle atlas: left hand and wrist radiograph compared to standard plates — the standard method across childhood
• Sauvegrain (elbow) method: uses the ossification of the elbow during the pubertal growth spurt — more discriminating around puberty when timing decisions are most sensitive
• A discrepancy of one to two years between bone age and chronological age is common and clinically important

Normal Physeal Growth Rates

Implication for surgery: To remove length you arrest the physis (or physes) contributing the relevant growth. For a femoral-side discrepancy, arrest the distal femur; for combined correction, arrest distal femur AND proximal tibia on the long side.

Growth-Prediction Methods

Green-Anderson Growth-Remaining Charts

• Based on longitudinal data (Menschik) of normal limb growth
• Plot remaining growth of the distal femur and proximal tibia against skeletal age
• Allows the surgeon to read off how much growth is left at a given bone age and choose when to arrest to remove the desired length
• Strength: directly gives growth-remaining figures; Weakness: assumes the child follows normal percentile growth

Moseley Straight-Line Graph

• Transforms the non-linear growth data into a straight line so that serial measurements of the short and long limbs plot as lines
• Skeletal-age reference lines are drawn; the effect of epiphysiodesis is shown as a change in slope of the long-limb line
• Strength: visually integrates multiple serial measurements and lets you simulate the timing of surgery; requires at least two or three data points for accuracy

Paley Multiplier Method

• Uses a multiplier (derived from databases of normal growth, specific for age and sex) applied to the CURRENT discrepancy or current bone length to predict the value at maturity
• Predicted discrepancy at maturity = current discrepancy x multiplier (for congenital, proportionate discrepancies)
• Strength: a single time-point calculation, no need for serial data; quick and widely used. Weakness: assumes the discrepancy grows proportionately (best for congenital causes)

Relevant Surgical Anatomy

Distal Femoral Physis

• Undulating, with anterior and posterior portions — the most complex physis, which is why open Phemister or percutaneous drilling must address its full three-dimensional extent
• Approached medially and laterally just above the joint line, anterior to the collateral ligament origins
• The peripheral perichondrial ring (ring of LaCroix / zone of Ranvier) must be ablated for complete arrest — residual peripheral physis causes deformity

Proximal Tibial Physis

• Lies just distal to the joint line; the tibial tubercle apophysis (anteriorly) is part of this growth complex
• Common peroneal nerve wraps around the fibular neck laterally — at risk with lateral proximal tibial dissection or instrumentation
• The proximal tibiofibular relationship matters — combined tibial epiphysiodesis often includes the proximal fibular physis to avoid a relatively long fibula

Fluoroscopic Landmarks

• The physis is seen as a lucent transverse line; AP and lateral imaging are both required because the physis is not flat
• Curette and drill must reach the central, anterior and posterior portions, not just the easily accessed peripheral margins

Positioning and Preparation

Patient position: Supine on a radiolucent table with the affected (long) limb prepped free. Image intensifier from the opposite side. A small bump under the ipsilateral hip helps for lateral imaging.

Anaesthesia: General anaesthesia. A tourniquet may be applied to the thigh but is not always required for percutaneous techniques.

Imaging: Image intensifier is mandatory — both AP and lateral views to localise the physis and confirm complete ablation across its undulating surface.

Consent: Counsel specifically on the irreversible nature of arrest, the risk of over- or undercorrection from mistiming, angular deformity from incomplete/asymmetric arrest, the loss of final height, infection, and (for proximal tibia) common peroneal nerve injury.

Percutaneous Drill / Curette Epiphysiodesis (Canale / Bowen)

The most widely used modern technique — minimally invasive, low morbidity, day-case.

Step 1: Localise the Physis Under Fluoroscopy

Using AP and lateral image intensifier, mark the medial and lateral physeal positions on the skin. For the distal femur this is just above the femoral condyles; for the proximal tibia just below the joint line (and the proximal fibula if combined).

Step 2: Make Stab Incisions and Insert a Cannula

Make small medial and lateral stab incisions over the physis. Insert a drill/cannula down to the physis under fluoroscopic control, confirming the position is in the centre of the physis on AP and lateral views.

Step 3: Drill and Curette the Physis

Through each portal, drill across the physis and then use a curette to thoroughly remove the physeal cartilage centrally, anteriorly and posteriorly, creating a cavity that bridges epiphysis to metaphysis. The aim is complete destruction of the growth plate so that bony bridging occurs.

Step 4: Confirm and Close

Confirm symmetric, complete ablation across the whole physis on AP and lateral fluoroscopy. Irrigate, close the stab incisions with absorbable sutures, and apply a simple dressing. No internal fixation is required for the drill/curette technique.

Open Phemister Technique (Classic)

The original described technique — reliable but more invasive than percutaneous methods.

1. Make medial and lateral longitudinal incisions over the physis
2. Expose the physis and cut a rectangular block of bone spanning the physis (epiphysis to metaphysis) with an osteotome
3. Curette the remaining physeal cartilage from the bed
4. Rotate the bone block 90 to 180 degrees and replace it so that bone bridges the physis, promoting bony arrest
5. Close in layers

Phemister gives direct visual confirmation of physeal removal but at the cost of larger incisions and longer recovery than the percutaneous drill/curette method.

Percutaneous Transphyseal Screws (PETS)

Cannulated screws are placed obliquely across the physis (typically two screws, medial and lateral) to bridge and arrest the growth plate.

• Screws are inserted percutaneously under fluoroscopy from the metaphysis, across the physis, into the epiphysis
• Theoretically more controllable and described as relatively reversible if removed early before the bridge consolidates (though true reversibility is debated)
• Useful where hardware-mediated arrest is preferred; hardware can later be removed
• Risks include screw misplacement, asymmetric arrest if the two screws do not span the physis evenly, and hardware-related irritation

Key outcome caveat (evidence): Arrest with PETS is GRADUAL, not immediate, and is frequently incomplete. In the Ilharreborde maturity series the final loss of growth was only about 66% of that predicted pre-operatively — so the planned correction should be OVER-estimated to compensate. Crucially, tibial PETS produced a valgus deformity in 20% of patients and a high revision rate, leading those authors to ABANDON PETS in the proximal tibia while continuing to use it in the femur. This contrasts with the immediate, complete arrest of a well-performed drill/curette epiphysiodesis.

Expected Outcomes

• When timing and growth prediction are accurate, epiphysiodesis reliably equalises discrepancies in the 2 to 5 cm range with low morbidity and an excellent day-case recovery profile
• The percutaneous drill/curette technique gives results comparable to the open Phemister technique with smaller scars and faster recovery — it is the most commonly used method today
• The principal determinant of success is the accuracy of the timing decision, not the technique used

Post-operative Protocol

Early Phase

• Weight-bearing: Most percutaneous epiphysiodesis patients mobilise weight-bearing as comfort allows within days; open Phemister may require a short period of protected weight-bearing
• Dressing and wounds: Simple dressings over stab incisions; absorbable sutures
• Analgesia: Simple analgesia is usually sufficient given the minimally invasive nature
• Return to school / activity: Within one to two weeks for percutaneous technique; longer for open

Surveillance Until Maturity

• Standing long-leg radiographs / scanogram: at intervals (commonly every 3 to 6 months) to confirm that the limb lengths are converging as predicted and that NO angular deformity is developing
• Watch for angular deformity: a developing valgus or varus signals incomplete/asymmetric arrest — detect early so it can be addressed before maturity
• Recalculate: compare actual versus predicted convergence; if undercorrection is emerging, plan a contralateral compensatory procedure or future lengthening

What Examiners Want to Hear

• An explicit statement that the procedure is irreversible and timing-dependent
• Correct use of BONE age and at least one named prediction method
• Recognition that complete, symmetric arrest is essential to avoid deformity
• Honest counselling on the height trade-off versus lengthening
• A surveillance plan with serial long-leg imaging until skeletal maturity