Cerebral Palsy Gait and SEMLS

Cerebral palsy gait is a dynamic, multiplanar orthopaedic problem. The brain lesion is non-progressive, but the musculoskeletal consequences progress because the child grows through abnormal tone, muscle imbalance, weakness, impaired motor control and altered loading. A toddler with dynamic equinus may become a school-aged child with fixed calf contracture, tibial torsion, planovalgus, knee flexion contracture, patella alta and increasing energy cost.

Rarely one tight muscle. The recurring message of the modern literature is that cerebral palsy gait is a whole-limb mechanical problem rather than a list of tight muscles. A visible abnormality may be the primary pathology, a compensation, or the only mechanism keeping the child upright, which is why the assessment follows a sequence rather than becoming a list of operations:

1. Define the functional problem.
2. Classify function and gait pattern.
3. Identify dynamic tone, fixed contracture, weakness, torsion, foot deformity and compensation.
4. Decide whether non-operative care, tone management, orthoses, surgery or surveillance best matches the goal.
5. If surgery is required, plan the whole limb and the rehabilitation pathway.

Who is in front of you. Cerebral palsy is the most common cause of lifelong physical disability beginning in childhood, and orthopaedic gait surgery mainly concerns the ambulant child.

Single-event multilevel surgery is the planned correction of clinically important musculoskeletal deformities at multiple anatomical levels during one operative episode. In ambulant CP, it is usually planned from clinical examination, radiographs, rotational assessment and instrumented gait analysis.

SEMLS is a gait-analysis-informed single-stage strategy for ambulant children with cerebral palsy, designed to correct fixed soft-tissue contractures and bony lever-arm dysfunctions at the hip, knee, tibia, ankle and foot, with one coordinated rehabilitation pathway.

Why it exists. Treating equinus one year, hamstrings another year and femoral anteversion later can create sequential imbalance and repeated rehabilitation cycles. SEMLS corrects the clinically important fixed deformities and lever-arm dysfunctions together, once the gait pattern is sufficiently understood and the child can participate in rehabilitation.

What "single-event" does not mean. It does not mean every abnormality must be treated. The clinically relevant fixed deformities that drive the gait problem are corrected together where this is safer and more logical than serial isolated surgery.

The normal cycle. Gait divides into stance and swing. Stance occupies roughly 60 percent of the cycle - initial contact, loading response, midstance, terminal stance and pre-swing - and swing the remaining 40 percent, as initial swing, mid-swing and terminal swing.

Efficient gait depends on a set of mechanical requirements, and cerebral palsy can disturb any of them:

• Heel strike or controlled initial contact
• Controlled tibial progression over a stable foot
• Adequate stance-phase knee extension without recurvatum or collapse
• Hip extension in terminal stance
• Heel rise and plantarflexion power in terminal stance and pre-swing
• Adequate knee flexion in swing for foot clearance
• Controlled terminal swing knee extension
• Balanced pelvic motion with limited compensatory trunk movement

Why the pattern breaks down. The child with CP loses gait efficiency when tone, weakness, contracture and skeletal alignment disturb that sequence, and a deformity at one level changes the apparent problem elsewhere. The table reads in both directions: from a driver to what it does, and from a visible abnormality back to what may be producing it.

The brain lesion is static; the gait is not. It deteriorates because the child grows through abnormal tone, weakness and lever-arm dysfunction, and that trajectory is what determines when to intervene.

The young child. Spasticity is still largely dynamic - dynamic equinus is the usual example - and the gait pattern is still evolving. Non-operative tone management with botulinum toxin, serial casting and orthoses carries this period: gait analysis is less reliable and soft-tissue lengthenings recur with growth, so early irreversible surgery is avoided.

School age, about 7 to 10 years. The gait pattern matures and becomes reproducible, and fixed contracture and lever-arm dysfunction declare themselves. This is the usual window for gait-analysis-informed SEMLS, once the deformity is fixed and functionally important.

The pubertal growth spurt. Rising body mass and longer levers outstrip plantarflexor and quadriceps strength, and a toe-walking or jump-gait child can collapse into high-energy crouch - the crouch crisis. It is the high-risk window: act before crouch and bony deformity become fixed and irreversible.

Adolescence and adulthood. Crouch is expensive to walk in, and a proportion of GMFCS II-III walkers lose efficient or independent ambulation. Preserving ambulation and energy efficiency is a central goal of well-timed surgery.

CP gait abnormalities arise from neurological and musculoskeletal factors acting together.

The neurological contribution. The lesion produces abnormal tone, weakness, poor selective control and impaired balance, and each of these has a different treatment logic.

• Spasticity - velocity-dependent resistance to stretch.
• Dystonia - involuntary fluctuating postures or movements.
• Co-contraction - simultaneous activation of antagonists, reducing smooth motion.
• Poor selective motor control - inability to isolate hip, knee, ankle and foot movement.
• Weakness - particularly hip extensors, hip abductors, quadriceps, dorsiflexors and plantarflexors.
• Impaired balance - abnormal trunk and pelvic strategies.
• Motor learning differences - persistence of inefficient movement patterns after deformity correction.

The musculoskeletal contribution. These accumulate as the child grows through the abnormal pattern.

• Muscle-tendon contracture.
• Joint contracture.
• Femoral anteversion.
• Tibial torsion.
• Patella alta and extensor mechanism insufficiency.
• Planovalgus or equinovarus foot deformity.
• Hip displacement and pelvic obliquity.
• Scoliosis or spinal imbalance.

Lever-arm dysfunction. Muscles need stable skeletal levers, and even strong muscles cannot work efficiently if the lever is malaligned. Femoral anteversion changes hip rotation and reduces efficient abductor mechanics, while external tibial torsion rotates the foot lever outwards and weakens the plantarflexion-knee-extension couple. Planovalgus shortens and destabilises the foot lever, a midfoot break allows collapse rather than push-off, and patella alta reduces the effectiveness of the quadriceps mechanism and contributes to extensor lag. This is why bony correction and foot reconstruction may be more important than additional soft-tissue lengthening in selected children.

The Rodda and Graham sagittal classification is useful because it links observed gait to treatment reasoning. It should not replace full assessment. Classify each limb separately. Asymmetry between the two sides is common in diplegia - a child may be in jump gait on one side and crouch on the other - and the operative plan then differs limb by limb. Assigning a single pattern to the whole child is a recognised way to end up doing the wrong operation on one leg.

Stiff-knee gait. The problem is reduced or delayed swing-phase knee flexion, with toe drag and poor clearance. Rectus femoris transfer is considered only when the gait-lab and clinical pattern support inappropriate rectus activity, because poor push-off, weakness and poor selective control can also reduce swing knee flexion. Circumduction, hip hiking and vaulting may be compensations for poor clearance rather than problems in their own right.

Rotational gait. Internal rotation gait may come from femoral anteversion, internal tibial torsion, foot deformity or compensation. Derotation decisions should match the functional gait findings rather than a single static measurement.

Scissoring. Assess adductor tone, hip abduction range, hip displacement risk, balance and selective control. Do not treat scissoring in isolation without understanding the hip and the functional goal.

Hemiplegic gait is commonly described using the Winters, Gage and Hicks pattern. The value is not memorising labels; it is linking the involved levels to treatment.

Describe the child, not the operation. Begin with the distribution of involvement and the movement disorder.

• Spastic hemiplegia - one side predominantly involved, often with equinus or equinovarus, drop foot in swing, stiff knee gait or internal rotation gait.
• Spastic diplegia - both lower limbs involved, usually with relative upper limb sparing, commonly showing equinus, jump gait, apparent equinus, crouch, scissoring, internal rotation and planovalgus.
• Quadriplegia - all four limbs involved; gait surgery is less often the primary goal and orthopaedic care commonly focuses on hips, sitting, spine, hygiene, comfort and transfers.
• Dyskinetic or dystonic CP - variable posture and tone may make SEMLS outcomes less predictable if dystonia is dominant.

GMFCS comes from function. The level is assigned or confirmed from observed and reported function, based on what the child does in daily life, with emphasis on sitting, transfers and mobility. Build it from functional questions: does the child walk indoors, outdoors and at school; are stairs possible, and is a rail required; does the child use AFOs, crutches, a walker or a wheelchair; how far can the child walk before fatigue; does the child fall; can the child keep up with peers; are transfers independent; has function declined with growth; and is pain limiting walking?

• GMFCS I - walks without major limitations, but speed, balance, running and jumping may be impaired.
• GMFCS II - walks without handheld mobility devices but has limitations with distance, uneven ground, crowds, inclines or speed.
• GMFCS III - walks with a handheld mobility device and often uses wheeled mobility for longer distances.
• GMFCS IV - self-mobility is limited; powered mobility or substantial assistance is often required.
• GMFCS V - transported in a manual wheelchair, with severe limitations in head and trunk control.

Who the gait operation is for. The common gait-improvement SEMLS group is ambulant CP, especially GMFCS I to III, and particularly spastic diplegia and hemiplegia. GMFCS IV and V children may still need orthopaedic surgery, but the priorities usually shift to hip surveillance, sitting, hygiene, pain, skin protection, hip containment, standing transfers and care rather than efficient community walking.

History. The history should explain why the child is presenting now: tripping, fatigue, pain, loss of walking, brace intolerance, cosmetic concern, hygiene, transfers or school participation. Ask what the child actually does - indoor walking, outdoor walking, stairs, playground, sport, self-care, endurance and community mobility - and what they use to do it, including AFO type, walker, crutches, wheelchair, night splints, how well each is tolerated and whether it leaves pressure areas. Falls deserve detail (frequency, direction, triggers and injuries), as do fatigue (distance before stopping, end-of-day deterioration and recovery time) and pain (hip, knee, foot, back, brace pressure or after activity).

The background that changes the plan. Take the developmental history: prematurity, neonatal course, milestones and any cognitive or communication needs. Ask about seizures, dystonia, medication, selective control concerns and tone management, and about every previous treatment - physiotherapy, strengthening, botulinum toxin, serial casting, orthoses, baclofen, intrathecal baclofen, selective dorsal rhizotomy and prior orthopaedic surgery. Ask too about recent growth spurt, worsening contracture or new functional decline.

Goals and rehabilitation reality. Ask what change would make treatment worthwhile, then ask whether it can be delivered: school support, therapy access, transport, home setup and family capacity.

Observation. Observe before touching the limb. Watch transfers, standing balance, shoes, braces and spontaneous walking, then observe barefoot and braced gait from the side, front and behind, recording:

• Walking speed and endurance
• Initial contact: heel, flat foot or toe
• Knee position in stance
• Hip flexion and pelvic tilt
• Foot progression angle
• Step length and symmetry
• Base width and scissoring
• Trunk lean, arm posture and balance
• Compensations: vaulting, circumduction, hip hiking and excessive pelvic rotation

Physical examination. The examination should explain the gait, not merely document range.

The tests that decide the plan. Each answers a specific question rather than filling a proforma:

• Thomas test - hip flexion contracture
• Hip abduction in flexion and extension - adductor tightness, and relevant to hip surveillance
• Popliteal angle - hamstring length
• Duncan-Ely or prone rectus test - rectus femoris tightness, and a clue to overactivity
• Silfverskiold test - gastrocnemius versus soleus contribution to equinus
• Patellar height and extensor lag - extensor mechanism insufficiency
• Rotational profile - femoral anteversion and tibial torsion
• Foot assessment - hindfoot, midfoot, forefoot, subtalar flexibility and braceability
• Strength and selective motor control - essential before any lengthening decision

Plain radiographs. Request them to answer a question the examination has already raised. Gait planning sits inside the wider CP orthopaedic assessment of hips, spine, contractures, torsion, foot shape and functional goals.

• AP pelvis - migration percentage, acetabular index, femoral head shape, neck-shaft angle, hip subluxation, pelvic obliquity and pain source.
• Standing long-leg radiographs - coronal alignment and mechanical axis when deformity is suspected.
• Foot radiographs - weight-bearing AP and lateral views for planovalgus, cavovarus, midfoot break, talonavicular coverage and calcaneal pitch.
• Spine radiographs - scoliosis or pelvic obliquity when clinically relevant.
• Patellar height imaging - useful when crouch, extensor lag or anterior knee pain is present.

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CT and MRI. CT may help quantify femoral anteversion or tibial torsion when clinical and gait findings are unclear; it should support the decision rather than replace functional assessment. MRI brain is not routinely required for established CP gait planning, but may be appropriate if the neurological diagnosis is unclear, progressive or atypical.

Instrumented gait analysis. It is most useful in complex ambulant CP, especially before SEMLS, and combines video, kinematics, kinetics, dynamic EMG, plantar pressure and temporospatial measures.

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What the gait lab does not replace. It cannot decide whether the family can manage rehabilitation, whether pain is the main complaint, whether school planning is realistic, or whether surgery matches the child's priorities. The report has to be reconciled with the examination, the radiographs and a shared decision.

SEMLS outcomes are reported as the Gait Profile Score, so it is worth knowing what these summary indices are. They turn a gait-laboratory dataset into a single comparable number, and they are how gait quality and treatment response are reported and compared.

A non-progressive brain lesion is the defining feature of cerebral palsy. Before committing a child to a gait-correction pathway, exclude conditions that mimic spastic diplegia but progress, are inherited, or are treatable in a completely different way. A worsening, regressing or strongly familial picture, or an unusually pure dystonia, should prompt neurology review rather than orthopaedic surgery.

Management is matched to function, age, gait pattern, impairments, goals and rehabilitation capacity.

The exact package is individualised, and the procedures below are common options rather than a mandatory list. A modern package may combine soft-tissue balancing, tendon transfers, osteotomies, patellar tendon procedures and foot reconstruction, all linked to one rehabilitation plan.

Hip-level procedures

Adductor lengthening. Indications include adductor contracture, scissoring, reduced abduction, selected hip-at-risk patterns and hygiene or care needs in non-ambulant children. Commonly addressed muscles are adductor longus, gracilis and adductor brevis. Avoid destabilising the hip by treating adductors without considering hip containment.

Iliopsoas lengthening. Indications include hip flexion contracture, excessive anterior pelvic tilt, jump gait and persistent hip flexion in stance. Overlengthening can weaken hip flexion and impair swing advancement.

Femoral derotation osteotomy. Indications include excessive femoral anteversion with internal rotation gait, patellar maltracking or lever-arm dysfunction. Plan the correction from the clinical rotational profile and the gait, and avoid overcorrection into external rotation.

Knee-level procedures

Medial hamstring lengthening. Indications include true hamstring contracture, an increased popliteal angle, knee flexion contracture and excessive knee flexion in stance where hamstrings are a major driver. It is not the default treatment for all crouch gait.

Rectus femoris transfer. Indicated for selected stiff-knee gait with reduced or delayed swing-phase knee flexion and inappropriate rectus femoris activity, so dynamic EMG and kinematics matter. Poor selective control, weak push-off or lever-arm dysfunction may also cause poor knee flexion and should not be mistaken for isolated rectus overactivity.

Distal femoral extension osteotomy. Considered for severe crouch with fixed knee flexion deformity, especially in older children and adolescents. It corrects sagittal knee alignment and is often combined with patellar tendon advancement or shortening when extensor mechanism insufficiency is present.

Patellar tendon advancement or shortening. Indicated when patella alta and extensor lag contribute to crouch. If knee flexion deformity is corrected but patella alta is ignored, crouch may persist.

Tibial-level procedures

Tibial derotation osteotomy. Indications include clinically significant internal or external tibial torsion with abnormal foot progression and lever-arm dysfunction. External tibial torsion is especially important in crouch because it weakens the effective foot-ankle lever.

Calf and ankle procedures

Gastrocnemius recession. Considered when equinus is gastrocnemius-driven with a positive Silfverskiold pattern. In diplegia, gastrocnemius recession may preserve soleus better than tendo-Achilles lengthening.

Tendo-Achilles lengthening. Considered for fixed gastrocsoleus equinus in selected children, more commonly in hemiplegic fixed equinus than in diplegic crouch-prone patterns. Risks include overlengthening, calcaneus, weak push-off and worsening crouch.

Foot procedures

Planovalgus correction. Indications include pain, brace intolerance, midfoot break, progressive deformity and lever-arm failure. Options include calcaneal lengthening osteotomy, medial column procedures, subtalar fusion or triple fusion in older severe rigid deformity.

Equinovarus correction. Indications include lateral border weight-bearing, recurrent sprains, brace difficulty and pressure callosity. Options include split tibialis anterior transfer, split tibialis posterior transfer, tendon lengthening, osteotomy or fusion in severe rigid deformity.

General complications. These are the risks of several osteotomies and soft-tissue procedures performed in one operative episode.

• Pain and delayed recovery.
• Blood loss.
• Wound problems or infection.
• Cast pressure sores.
• Neurovascular injury.
• Delayed union or nonunion after osteotomy.
• Hardware irritation.
• Rehabilitation failure.
• Loss of confidence or temporary loss of walking independence.
• Residual deformity, recurrence or need for revision surgery.

Procedure-specific risks. Each procedure has its own failure mode and its own avoidance principle.

Rehabilitation is part of the indication. A child who cannot complete the rehabilitation pathway may not benefit from the operation.

Before the operation. Define the functional goals and explain the timeline to the family and the school. Optimise strength, nutrition, skin and equipment, plan the wheelchair, walking aids, orthoses and home transfers, and prepare the child for pain, casts, braces and a period of reduced independence.

The early postoperative phase. The priorities are pain and spasm control, neurovascular and wound monitoring, cast and pressure-area care, and safe transfers and positioning. Osteotomies and tendon procedures are protected, and the family is trained.

Recovery. Restore safe range without overstretching repairs, begin muscle activation, and progress weight bearing according to the procedures performed and the fixation used. Optimise the orthoses and strengthen hip extensors, abductors, quadriceps and plantarflexors.

Gait retraining. The child relearns walking with corrected alignment, progresses aids and endurance, and returns to stairs and school participation. Watch for recurrence, weakness, pain and poor brace fit. Maximum functional benefit may take 12 to 24 months.

Cerebral palsy is the most common cause of physical disability beginning in childhood worldwide, but its prevalence, surveillance infrastructure and treatment access differ sharply between high-income and low- and middle-income settings. Gait-correction surgery sits within a wider, internationally consistent care model built on multidisciplinary assessment, structured hip surveillance and instrumented gait analysis where available.

Global epidemiology

Spastic subtypes predominate, and gait-correction surgery mainly concerns ambulant children at GMFCS levels I to III, especially spastic diplegia and hemiplegia. The higher burden in low- and middle-income countries is accompanied by less access to gait laboratories, orthotics and structured rehabilitation, which shifts real-world practice toward clinical decision-making without instrumented analysis.

Major guidance, side by side

Across guidelines the recommendations converge: multidisciplinary assessment, separation of dynamic tone from fixed deformity, gait analysis before complex multilevel surgery, and tone-management options (botulinum toxin, baclofen, selective dorsal rhizotomy) considered alongside orthopaedic correction. Differences are largely in service organisation rather than principle.

Evidence on tone management as part of the pathway

Practice variation

• Gait analysis access: routine in many high-income tertiary centres before SEMLS, but scarce in low-resource settings, where clinical pattern recognition and observational gait analysis carry more weight.
• Tone management: availability of intrathecal baclofen and selective dorsal rhizotomy varies by centre and country, altering the balance between neurosurgical and orthopaedic management.
• Hip surveillance: standardised population programmes are established in some regions (for example Australia, Scandinavia and parts of the UK) but absent elsewhere, changing how late displacement presents.
• Rehabilitation: outcomes after SEMLS depend heavily on access to prolonged structured rehabilitation, which is unevenly available worldwide.

What SEMLS is actually for The strongest evidence supports improved gait quality - kinematics, gait indices, deformity correction - in selected ambulant children. What it does not reliably do is move a child up a GMFCS level. Why it stays unsettled: the trials are small, blinding is impossible, and gait-index improvement is a measurable surrogate while "walks better in real life" is not. Promise a family a straighter, more efficient gait and a long rehabilitation; do not promise a change in functional category.

Whether instrumented gait analysis changes outcome or only changes plans Gait analysis demonstrably alters surgical decisions, but showing that it improves outcomes is far harder, and the transverse-plane rotational data are the least reproducible part of the study. Why it stays unsettled: the honest comparison would randomise children to planning with and without it, which few centres will do, so the case rests on decision-change rather than outcome-change.

Timing, and the trade the timing represents Operating early risks recurrence as the child grows and the deformity reforms; operating late means years of deteriorating lever arms and a harder correction. Why it stays unsettled: there is no validated marker for "the deformity is now fixed enough to correct", so timing rests on serial observation, skeletal maturity and family readiness rather than a threshold.

SEMLS versus tone management, and in what order Selective dorsal rhizotomy and intrathecal baclofen reduce tone; SEMLS corrects the fixed deformity tone has already produced. Why it stays unsettled: the two are complementary rather than competing, but no trial defines the optimal sequence, and a child who has had effective tone reduction early may need a different orthopaedic operation later than one who has not.

Rehabilitation is part of the operation, and it is the part most often unavailable Outcomes depend on a rehabilitation pathway measured in months. Why this matters more than a controversy usually does: where that pathway does not exist, the honest answer may be not to operate - the same operation produces a different result in a different system.

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