Musculoskeletal Pathology in Cerebral Palsy: A Classification System and Reliability Study

Abstract

This article presents a classification of lower limb musculoskeletal pathology (MSP) for ambulant children with cerebral palsy (CP) to identify key features from infancy to adulthood. The classification aims to improve communication, and to guide referral for interventions, which if timed appropriately, may optimise long-term musculoskeletal health and function. Consensus was achieved by discussion between staff in a Motion Analysis Laboratory (MAL). A four-stage classification system was developed: Stage 1: Hypertonia: Abnormal postures are dynamic. Stage 2: Contracture: Fixed shortening of one or more muscle-tendon units. Stage 3: Bone and joint deformity: Torsional deformities and/or joint instability (e.g., hip displacement or pes valgus), usually accompanied by contractures. Stage 4: Decompensation: Severe pathology where restoration of optimal joint and muscle-tendon function is not possible. Reliability of the classification was tested using the presentation of 16 clinical cases to a group of experienced observers, on two occasions, two weeks apart. Reliability was found to be very good to excellent, with mean Fleiss' kappa ranging from 0.72 to 0.84. Four-stages are proposed to classify lower limb MSP in children with CP. The classification was reliable in a group of clinicians who work together. We emphasise the features of decompensated MSP in the lower limb, which may not always benefit from reconstructive surgery and which can be avoided by timely intervention.

Keywords: cerebral palsy; contracture; decompensation; deformity; musculoskeletal pathology; spasticity.

Figure 1

The stages of musculoskeletal pathology (MSP) in children with spastic cerebral palsy, from birth to skeletal maturity. Note the overlapping age ranges, and that features of Stage 2 and 3 usually occur together.

Figure 2

A 10-year old boy with spastic diplegia, GMFCS III with iatrogenic crouch gait after bilateral TALs at age 4. The surgeon recorded in the operation note “minimal fixed contracture but severe toe walking”. Equinus in diplegia at age 4 is usually more spastic than fixed and is more safely managed by injections of BoNT-A and AFOs. The MSP at index surgery was Stage 1 and is now Stage 4. There is no reliable intervention for the overlengthened heel-cord.

Figure 3

Stage 3 MSP in a 10-year old boy with very asymmetric spastic diplegia, before (A,B) and five years after SEMLS. (C,D) All the deformities were corrected with conventional SEMLS procedures. He had a marked improvement in gait and function with no relapse at five-year follow-up. No additional interventions for spasticity or contractures were required.

Figure 4

Decompensated pathology with severe crouch gait in a 15-year old girl with spastic diplegia, GMFCS IV (previously GMFCS III) There was no prior intervention apart from injections of BoNT-A. These are “natural history deformities”. The knee flexion contractures measured 45 degrees bilaterally, and the knees were flexed almost 90 degrees during gait. The feet had severe pes valgus and painful hallux valgus. The MAL team concluded that the MSP was Stage 4 with severe decompensation and advised that surgery was unlikely to be beneficial. Bilateral DFEOs and PTS were performed and were accompanied by neurovascular injuries, loss of ambulatory ability and deterioration in transfer ability.

Figure 5

Radiographic features of Stage 4 MSP in the foot. Severe varus deformity of the foot in a 14-year old boy with Type IV hemiplegia, GMFCS II. There are healing fractures of the 4th and 5th metatarsals, from severe chronic overloading. Management to date has been injections of BoNT-A to the gastrocsoleus and tibialis posterior.

Figure 6

Radiographic features of Stage 4 MSP in the knee, in a 16-year old boy with severe crouch gait. There is marked patella alta and stress fracture of the patella with signs of healing with separation at the fracture site.

Figure 7

Radiographic features of Stage 4 MSP at the hip: MRI scan of a 14-year old boy, Type IV, left hemiplegia, chronic neglected hip displacement, GMFCS III. Note the full thickness loss of articular cartilage on the lateral aspect of the femoral head. The left hip was successfully reconstructed, but this is salvage surgery. The lost cartilage does not regenerate, and the hip is destined for premature arthrosis and arthroplasty.