Anterior Cruciate Ligament Reconstruction in Patients with Hereditary Abnormalities Involving Connective Tissue

Introduction

Hereditary abnormalities involving connective tissue are among the most common genetic diseases in human beings. Individuals with these disorders demonstrate an array of disease severity and phenotypes, and athletes with these disorders are at increased risk of anterior cruciate ligament (ACL) injury. Surgery to reconstruct the ACL in these patients is associated with a significantly increased risk of complications, and special consideration must be given to all facets of orthopaedic care in an effort to achieve an optimal outcome. In this chapter, we will focus primarily on those heritable disorders of connective tissue that are commonly encountered by surgeons performing ACL reconstruction for which there is some discussion in the existing orthopaedic literature. These disorders include osteogenesis imperfecta (OI), Ehlers-Danlos syndrome (EDS), and Marfan syndrome (MS).

Body

Osteogenesis Imperfecta

OI is a heritable disease of connective tissue that results from mutations in one of the two genes that code for type 1 procollagen, and it is generally characterized by bone fragility. When taking care of patients with this disease, it is important to recognize that any connective tissue related to type 1 collagen may be affected. In addition to bone fragility and multiple fractures, patients with this disorder commonly exhibit pronounced ligamentous laxity, blue sclera, dental abnormalities, spinal and long bone deformity, progressive hearing loss, skin that scars extensively, and cardiovascular manifestations. Diagnosis is usually made on the basis of clinical criteria. The most commonly used classification was developed by Sillence ( Table 125.1 ) and highlights the variability of the disease and its manifestations. Genetic testing is available, although it is often performed only at specialized centers.

TABLE 125.1

Sillence Classification of Osteogenesis Imperfecta

Type	Bone Fragility	Blue Sclera	Abnormal Dentition	Hearing Loss	Inheritance
I	Mild	Present	Absent in IA Present in IB	Present in most	Autosomal dominant
II	Extreme	Present	Present in some	Unknown	Autosomal recessive or sporadic
III	Severe	Bluish at birth	Present in some	High incidence	Autosomal dominant or recessive
IV	Variable	Absent	Absent in IVA Present in IVB	High incidence	Autosomal dominant

Ehlers-Danlos Syndrome

EDS is a group of heritable disorders characterized by hyperelasticity of the skin and hypermobile joints. It has been classified into six major types, and specific mutations have been described for most types ( Table 125.2 ). The preponderance of cases falls into the classical and hypermobile types with vascular being the third most common. Often patients manifest characteristics of varying types and may not fit perfectly into one classification. In addition to hyperelastic skin and hypermobile joints, EDS is also commonly associated with visceral involvement, bleeding, pain syndromes, scoliosis, ophthalmologic abnormalities, and neuromuscular involvement. The clinical course can vary from severe cases to mild or moderate forms.

TABLE 125.2

Classification of Ehlers-Danlos Syndrome

Type	Major Criteria	Minor Criteria	Inheritance	Genetic Defect
Classical	Skin hyperextensibility, widened atrophic scars, joint hypermobility	Smooth skin, molluscoid pseudotumors, subcutaneous spheroids, joint hypermobility, easy bruising, tissue fragility, positive family history	Autosomal dominant	Abnormal type V collagen ( COL5A1 and COL5A2 genes)
Hypermobility	Skin involvement, generalized joint hypermobility	Recurrent joint dislocations, chronic limb pain, positive family history	Autosomal dominant	Reduction in tenascin X (small percentage of cases)
Vascular	Thin skin, arterial intestinal or uterine fragility, extensive bruising, characteristic facial appearance	Acrogeria, small joint hypermobility, tendon or muscle rupture, clubfoot, early onset varicose veins, arteriovenous fistulae, pneumothorax, gingival recession, positive family history	Autosomal dominant	Structural defects of type III collagen ( COL3A1 gene)
Kyphoscoliosis	Generalized joint laxity, severe muscle hypotonia, scoliosis, scleral fragility	Tissue fragility, easy bruising, arterial rupture, Marfanoid habitus, microcornea, osteopenia, positive family history	Autosomal recessive	Deficiency of lysyl hydroxylase (collagen modifying enzyme)
Arthrochalasia	Severe joint hypermobility with subluxations and congenital hip dislocations	Skin hyperextensibility, tissue fragility, easy bruising, muscle hypotonia, kyphoscoliosis, osteopenia	Autosomal dominant	Deficiency of chains in type I collagen (skipped exon 6 in COL1A1 or COL1A2 genes)
Dermatosparaxis	Skin fragility, redundant skin	Soft skin, easy bruising, premature rupture of fetal membranes, umbilical or inguinal hernias	Autosomal recessive	Deficiency of procollagen I ( ADAMST2 gene)

Marfan Syndrome

MS is a heritable disorder of connective tissue that results from a mutation in the fibrillin gene. It is characterized by three dominant features: skeletal changes (long, thin extremities, arachnodactyly, chest deformities, scoliosis, and high pedal arches or pes planus), reduced vision (due to ectopia lentis), and aortic aneurysms. Diagnosis is usually made on the basis of clinical criteria (identification of the above features). Milder forms that predominantly result in only the skeletal manifestations of the disease exist and are difficult to classify. Any patient suspected of having MS should have a slit lamp examination and echocardiogram to rule out ocular and cardiac abnormalities. Genetic testing is available and may be useful in some cases, but is not mandatory to establish the diagnosis.

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