New classification and score for tibial hemimelia

Abstract

Purpose: Previous classifications of tibial malformations are no longer sufficient and practical for clinics and treatment. They are not precisely defined, include incorrect pathological-anatomical definitions, are related to X-ray diagnosis only, miss complete formal types of malformation, or describe too complex concepts not useful for clinical applications (Jones et al., J Bone Joint Surg B 60:31-39, 1978; Kalamchi and Dawe, J Bone Joint Surg B 67:581-584, 1985; Henkel et al., Arch Orthop Trauma Surg 93:1-19, 1978). More precise preoperative diagnosis, including by sonography and MRI and experienced intraoperative analysis of anatomical structures ensure exact description of the pathological-anatomical situation which can be used because of new potential in therapy. Until now, no score was available for detection of additional limb malformations and, therefore, clinical and scientific comparison of the different tibial reduction deficiencies, especially in respect to the success of therapy, was not sufficiently realisable. A new classification and score is presented reflecting the improved therapy currently available.

Methods: In this classification and score the main pathological findings of the complete leg are included (coxa-femur-patella-tibia-fibula-pes), with specific importance of the tibia. Tibial malformations are divided into seven main groups and five of them into two subgroups. The cartilaginous anlage of the tibia which has not yet received much attention in the literature plays an important role in this classification. Only seven main types of tibial defect have to be recognized and, if necessary, additional defects of the whole leg, including the function of the affected parts, can be summarized in a-five-class-system.

Results: With this classification and this score system which was evaluated on 95 affected limbs, with a sex ratio of 51%:49% (male:female), right:left affection, and unilateral:bilateral affection also, we found the sequence of the distribution of types as follows: 61% of cases with type-VII, 15% with type-III, 6% with type-I, 6% with type-V, 5% with type-II, 3% with type-IV, and 3% with type-VI. In comparison with the Jones et al. (J Bone Joint Surg B 60:31-39, 1978), Kalamchi and Dawe (J Bone Joint Surg B 67:581-584, 1985) and Henkel et al. (Arch Orthop Trauma Surg 93:1-19, 1978) classifications the tibial defects in the presented classification are detected more precisely, the pathological anatomical terms are correctly used, the whole leg and all main functions are included and, thus, reference to therapeutical possibilities is given.

Conclusions: The new classification and the score system allow simple, therapeutically relevant, and comprehensive classification and, additionally, scientific comparison of the different pattern of defects described by diverse authors. For daily clinical use the tibial classification only is preferred.

Fig. 1

Classification of tibial reduction defects in seven types and five subgroups (a = with cartilaginous anlage, b = without cartilaginous anlage) according to the severity of the malformation. Black = bone, blue = cartilage. The figure represents a higher maturation level of the lower leg instead of the situation immediately after birth because of the possibility of giving more detailed illustrations. Type-I = hypoplasia, type-II = diastasis, type-III = distal aplasia, type-IV = proximal aplasia, type-V = bifocal aplasia, type-VI = agenesia with double fibula, type-VII = agenesia with a single fibula

Fig. 2

Case 49. Schematic drawing, X-ray, MRI, and score of Weber type-Va tibial hemimelia. No classification is available in the Jones, Henkel, and Kalamchi and Dawe systems

Fig. 3

Case 30. Schematic drawing, X-ray, MRI, and score of Weber type-VIa tibial hemimelia. No classification is available in the Jones, Henkel, and Kalamchi and Dawe systems

Fig. 4

Case 57. Schematic drawing, X-ray, MRI, and score of Weber type-VIIb tibial hemimelia. MRI ap view with flexed knee shows the patella in coronal view

Diagram 1

Distribution of the different types of tibial hemimelia in our sample, in the Weber classification

Diagram 2

Distribution of the different types of tibial hemimelia in our sample, according to the Jones classification

Diagram 3

Distribution of the different types of tibial hemimelia in our sample, according to the Kalamchi and Dawe classification