TREATMENT OF SCOLIOSIS USING UNIVERSAL CLAMP AS A HYBRID CONSTRUCT – A PRELIMINARY NOTE

Abstract

The Universal Clamp (U-Clamp) is based in a sub-laminar ribbon and one titanium clamp. The ribbon is passed under the lamina and the clamp is fixed to the rod. The correction is obtained in a very similar way to the old Luque system.

This system allows a gradual force of traction on the lamina (translation) like the Luque’s type system without some of its inconvenience (pullout, the irritation that the tip of wires could cause in the soft tissue, not compatible with the MRI). But also added some advantages, such us a higher capability of traction force, and we can perform the MRI after surgery. And in some severe cases, that in the past we had to do in the same patient, an anterior and a posterior approach, now we can achieve the same amount of correction using only posterior approach with the U-Clamps.

Our department acquired, throughout more than two decades, a wide experience in the surgical correction of the most severe deformities of the spine, using the sub-laminar steel wiring (Luque’s technique). Although we got satisfactory results, the system had some problems that we already mentioned.

The new systems using pedicle screws with or without hooks (considered by most spine surgeons as the “gold standard”) have also some limitations comparing with the Luque system, as Vora, Lenke and al. showed (“Spine” Jan. 2008). It causes frequently hypokyphosis.

We tried a hybrid system to correct the spine deformities in the adolescent and children, some with severe curves.

Since January 2007, 42 patients were operated using proximal hooks and distal screws and the “U-Clamp” in the apex. In our series the mean age was 15 years old, the youngest was 8 and the oldest 19. Most of them were girls (33). The most common aetiology was AIS (24), three were Cerebral Palsy and the rest had different aetiologies. The instrumentation we used was Incompass^® (23) or CD Legacy^® (14). The mean deformity angle before surgery was 78.81° (measured by Cobb method), with the maximum deformity 117° and minimum 53°. After correction the mean angle of deformity was 38.56 (maximum 77 e minimum 18). The preoperative flexibility (PF) (%) was 21.56. The postoperative correction (POC) (%) was 52.42. And the Cincinnati correction index (CCI) (%) was 3.7.

Comparing our patients with the Vora, Lenke and al. (Spine Jan. 2008), our patients had a more severe deformity and where more stiff with the CCI=3.7 (Vora and Lenke, CCI < 1.95)

This new system allows much greater correcting force over the lamina with less wire pullout. Also it doesn’t have the inconvenience of the steel wire if we need to study the patient after surgery with a MRI. The Kyphosis is preserved with this system contrary to the all screw construct.

This system has its place in the spine instrumentation, namely, in situations where the deformity is severe and the osteoporosis is important.