Effects of lnterference Fit Screw Length Tibial runnel Fixation For Anterior ruciate Ligament Reconstruction

ABSTRACT

Graft-tunnel mismatch during Arthroscopically assisted anterigr cruciate ligament reconstruction using the cen-tral-third patellar tendon results in less than 20 mm of bone plug remaining in the tibialtunnel. We decided to evaluate the strength of bone plug fixation using inter-ference fit screws that were less than 20mm in iength. Biomechanical testing was performed on 48 porcine hindquarters using 9-mm diameter interference fit screws that measured 12.5, 15, and 20 mm in length. No significant difference was noted between the different-length screws for insertion torque, divergence, stitf-ness, displacement, or load to failure. We believe, therefore, that comparable graft fixation can be achieved in the tibial tunnel using 9-mm diameter interference fit screws that are less than 20 mm long, and that these shorter screws may be useful incases of graft-tunnel mismatch.

Endoscopic single-incision ACL reconstruction using bone-patellar tendon-bone autograft has become increasingly popular because of proposed advantages ofdecreased surgical morbidity by a oiding asecond incision and easier postoperatiye posed  rehabilitation. Despite these proadvantages, several problems  related to graftfixation have been described, including inaccurate graft placement, divergent screw fixation, autograft tendon injury, and suboptimal interference screw fixation of the bone bloek in the tibial tuqnel After the bone plug into the femoral tunael, mismatch between the length of the graft and the tibial tunnel may leave the bone plug protruding from the tunnel,. Shortening the effective length of the plug and potentially  is secured compromising strength of the initial fixation. Although Kenna et al and Lemos et al have recommended that this problem  prevented  by understanding the dimensions of the knee and graft preoperatively and planning the can be an appropriate- length tibial tunnel, Shiffer et al  reported a graft-tunnel mismatch incidence of 26% in their series of 34 endo-scopic ACL reconstructions. The incidence in other series is unpublished.

Options or c6rrecting this mismatch are limited. Further recession of the femoral bone plug risks inaccurate femoral interferenee screw placement and possible graft abrasion by the femoral tunnel. Shortening the bone plug and using a standard interference screw risks tendon laceration by the longer screw. Other options for fixation, including staples or tying sutures in the tibial bone plug around a post, compromise the initial strength of the construct in ssmparison with the relatively rigid fixation of an interference screw. Use of a shorter interference fit screw has not been described in the clinical literature as a solution to this problem.

Several investigations have been performed to evalu-ate the relationship between interference screw diame- ter or length and fixation strength. Brown et al reported no significant effect of screw length on fixation strength for 20- and 25-mm screws in human cadavers. To the best of our  knowledge,  reports of biomechanical testing of shorter interference fit screws, which may  applicable in situations of graft-tunnel not been published. The purpose  mismatch, have ofthis study was  evaluate the failure of 12.5-, 15-, and 20-mm interfer-ence fit screws.

MATERIALS AND METHODS

Hindquarters were obtained from 48 fresh-frozen pigs weighing between 240 and 260 pounds. Bonepatellar ten-grafts-bone grafts were harvested from each pig by removing 10 mm diameter tibial bone plugs, leaving the patellar tendon attached to an intact patella. Each tibial bone plug was noted to have an approximately 15-mm apophysis proximal to a predominately cortical anterior tibial crest.The Tibial bone plugwas cut to 13, 15,or 20 mm lengths to correspond to the length of the cannulated interference screw. The tibial plug was trimmed into a cylindrical shape to snugly fitthrough a 10-mm sizer with less than 2mm of space between the plug and the tunnel wall. The tibial plug was left securely attached to the patellar tendon A No. 2 Ethibond suture (Ethicon, Somenrille, New Jersey) was passed through the patellar tendon as a modKessler suture and was used to pull the graft into the l. This was done to avoid the necessity of creating drill holes in the bone plug and thus weakening it, as noted by Resnick.

Anteroposterior and lateral radiographs were taken of each specimen to evaluate angles of divergence and the number of threads engaged. In those specimens in which  the threads of the ssrew did not fully contact the bone plug, the screw was further advanced and the torque of insertion was  ing  again recorded. Repeat radiographs confirmed firll seat- of the screw. The angle of divergence in both AP and lateral planes was measured usrng the angle forned bylines tilong  the axis of the tunnel and the screw. The number of threads engaged into the plugwas also recorded. The patella was mounted in a steel clamp through which a 3-cm, partially enclosed hole had been made to permit  passage of the patellar tendon. A small, threaded Steinmann pin was passed hrough the proximal aspect of the cannulated screw and locked onto the screw with a emall nut. The distal load was applied, therefore, at the proximal end of the screw.

DISSCUSION

Anterior cnrciate ligament reconstruetion has given many athletes the opportunity to return to their prwious levels of activity with minimal functional d€ficits. Great advances have been made in understanding the biolory of  placement and the technical pitfalls involved in successfirl ligament reconstruction. It is generally agreed that the initial weak link'sf the reconstnrcted knee is at the graft fixatioa site. Consequentfy, much  has been done to investigate tlre factors involved in initial fixation strength: type of graft, nethod of fixation, interfenence screw width/core diameter, screw divergence, and torque of insertion Methods of fixation of insertion.Method of fixation the patellar tendon graft have varied. Kurosnka et al. demonstrated the superiority  9.0-mm interference screws compared with 6.5-dnscrews, butbons, and staples. Pull-out strengths of greater than  400 N have been found in cadaveric studies Using 9-rnm Kurosoka bcrews by Black et al. and Matthews  al.,lo and by Bmwn et aI. when correct€d to the bone density of a young adult. This shength is very close to the 450 N that Noyes and Grmd stated the normal ACL was exposed t0 during activities of daily living. Compromise of fixation may occur by 1) changing screw specifications or 2) straying recognized principles in technical insertion.

In conclusion,  in this study there was a positive  lation between torque of interference  screws insertion and pull-out  strength. There was no significant difference in torque of insertion,  divergence, stiffrress, displacement, or failure load between 12.5, 15,or 20 mm long cannulated 9mm interference  into porcine bone. We believe,therefore, that shorter interference  corre and fit screws may be used clinically in the tibial tunnel without compromise  ing graft fixation.

DAFTAR  PUSTAKA

Aerssens J, Boonen S, Lowet G, et all : Interspesies differences in bone composition, density, and quality : Potential for in vivo bone research.Endocrinology 139:663-670, 1998.

Kenna B, Simon TM, Jackson DW, et all ;Endoscopic ACL reconstruction : A technical note on tunnel length for interference fixation. Arthroscopy 9 : 228-230, 1993

Noyes FR, Butler DR, Grood ES, et all : The strength of the anterior cruciate ligament in humans and rhesus monkeys : Age related and spesies related changes. J Bone Joint Surg 58A:1074-1082,1976.

My Analysis :

Jurnal diatas merupakan salah satu contoh jurnal internasional, dimana jurnal tersebut berisi tentang pengaruh interference fit screw panjang tibialis anak sungai kecil fiksasi untuk anterior ruciate ligamen rekonstruksi. Anterior cnrciate ligamen reconstruetion telah memberikan banyak atlet kesempatan untuk kembali ke tingkat prwious aktivitas mereka dengan minimal fungsional deficits. kemajuan besar telah dibuat dalam memahami biolory penempatan dan perangkap teknis yang terlibat dalam rekonstruksi ligamen successfirl. Hal ini umumnya sepakat bahwa lemah link'sf awal lutut reconstnrcted adalah di situs graft fixatioa. Consequentfy, banyak yang telah dilakukan untuk menyelidiki tlre faktor yang terlibat dalam kekuatan fiksasi awal: jenis korupsi, nethod fiksasi, interfenence lebar sekrup / diameter inti, sekrup divergensi, dan torsi Metode penyisipan fiksasi insertion.Method fiksasi tendon patella graft bervariasi. Kurosnka et al. menunjukkan keunggulan sekrup gangguan 9.0-mm dibandingkan dengan 6,5-dnscrews, butbons, dan staples. Tarik-keluar kekuatan yang lebih besar dari 400 N telah ditemukan dalam studi kadaver Menggunakan 9-RNM Kurosoka bcrews oleh Black et al. dan Matthews al., lo dan dengan Bmwn et al. ketika benar € d kepadatan tulang orang dewasa muda. shength ini sangat dekat dengan 450 N yang Noyes dan Grmd menyatakan ACL normal terkena t0 selama kegiatan hidup sehari-hari. Kompromi fiksasi dapat terjadi oleh 1) mengubah spesifikasi sekrup atau 2) menyimpang prinsip yang diakui dalam penyisipan teknis. Dalam penelitian ini ada lation positif antara torsi gangguan sekrup penyisipan dan tarik-keluar kekuatan. Tidak ada perbedaan yang signifikan dalam torsi penyisipan, divergensi, stiffrress, perpindahan, atau beban kegagalan antara 12,5, 15, atau 20 mm panjang cannulated 9mm gangguan dalam tulang babi. Kami percaya, karena itu, bahwa gangguan corre pendek dan sekrup fit dapat digunakan secara klinis di terowongan tibialis tanpa kompromi ing fiksasi graft.

Sekian analisa dari saya, mohon maaf apabila ada kekurangan dalam pemahaman jurnal ini karena saya juga masih dalam tahap pembelajaran. Terima Kasih.