Absorbable Screw Fixation - The Podiatry Institute

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$closure of deep fascia in ankle fracture surgery - The Podiatry Institute$

CFIAPTER 11 63fusion techniques with metallic fixation that requireprolonged periods of non-weight bearing.However, the pertinence of stress-shielding orstress-protection osteopenia in forefoot surgery islikely more procedure specific. For example, in thetechnique of hallux interphalangeal joint fusion,the absorbable screw does not seem advantageous.Stress shielding at this site is minimal, and if screwremoval is necessary, it is easily performed underlocal anesthesia. Metallic flxation also subjectivelyoffers firmer purchase and compression in theproximal phalanx than the absorbable screws.However, the forces acting upon a first metatarsalproximal osteotomy or a midfoot fusion are signiticantlylarger due to the unique biomechanics of thefoot in gait. The reduction of stress shieldingafforded by the less rigid absorbable screws mayencourage more rapid and solid osseous consolidationin these applications, similar to the successnoted in ankle fusions.Absorbable screws do contribute a potentialsoft tissue complication that must be clearly understood.This transient soft tissue reaction has beenextensively studied since it was first noted with theearly development of polyglycolide rods.3 Theexact reason for the reaction is unknown, butappears to be a unique foreign body reaction to theraw materials, alpha-hydroxy polyesters. Currently,there is no evidence that the reaction is immunologicallymediated or infectious in nature. A lowerincidence has been reported since the removal ofthe aromatic quinone (green) dye from the firstgeneration polyglycolide rods and screws, but thisis also clearly not the only factor. Since the adventof the colorless raw materials used to make thescrews, the reported incidence of tissue reactions isless than 4ol0.'The development of a clinically manifestedreaction seems to be associated with the phase ofliquefaction of the degrading polymer.'O The clearanceof liquid debris from the implant depends onlocal tissue tolerance and clearing capacity.,, Therelatively compact nature of cancellous bone maybe a factor. Surgical technique may also play a role,such as when a large amount of screw head is leftabove the cortex in an area where soft tissuecoverage is thin.In general, reactions to the PLLA implants arereported less often. However, reactions have beenseen with PLLA implants approximately 4 yearsafter surgery." The longer degradation time andassociation befween clinical reaction and liquefactionphase of the implant may be a factor.Interestingly, the follow-up review of most articlesrarely approaches four years, which theoreticallymight affect the number of reported reactions.Lastly, PLLA raw material from varying sources candiffer considerably in thermal history, molecularweight, and crystallinity, resulting in differentdegradation patterns and tissue responses.The actual tissue reaction may vary from localerythema that resolves in a few days to a sinus tractformation which requires surgical debridement.The incidence of sinus tract formation may bedecreased or prevented by aspirating or incisinglocal fluid accumulations. The reactions are apparently manageable without difficulty, and do notinfluence the functional recovery in any way. Theauthors have not had any experience with thesereactions to date. It should be emphasized thatreports in the podiatric literature of reactions toBIOFIX material were with the use of PGA pins,and prior to the removal of the green dye.","Final observations are that the screws areradiolucent, and thal the amount of interfragmentarycompression seems less than that which isattainable with metallic fixation. Both factors maybe disconcerting to surgeons accustomed to standardAO/ASIF techniques and materials (Figs. 6A,Figure 6A. Preoperative x-ray of a moderateseverehallux valgus deformity.
64 CHAPTER 1168). The radiolucency is a drawback in those procedureswhere confirmation of position of fixationis desirable. More reliance on the position of temporaryflxation and the technical execution of theprocedure may be necessary. The obtainable interfragmentarycompression is a product of screwdesign and the operative technique recommendedby the manufacturers. Howevel the more pefiinentissue is whether the compression is adequate.Clinical studies clearly indicate that the difference inbiomechanics of these implants, as compared withmetallic screws, does not affect the radiographic orclinical outcome in the recommended uses.Figure 68. Immediate postoperative x-ray of halluxvalgus correction via a transpositionalproximal osteotomy. The SR PLI.A 3.5-mm screwused for flration is completely radiolucent.The only absorbable screw available for clinicaluse in the United States at this time is the SR-PGA4.5-mm fully-threaded screw. The literature supportsits immediate use in ankle fracture repair. It is particularlywell-suited to trans-syndesmotic fkationdue to its relatively shofi strength duration and theelimination of a second procedure for fixationremoval. The indications and uses of absorbablescrews will expand in the ensuing years as othersizes and the SR-PLLA screws are released. Theyrepresent an exciting option in the selection of internaltixation devices currently avallable. Appropriateindications in podiatric surgery will require objectiveevaluation of matters such as those discussed here,and other factors elucidated by present and futurescientific research.6789101112.L3.74REFERENCESPartio EK: Absorbable screws in the firation of cancellous bonefractures and arthrodesis. A clinical study of 318 patients.Academic dissefiation, from the Depafiment of Othopaedics andTraumatology, Helsinki University Central Hospital, Helsinki, 1992.Pafiio EK, Bostman O, Hirvensalo E, et al.: Self-reinforcedAbsorbable Screws in the Fixation of Displaced Ankle Fractures.A Prospective Clinical Study of 152 Patients J Ortbop Trauma5:209-215,1992.Biofix-Tissue Management Systems, Implantes reabsorbiblesauto-reforzados de acidos poliglicolido (SR-PGA) y polilactido(SR-PLIA), para la fijacion de fracturas. (product information)Bioscience Limited, Tampere, Finland.Tormrilzi P. Vasenius J, Vainionptii S et a1.: Ultra-high-strengthabsorbable self'-reinforced polyglycolide (SR-PGA) compositerods for internal fkation of bone fractures: In vitro and in vivoswdy. J Biomed Mater Res 25:1.-22, 791)7.Biofix, Absorbable Self-Reinforced Tissue Management Implants,lYorksbop Trdining Manual, Part III, Full Tlcreacl Screus JbrOrthopaedics and Traumatology. Bioscience Limited, Tampere,Finland, 1992.Manuscript for the Bioflr sales aid, Bioscience Limited, Tampere,Finland. 1994.Bostman O, Pafiio EK, Hirwensalo E, Rokkanen P: Foreign bodyreactions to polyglycolide screws. Observations io 24/2L6 malleolarfracture cases. Acta Orlhop Scand 63173-176,1992.Pafiio EK, Hirvensalo E, Pafiio E, et al.; Talocn:ral Arthodesiswith Absorbable Screws. Acta Ofihop Scand.53:170-172, 1992.Pafiio EK, Merikanto J, Heikkia JT, et a1.: Totally absorbablescrews in the firation of subtalar extra-articular arthrodesis inchildren with spastic neuromuscular disease. J Pediatr Ortbop \21646-6i0, 1992.Pihlajamziki H, Bostman O, Hirvensalo E, et a1.: Biodegradablepolylactide pins in the fl\ation of fractures and osteotomies.XXWI World Congress of the Intemational College of Surgeons,Bologna, Italy, Monduzzi Editore, 1992, pp 617-621,1992.Suuronen R, Laine P, Sarkial E, et a1.: Sagittal split osteotomyfixed with biodegradable, self-reinforced poly-L-lactide screws. Apilot study in sheep. Int J Orul M.lxillcfac Surg 21,:303-308, 7992.Rozema FR, Bos RRM, Boering G: Late tissue response to bonepaltes and screws of poly (LJactide) used for firation of zygomaticfractures: report of 4 cases. Proc 9tb Europe.4n Conferenceon Bionxaterials Chester, 1991, p 151.Parks RM, Nelson G: Complications with the use of bioabsorbablepins in the fctc;t. J Am Podiatr Med Assoc 32(2):153-167,1.993.Johnson JD: Adverse reaction to absorbable rods.(letter to theeditoi) J Am Podidtr Med Assoc 83(]):427-128, 1993.
Page 2 and 3: CHAPTER 11 59threaded, whereas the
Page 4 and 5: CHAPTER 116IFigure 38. Heacl profil
Page 8: CHAPTER 11 65ADDITIONAL REFERENCESA

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