Fixation with a Cannulated Screw Displaced Scaphoid Fractures ...

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$Immediate internal fixation of open ankle fractures. Report$

$4.9 Malleolar fractures$

DISPLACED SCAPHOID FRACTURES TREATED WITH OPEN REDUCTION AND INTERNAL FIXATION 639ated with slower healing at the 95 percent confidencelevel in both groups (p < 0.01). Fractures in patients whosmoked healed at an average of 5.2 months comparedwith 3.5 months in patients who did not smoke.Because the duration of follow-up was different ineach of the groups, a Kaplan-Meier 17 estimate was usedto evaluate the difference in the time to union betweenthe two screw types; there was no significant difference,with a power of 0.8. A shorter time to union was associatedwith greater grip strength and with a better rangeof motion of the wrist in both groups (p < 0.05). An increasein the time to union was correlated with increasingage of the patient (r = 0.665) and with increasingpreoperative displacement of the fracture (r = 0.541).The use of bone graft correlated with increasing time tounion (p < 0.05), which may represent preselection ofpatients with a more severe injury (with comminution),as all patients who received bone graft had comminutionnoted at the time of surgery. The time to union didnot correlate with the lateral intrascaphoid angle, anteroposteriorintrascaphoid angle, or height-to-lengthratio on preoperative radiographs. There was also nocorrelation between the time to union and gender orhand dominance.Postoperatively, the average total range of motionon the involved side was 86 ± 8 percent of that on thecontralateral side in Group 1; the patients had an averageof 120 ± 16 degrees of flexion-extension of the wristand 35 ± 10 degrees of radioulnar deviation. These resultsare similar to those in Group 2, in which the rangeof motion was 86 ± 7 percent of that on the contralateralside and the patients had an average of 113 ± 16 degreesof flexion-extension of the wrist and 35 ± 6 degrees ofradioulnar deviation. There was no significant differencein the range of motion between the two groups.Logistic regression analysis with adjustment for clinicaland radiographic variables showed that an increasingpostoperative range of motion correlated with a decreasinglateral intrascaphoid angle (r = 0.625) and a decreasingscaphoid height-to-length ratio (r = 0.584).Postoperatively, the patients in Group 1 regained an averageof thirty-eight kilograms of grip strength, or 80 ±11 percent of the strength on the contralateral side. Thepatients in Group 2 regained an average of forty-two kilogramsof grip strength, or 79 ± 16 percent of thestrength on the contralateral side. Twenty-eight patientswho were employed preoperatively returned to theirprevious occupation after the surgery.ComplicationsTwo of the patients treated with an AO/ASIF cannulatedscrew had symptoms related to a prominentscrew-head after union of the scaphoid. One patient ineach group had pain and irritation related to a prominentwire, requiring early removal of the wire. Only onepatient, in Group 1, had evidence of partial avascularnecrosis (stage 1) at the final follow-up examination.One patient in Group 1 and one in Group 2 had osteoarthritis(stage 1 in both) by the time of the final follow-upevaluation. None of the patients in either group hadsymptoms that limited their ability to work. Three patientsin Group 1 noted slight pain with strenuous activities(grade 1), as did two patients in Group 2. There wasno significant difference in terms of pain at work or duringstrenuous activity between the groups (p < 0.05).DiscussionMost reports regarding scaphoid fractures have focusedon nonunions. Herbert and Fisher 16 reported a 100percent rate of union following the treatment of 158acute displaced fractures of the waist of the scaphoid.We are not aware of any published reports that have includedpatients treated with cannulated screws. In thepresent retrospective study, we evaluated the results oftreatment with two different cannulated screws. We hadinitially used the cannulated AO/ASIF screw because itwas the first screw available on the market that met thedesign parameters needed to treat scaphoid fractures.Because of problems related to the prominent screwheadin some patients in a previous study 25 on the use of3.5-millimeter cannulated AO/ASIF screws for treatmentof scaphoid nonunion, we have subsequently preferredthe double-threaded Herbert-Whipple screw,which is a cannulated screw specifically designed for thetreatment of scaphoid fractures. Although Stark et al. 24noted an improvement in the scapholunate angle aftertreatment of scaphoid nonunion with Kirschner wiresand bone graft, we know of no reports of improvementin scaphoid alignment as assessed with measurement ofthe intrascaphoid angle or the scaphoid height-to-lengthratio after treatment of scaphoid fractures or nonunionswith internal fixation devices.The rate of union in the present study was 100 percentfor both groups of patients. This success rate ismost likely attributable to our strict inclusion criteria,which enabled us to select an ideal group of patients. Weexcluded patients who had a fracture of the proximalpole, osteoarthritis, or carpal instability, all of whichhave been associated with a decreased rate of union 7,23 .Manske et al. 19 demonstrated that the use of a Kirschnerwire in addition to a screw controlled the rotation of thefracture fragments and improved both the time to unionand the rate of union after treatment of scaphoid nonunion.Therefore, we incorporated this technique intoour treatment of acute displaced scaphoid fractureswhen comminution was present.Because it is difficult to design a comparative studyin which the number of patients is large enough for therate of union to be used as the end point, we studied thetime to union as confirmed by computerized tomography.The importance of using tomography for thispurpose was demonstrated by Cooney et al. 8 , who foundthat patients managed with screw fixation who werethought to have a healed nonunion on the basis of plainVOL. 82-A, NO. 5, MAY 2000
640 T. E. TRUMBLE, MARY GILBERT, L. W. MURRAY, JEFFERY SMITH, GREG RAFIJAH, AND W. V. MCCALLISTERradiographs often needed another bone-grafting procedurebecause of persistent instability. In another study 7 ,they used a variety of techniques, including Kirschnerwires, in forty-four patients in whom volar inlay graftswere placed, and the time to union averaged eighteenweeks. Stark et al. 24 reported an average time to union ofseventeen weeks in 147 of 151 patients who had fixationwith Kirschner wires in addition to bone-grafting fornonunion of the scaphoid. In the present study of patientswith acute fractures, the average time to unionwas 4.1 ± 1.2 months (range, 2.8 to 8.0 months), althoughit usually took one month longer to identify ascaphoid union with use of computerized tomographyscans than with use of plain radiographs.The number of patients who were smoking duringthe treatment was small. Nevertheless, as noted in reportson lower-extremity injuries 4,5,15 , smoking was foundto have a significant effect on fracture-healing. Regardlessof the type of screw used, the time to union was increasedin patients who smoked. The mechanism bywhich smoking affects fracture-healing is unknown.The functional results in terms of grip strength andrange of motion in our study compare very well withthose in reports involving nonunions of the scaphoid, althoughthere is very little information on the functionalresults following internal fixation of acute fractures. It isdifficult to compare some of the studies of fractures andnonunions of the scaphoid because the results were notnormalized as a percentage of the contralateral side. Althoughexact numbers were not given, Herbert andFisher 16 and Filan and Herbert 13 reported a recovery ofgrip strength of more than 90 percent compared withthat on the contralateral side. With use of a Jamar dynamometerto measure grip strength, we noted an averagerecovery of 79 percent compared with that on the contralateralside.The range of motion after internal fixation with orwithout bone-grafting was reported as a percentage ofthat on the contralateral side. In the present study, weobserved an average total flexion-extension arc of 89percent of that on the contralateral side and an averageradioulnar deviation of 76 percent of that on the contralateralside. Filan and Herbert 13 noted that their patientsregained more than 90 percent of the normalrange of motion of the wrist, although specific valueswere not given. We are not aware of any other studies inwhich the range of motion was measured and comparedwith the range on the uninjured side after internal fixationof acute scaphoid fractures. In studies of scaphoidnonunions treated with screw fixation, the range of motionhas varied from a flexion-extension arc of 67 percentand a radioulnar deviation of 55 percent 1to aflexion-extension arc of 84 percent and a radioulnar deviationof 76 percent 25 .Another finding in our study, similar to that in otherreports, was the relief of pain. Of the thirty-five patientswhom we treated, only five (14 percent) continued tohave occasional mild pain. These results correspondwell with those reported by Filan and Herbert 13 , whonoted that 14 percent of 431 patients had an unspecifieddegree of pain at the time of the latest review. Cooney etal. 6,7 noted that fourteen (21 percent) of sixty-eight patientsin whom a scaphoid nonunion had healed continuedto have occasional mild pain.None of the reports that we reviewed provided specificvalues for preoperative and postoperative intracarpalangles in patients treated for an acute displacedscaphoid fracture. One of the major factors associatedwith the results in our study was improvement in thealignment of the scaphoid. Amadio et al. 2 noted that patientswho had a malunion of the scaphoid had a twofoldincrease in the prevalence of osteoarthritis; however, amultivariate regression analysis showed no associationbetween a postoperatively corrected scapholunate angleand an increased prevalence of osteoarthritis, presumablybecause very few patients had an abnormalscapholunate angle either before or after the surgery.Preoperatively, all of our patients had collapse of thescaphoid with alteration of the anteroposterior intrascaphoidangle, the lateral intrascaphoid angle, or theheight-to-length ratio of the scaphoid. We found thatpatients with more correction of the lateral intrascaphoidangle or the scaphoid height-to-length ratiohad more postoperative wrist motion, possibly indicatingthat the mechanics of the wrist were improved as thescaphoid alignment and height were restored to normal.There were several weaknesses in our small retrospectivestudy on acute scaphoid fractures. The patientdata were provided by a team of different physiciansand medical staff, the surgical procedures were performedsequentially by different doctors, and the implantswere not randomized for the purpose of thisstudy.Despite the inherent limitations of our study, weconcluded that fixation with use of either the AO/ASIFor the Herbert-Whipple cannulated screw is an effectivetechnique for the internal fixation of displaced fracturesof the waist of the scaphoid.References1. Adams, B. D.; Blair, W. F.; Reagan, D. S.; and Grundberg, A. B.: Technical factors related to Herbert screw fixation. J. Hand Surg., 13A:893-899, 1988.2. Amadio, P. C.; Berquist, T. H.; Smith, D. K.; Ilstrup, D. M.; Cooney, W. P., III; and Linscheid, R. L.: Scaphoid malunion. J. Hand Surg., 14A:679-687, 1989.3. Bain, G. I.; Bennett, J. D.; MacDermid, J. C.; Slethaug, G. P.; Richards, R. S.; and Roth, J. H.: Measurement of the scaphoid humpback deformityusing longitudinal computed tomography: intra- and interobserver variability using various measurement techniques. J. HandSurg., 23A: 76-81, 1998.THE JOURNAL OF BONE AND JOINT SURGERY
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Fixation with a Cannulated Screw Displaced Scaphoid Fractures ...

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