Biomechanical Study On V-Y Extending Terminal Tendon Of Extensor Tendon For Distal Attachment In Human Cadaver Hands

Objective:To discuss biomechanics of V-Y extending Terminal Tendon(TT)for distal attachment to treat chronic mallet fingers(tendon-bone or partial bony).Methods:15 fingers were randomly divided into two groups based upon the repair technique: the control group: 1mm TT was removed at the insertion,the distal TT was sutured by Krackow and attached by pull-out;the experimental group: 1mm TT was removed at the insertion,the proximal portion of the TT by making a ?V? incision which was then repaired in a ?Y? fashion,and the distal TT was sutured by Krackow and attached by pull-out.The repair failure force,maximum displacement,both load and displacement at 1mm gap of the tendon-bone were recorded,and stiffness was calculated and statistically analyzed.Results:As the rupture(load failure)occurred,the experimental group : 2 specimens failed by suture breakages and 5 cases failed by suture pulled out from the tendon at V-Y suture,no knots slipped;all sutures were prolonged at attachment,no suture breakages,no suture pulled out from the tendon,no knots slipped.Suture breakages happened in all specimens of the control group,no suture pulled out from the tendon,no knots slipped.The repair failure force and the maximum displacement of experimental group were 9.630 N and 10.191 mm,while 19.932 N and 12.896 mm in the control group,There was significant difference between the two groups(P<0.05)in the load failure while no significant difference(P>0.05)in the maximum displacement.All sutures were pulled out from the tendon at the attachment when the tendon-bone gap reached 1mm in both groups,no suture breakages,no knots slipped and no suture pulled out from the tendon.The tendon-tendon was closely sticked and no suture breakages,no knots slipped and no suture pulled out from the tendon at V-Y suture.The displacement of the experimental group was 6.615 mm while 4.407 mm in the control group,There was significantly different between the two groups(P<0.05).The load and stiffness of the experimental group were 4.376 N and 1.431 N/mm while 3.245 and 1.788 N/mm in the control group,There was no significant difference between the two groups(P>0.05).Conclusion:The load,displacement and stiffness of tendon-bone gap reached 1mm were more meaningful and accurately to evaluate mallet finger recurrence than the repair failure force and maximum displacement.V-Y suture effectively extended TT and repaired tendon-bone gap,while unaffecting the biomechanical properties of TT.Also tendon grafts were unnecessary,reducing secondary trauma and cost of patients.It can be used in tendon-bone type or partial bony(needing to cut off the bone pieces and reconstruct insertion)mallet fingers.