Should Implant Breakage Be Always Considered as Implant “Failure” in Spine Surgery: Analysis of Two Cases and Literature Review

Abstract

The advancement in the material of spinal implant and technique of spinal instrumentation has led to an increase in spine surgeries. The final desired outcome of spine surgery involving instrumentation is fusion. There is a race among implants to fail and bone to fuse. If there is a formation of pseudoarthrosis or failure to fuse then implants are bound to fail. The most common presentation of pseudoarthrosis is implant breakage. Hence, should we label every implant that has presented with breakage as a "failure"? In this article, we have discussed our experience of two cases presented to us with implant breakage but which were managed successfully with conservative methods. Both of our cases did well without any surgical intervention. We have follow-ups of seven years in one case and five years in the other. Every patient with pseudoarthrosis does not require surgical management and hence, every implant breakage should not be labeled as implant "failure".

Posterior spinal implant failure and its clinical significance: analysis of two cases and literature review

“…9 Implant failure occurs most frequently within the first 6 months post-surgery (90% of cases), caused by several factors, among the most common are pseudoarthrosis or failure of fusion and design of devices; some multicenter studies showed that up to 6.8% of patients suffered this type of complication referring to rod breakage as the most frequent presentation. 8,10,11 The incidence of pseudoarthrosis is observed in 3-83% (average 24%), mostly found in the transition sites, and mainly affecting the thoracolumbar region; [11][12][13][14] this process demonstrates a continuous tension on the implants, leading to fracture or loosening of the instrumentation. 10 The series of Hofler et al 15 and How et al 16 reported a 1.4% to 6.3% risk of developing pseudoarthrosis that required revision surgery depending on the main disease (long instrumentation, spinal deformity respectively).…”

“…8,10,11 The incidence of pseudoarthrosis is observed in 3-83% (average 24%), mostly found in the transition sites, and mainly affecting the thoracolumbar region; [11][12][13][14] this process demonstrates a continuous tension on the implants, leading to fracture or loosening of the instrumentation. 10 The series of Hofler et al 15 and How et al 16 reported a 1.4% to 6.3% risk of developing pseudoarthrosis that required revision surgery depending on the main disease (long instrumentation, spinal deformity respectively). This complication stems from two causes: surgical and non-surgical.…”

“…On the other hand, the absence of neurological symptoms and pain are important characteristics for the treatment decision, being surveillance and medical management the ideal treatment in these cases. 10 There are currently many techniques for the removal of the affected implants, if the broken screw fragment is inside the pedicle, it can be extracted by drilling the screw; 7 if there isn't enough space in perpendicular position for the insertion of a new screw, it can be treated by drilling at the inferomedial point of the pedicle for a new placement (of a longer screw with a larger diameter, without exceeding a 70% of the treated pedicle diameter to avoid its rupture), treating it below the broken fragment (above L5 levels) 7,12,14,18 or a making a vertebral spinal fusion bridge of the affected level; in some cases where S1 screw fatigue is found, a similar technique can be performed with the removal of the screw after its drilling until the broken surface of the screw is discovered and can be removed with a screwdriver and reposition another one into an anteromedial or tricortical direction towards the sacral promontory. If the screw cannot be removed in this segment, 1) place an anteromedial screw directed to the broken screw (this will depend on the direction of the first screw) 2) Avoid the S1 pedicle and insert the screw in the sacral alar or 3) placement of iliac screws.…”

Unique Procedure to Remove Pedicle Screw without Compatible Instrumentation: Case Report and Review of Literature

“…After the 1940s, the implant material and implant techniques have gone through considerable changes due to which they can resist the continuous stress of weight-bearing, flexion, and extension until fusion occurs. The most common reason for implant failure is unsuccessful fusion [ 2 ]. There is a race between implant failure and union and if union does not occur, there are high chance that patient will land up in implant failure which can be in the form of hardware fracture, loosening of screws, and screw pullout [ 3 ].…”