Cannulated screw unraveling: a case series and literature-based review of an under-recognized complication

Abstract

Partially threaded cannulated screws have enhanced the orthopedic surgeon's ability to fix periarticular fractures. There are many reports of complications and hardware failure during screw removal, but those during fracture fixation are under-reported and under-recognized in the literature. We describe a 21-year-old healthy man with a grade 1 open displaced medial epicondylar humerus fracture. Upon fracture fixation in the OR using a partially threaded cannulated screw over a Kirschner wire, the threads of the screw unraveled. The operating surgeon felt increased resistance and the unraveling was demonstrated on intra-operative fluoroscopy. The screw was removed by hand without hardware retention and a new K-wire and cannulated screw were used for definitive fixation. We found seven previous cases reporting a similar complication with mixed presentations and results. All occurred in young healthy patients, six of which were males. Six of the seven cases made no mention of a tactile change in resistance during fixation and only one of the seven pre-drilled the cortex prior to placement of the cannulated screw. We believe that screw unraveling is an under-reported complication of fracture fixation with cannulated screws that should be recognized by the orthopedic community. We found intra-operative fluoroscopy integral to the recognition of the problem in our case and recommend its use in fracture fixation with cannulated screws. We also suggest pre-drilling of cortices, especially when operating on young patients with strong bone.

Unwinding of a 4.5 mm partially threaded cannulated screw in an elderly patient: A case report

“…Partially threaded, cannulated cancellous screws are applicable in a variety of fracture patterns but appear to have an increasingly reported mechanical fault. There have been previous reports of the screw unwinding with insertion through dense cortical bone in young patients but our case occurred in an older patient through cancellous bone [1,2] .…”

“…The study by Kupperman et al revealed that this complication occurred in young males with dense bone in either the humerus, tibia or cuneiform. It was reported that 75% of cases documented no change in resistance when inserting the screw, only 50% of the defective screws were successfully removed and 25% of screws were left in without attempted removal 2 . Our case is unique in that our patient was elderly and it involved cancellous bone in the scapula.…”

Thread Delamination in 4.5 mm AO Cannulated Screws: A Small Case Series in the Pediatric Trauma Population

“…Kupperman et al 9 have previously summarized 8 cases of cannulated screw unraveling, including 7 cases in 5 previously published studies and 1 single case from their own institution. These cases were of majority male patients (7/8; 88%), included a range of patient ages from 12 to 38 years, as well as involved multiple anatomic locations, including the proximal and distal humerus, proximal and distal tibia and the medial cuneiform.…”

“…2 , 3 Furthermore, isolated case reports have described a unique complication in the form of thread failure with screw unraveling. 4 – 9 …”

Arthroscopic Reinsertion of Lateral Collateral Ligament, Anterior Capsular Plication, and Coronoid Tunneling Technique for Chronic Elbow Posterolateral Rotatory Instability

“…Our technique does not need the use of screws for soft-tissue fixation and does not include harvesting and use of tendon grafts, differently from other techniques, avoiding all the related complications. 9,10 It also enables a reconstruction as anatomic and minimally invasive as possible; this allows patients to have a rapid recovery, and they are able to return as soon as possible to the activities of daily living. 11 Moreover, an arthroscopic approach allows the surgeon to identify and treat minor injuries, such as a lesion of the articular portion of the radial collateral ligament or the annular drive-through, that would not be identifiable with an open procedure.…”