Orthopedics

Feature Article 

Utility of Polymer Cerclage Cables in Revision Shoulder Arthroplasty

T. Bradley Edwards, MD; Kyle D. Stuart, MD; George J. Trappey, MD; Daniel P. O’Connor, PhD; Vineet K. Sarin, PhD

Abstract

Revision shoulder arthroplasty often requires humeral osteotomy for stem extraction or is complicated by periprosthetic fracture. In these situations, various modes of fixation are used, including cerclage wires, cable plates, and allograft strut augmentation. The use of metal wires and cables, however, has been associated with soft tissue irritation, sharps injuries, and accelerated wear of joint arthroplasty bearing surfaces. As an alternative to traditional metal cables, the SuperCable (Kinamed Inc, Camarillo, California) contains braided ultra-high molecular-weight polyethylene fibers surrounding a nylon core. To date, no studies have examined the use of nonmetallic cerclage cables in shoulder arthroplasty.

A retrospective review was performed of 11 patients who underwent shoulder arthroplasty for which nonmetallic cerclage cables were used. Clinical and radiographic data were examined regarding patient age, procedure performed, indication for cerclage cabling, time to healing of osteotomy or fracture, and any complications associated with the use of these cerclage cables. Minimum follow-up was 1 year. Ten patients underwent reverse total shoulder arthroplasty, and 1 patient underwent revision unconstrained total shoulder arthroplasty. Mean follow-up was 20.5 months. Ten patients required humeral osteotomy for stem or cement removal. Allograft augmentation was performed in 7 patients. Mean time to healing was 3.2 months. No patients experienced loosening or migration of hardware or allograft, and no complications directly related to the use of nonmetallic cerclage cables were identified.

Revision shoulder arthroplasty often requires humeral osteotomy for stem extraction or is complicated by periprosthetic fracture.1-6 In these situations, various modes of fixation are used, including cerclage wires, cable plates, and allograft strut augmentation.1,3,7,8 The use of metal wires and cables, however, has been associated with soft tissue irritation, sharps injuries, and accelerated wear of joint arthroplasty bearing surfaces.9-12 Recently, the use of nonmetallic cerclage cables for fixation of osteotomy, intraoperative fracture, and strut allograft was reported in 29 patients undergoing total hip arthroplasty (THA); at an average follow-up of 13 months, 27 of the patients (93%) achieved radiographic healing and there were no observed complications related to the cables.12 To date, no studies have examined the use of nonmetallic cerclage cables in shoulder arthroplasty. This study demonstrates the utility of nonmetallic cerclage cables in revision shoulder arthroplasty.

A retrospective review was performed of 17 patients who underwent revision shoulder arthroplasty with placement of nonmetallic cerclage cables by the senior author (T.B.E.) at a single institution from January 2005 to November 2009. Clinical and radiographic data were analyzed for patient age, sex, procedure performed, indication for cerclage cables, number of cables used, time to clinical healing, and any perioperative complications. Patients were evaluated by clinical examination and radiographs at routine postoperative clinic visits at 2 weeks, 6 weeks, 3 months, 6 months, 12 months, and annually thereafter. A minimum 1-year follow-up was required for inclusion in this study. Four patients were excluded for inadequate postoperative follow-up: 3 patients were lost to follow-up, and 1 patient had not yet reached his 1-year follow-up, which left 13 patients (76%) for review. Mean patient age was 66 years (range, 50-82 years). Mean body mass index (BMI) was 31.82 (range, 19.37-41.71). There were 6 men and 7 women. Mean follow-up was 20.4 months (range, 12-37 months). The Institutional Review Board of Texas Orthopedic Hospital approved this study.

Twelve patients underwent revision of a hemiarthroplasty or total shoulder arthroplasty to a reverse total shoulder arthroplasty. Indications for revision included 2 patients with an infected total shoulder arthroplasty treated with staged revision, 1 patient with a periprosthetic fracture, 4 patients with glenoid component loosening, 1 patient with glenoid erosion, and 4 patients with rotator cuff insufficiency, which included 3 patients with greater tuberosity…

Abstract

Revision shoulder arthroplasty often requires humeral osteotomy for stem extraction or is complicated by periprosthetic fracture. In these situations, various modes of fixation are used, including cerclage wires, cable plates, and allograft strut augmentation. The use of metal wires and cables, however, has been associated with soft tissue irritation, sharps injuries, and accelerated wear of joint arthroplasty bearing surfaces. As an alternative to traditional metal cables, the SuperCable (Kinamed Inc, Camarillo, California) contains braided ultra-high molecular-weight polyethylene fibers surrounding a nylon core. To date, no studies have examined the use of nonmetallic cerclage cables in shoulder arthroplasty.

A retrospective review was performed of 11 patients who underwent shoulder arthroplasty for which nonmetallic cerclage cables were used. Clinical and radiographic data were examined regarding patient age, procedure performed, indication for cerclage cabling, time to healing of osteotomy or fracture, and any complications associated with the use of these cerclage cables. Minimum follow-up was 1 year. Ten patients underwent reverse total shoulder arthroplasty, and 1 patient underwent revision unconstrained total shoulder arthroplasty. Mean follow-up was 20.5 months. Ten patients required humeral osteotomy for stem or cement removal. Allograft augmentation was performed in 7 patients. Mean time to healing was 3.2 months. No patients experienced loosening or migration of hardware or allograft, and no complications directly related to the use of nonmetallic cerclage cables were identified.

Revision shoulder arthroplasty often requires humeral osteotomy for stem extraction or is complicated by periprosthetic fracture.1-6 In these situations, various modes of fixation are used, including cerclage wires, cable plates, and allograft strut augmentation.1,3,7,8 The use of metal wires and cables, however, has been associated with soft tissue irritation, sharps injuries, and accelerated wear of joint arthroplasty bearing surfaces.9-12 Recently, the use of nonmetallic cerclage cables for fixation of osteotomy, intraoperative fracture, and strut allograft was reported in 29 patients undergoing total hip arthroplasty (THA); at an average follow-up of 13 months, 27 of the patients (93%) achieved radiographic healing and there were no observed complications related to the cables.12 To date, no studies have examined the use of nonmetallic cerclage cables in shoulder arthroplasty. This study demonstrates the utility of nonmetallic cerclage cables in revision shoulder arthroplasty.

Materials and Methods

A retrospective review was performed of 17 patients who underwent revision shoulder arthroplasty with placement of nonmetallic cerclage cables by the senior author (T.B.E.) at a single institution from January 2005 to November 2009. Clinical and radiographic data were analyzed for patient age, sex, procedure performed, indication for cerclage cables, number of cables used, time to clinical healing, and any perioperative complications. Patients were evaluated by clinical examination and radiographs at routine postoperative clinic visits at 2 weeks, 6 weeks, 3 months, 6 months, 12 months, and annually thereafter. A minimum 1-year follow-up was required for inclusion in this study. Four patients were excluded for inadequate postoperative follow-up: 3 patients were lost to follow-up, and 1 patient had not yet reached his 1-year follow-up, which left 13 patients (76%) for review. Mean patient age was 66 years (range, 50-82 years). Mean body mass index (BMI) was 31.82 (range, 19.37-41.71). There were 6 men and 7 women. Mean follow-up was 20.4 months (range, 12-37 months). The Institutional Review Board of Texas Orthopedic Hospital approved this study.

Twelve patients underwent revision of a hemiarthroplasty or total shoulder arthroplasty to a reverse total shoulder arthroplasty. Indications for revision included 2 patients with an infected total shoulder arthroplasty treated with staged revision, 1 patient with a periprosthetic fracture, 4 patients with glenoid component loosening, 1 patient with glenoid erosion, and 4 patients with rotator cuff insufficiency, which included 3 patients with greater tuberosity nonunions. One patient underwent revision unconstrained total shoulder arthroplasty for glenoid erosion after hemiarthroplasty. Humeral osteotomy for stem extraction or cement removal was performed for 12 of the 13 patients.

In these cases, cerclage cables were first passed in a subperiosteal fashion using a standard curved passer. The polymer cerclage cables used in this study contain braided ultra-high molecular-weight polyethylene fibers surrounding a nylon core (SuperCable; Kinamed Inc, Camarillo, California). A longitudinal anterior osteotomy directly over the prosthesis or cement mantle was performed with an oscillating saw, and the humeral prosthesis was then removed. To repair the osteotomy, the cables were tensioned sequentially at the high setting, which applies a compressive force of 120 lbs (530 N) at the osteotomy site (Figure 1).13 The cables were then locked with a metal clasp (Figure 2). An allograft strut was used in 9 patients to facilitate osteotomy healing and was placed prior to cable tensioning. Options for allograft included proximal humerus, fibula, tibia, and femur. One patient required cerclage cables for fixation of a proximal humeral allograft for severe proximal humeral deficiency after resection of an infected total shoulder arthroplasty.

Figure 1A: The technique for polymer cerclage tensioning Figure 1B: The technique for polymer cerclage tensioning
Figure 1: Illustration (A) and intraoperative photograph (B) demonstrating the technique for polymer cerclage tensioning around an allograft strut, which is used to augment fixation of a periprosthetic humeral shaft fracture. (Reprinted with permission from Gartsman GM, Edwards TB. Shoulder Arthroplasty. Philadelphia, PA: Saunders; © 2008. Copyright 2008, Elsevier.)

Figure 2A: The final construct appearance of 4 polymer cables Figure 2B: The final construct appearance of 4 polymer cables
Figure 2: Illustration (A) and intraoperative photograph (B) showing the final construct appearance of 4 polymer cables around an allograft strut. (Reprinted with permission from Gartsman GM, Edwards TB. Shoulder Arthroplasty. Philadelphia, PA: Saunders; 2008. Copyright © 2008, Elsevier.)

Healing of the osteotomy or fracture was determined by the absence of tenderness at the fracture or osteotomy site, the presence of osseous bridging, and the absence of component migration, loosening, or hardware failure on serial radiographs (Figure 3).6

Figure 3: A reverse total shoulder arthroplasty
Figure 3: AP radiograph of a reverse total shoulder arthroplasty with a long-stem humeral component surrounded proximally by allograft struts and fixed with 5 polymer cables. The cables are radiolucent but the metal clasps are clearly visualized. (Reprinted with permission from Gartsman GM, Edwards TB. Shoulder Arthroplasty. Philadelphia, PA: Saunders; 2008. Copyright © 2008, Elsevier.)

Results

Among the 13 patients in this study, none demonstrated migration or loosening of the prostheses or cerclage cables at follow-up. The mean number of cables used was 2.7 (range, 1-4). There was no evidence of cable failure in any patient and no complications associated with the use of nonmetallic cerclage cables. No patient showed radiographic or clinical evidence of nonunion. Mean time to clinical healing of osteotomy or fracture was 4.0 months (range, 2-12 months). Clinical information and the results of this study are shown in the Table.

Table 1: Demographics, Clinical Information, and Results of Polymer Cerclage Cables in Revision Shoulder Arthroplasty in 13 Patients

Although no complications were attributed to the cerclage cables, the overall complication rate for revision shoulder arthroplasty was substantial. Seven complications occurred in 6 patients. Three patients treated with reverse total shoulder arthroplasty sustained postoperative dislocations. One was successfully treated with closed reduction and bracing, and another required polyethylene liner exchange. Of note, inspection of the polymer cables during the revision surgery demonstrated no evidence of polymer cable wear or loosening. The third patient sustained multiple dislocations due to frequent falls and remains dislocated at this time. The patient declined revision surgery at last follow-up. Three patients sustained intraoperative fractures during humeral stem removal; 2 fractures involved the greater tuberosity and the other involved the lesser tuberosity. None of the fractures required additional fixation. One patient demonstrated a radial nerve palsy postoperatively, which had resolved by 1-year follow-up.

Discussion

Revision shoulder arthroplasty presents a number of difficulties, often requiring humeral osteotomy for stem removal and posing a high risk for intraoperative fracture.1,4-6,11,14 In these situations, a surgeon can use cerclage wires, cables, cable plates, allograft struts, or other methods of fixation.1,3,7,8 Several studies have reported on the adverse sequelae of using metallic cables in joint arthroplasty and fracture fixation.7,9-11 In the present study, a nonmetallic cerclage cable was used in 11 patients undergoing complex revision shoulder arthroplasty. No complications related directly to the use of this device were noted. Although metallic cerclage cable constructs have not been shown to increase wear in shoulder arthroplasty, their acceleration of polyethylene wear in THA has been well documented.9-11 Given that a model for polyethylene wear in anatomical and reverse shoulder arthroplasty has been reported, a similar phenomenon would be expected to occur in the shoulder.15 The use of nonmetallic cable constructs would, theoretically, decrease the risk for polyethylene wear and subsequent glenoid or humeral component loosening.

Other advantages of this device include the ability to retension even after placing the locking clips, the absence of sharp ends that are present on some metallic cables that can cause tissue irritation or surgeon injury, and its favorable biomechanical properties.4,12 Laboratory testing shows a similar ultimate strength when compared to metallic cables and superior fatigue strength.4 Tensile strength is approximately 250 lbs (1110 N), and fatigue testing showed no failures after 1 million cycles at 100 lbs (445 N).4 Also, fraying and fretting of metallic cables, which produces debris, is associated with fatigue failure of these devices. This type of wear does not occur with the polymer cables; wear and abrasion between the polymer cables and the metal clips was evaluated in laboratory testing using high-resolution microscopy after 1 million cycles of fatigue loading and was found to be negligible.4 In this study, radiographs showed no migration of the polymer cables nor any evidence of cable breakage or loosening. Although the cables are radiolucent, the metal clips are radiopaque and easily visualized. Lastly, the cost of these nonmetallic cables is equivalent to the metal cables already in use at our institution.

Healing of the humeral osteotomy and periprosthetic fractures in this cohort of patients was not deterred by the polymer cables. Mean time to clinical healing was 4 months. This approximates the time to union reported by other studies with regard to periprosthetic humeral fractures and humeral osteotomies.6,8 The use of allograft struts has been shown to augment healing in both humeral nonunions and in periprosthetic fractures of the femur and is recommended for these complex cases.14,16

Complications associated with revision shoulder arthroplasty include dislocation, component loosening or failure, infection, fracture, and the need for further surgical procedures. Six patients in this study encountered complications. At 1-year follow-up, however, only 1 patient showed an unsatisfactory clinical outcome.

The low prevalence of revision shoulder arthroplasty compared to revision hip or knee arthroplasty limited the power of this study. A far greater number of patients and multicenter sampling would be required to perform a randomized comparison of metallic and nonmetallic cables in this patient population. Nevertheless, it is important to note that none of the 28 cables used in this study were directly associated with intra- or postoperative complications. In fact, among all cases performed by the senior author with this device, no direct complications from its use have occurred. Ting et al12 also reported no complications related to the use of these cables at an average postoperative time of 13 months in 29 patients undergoing reconstructive THA, including 7 patients undergoing revision THA following deep periprosthetic infection.

Conclusion

This study indicates that polymer cerclage cables provide a safe and effective method of fixation for periprosthetic fractures and humeral osteotomies in revision shoulder arthroplasty.

References

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  2. Jouve F, Walch G, Wall B, Edwards TB. Humeral osteotomy in revision shoulder arthroplasty. Tech Shoulder Elbow Surg. 2006; 7(2):106-110.
  3. Lo IK, Bishop JY, Flatow EL. Revision shoulder arthroplasty after failed total shoulder arthroplasty. Oper Tech Orthop. 2003; 13(4):277-289.
  4. Sarin VK, Mattchen TM, Pratt WR, Hack B. Novel iso-elastic cerclage cable for fracture treatment. J Bone Joint Surg Br. 2008; 90(suppl 1):189.
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Authors

Dr Edwards is from Fondren Orthopedic Group LLP, Texas Orthopedic Hospital, Houston, Dr Stuart is from the Department of Orthopedic Surgery and Rehabilitation, University of Texas Medical Branch, Galveston, Dr Trappey is from the Shoulder and Elbow Fellowship, Texas Orthopedic Hospital, Houston, and Dr O’Connor is from the Laboratory of Integrated Physiology, University of Houston, Houston, Texas; and Dr Sarin is from Kinamed, Inc, Camarillo, California.

Dr Edwards is a consultant to Kinamed, Inc. Drs Stuart, Trappey, and O’Connor have no relevant financial relationships to disclose. Dr Sarin is President of Kinamed, Inc.

Correspondence should be addressed to: T. Bradley Edwards, MD, Texas Orthopedic Hospital, 7401 S Main St, Houston, TX 77030 (bemd@fondren.com).

doi: 10.3928/01477447-20110228-13

10.3928/01477447-20110228-13

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