The Flint Lock: A Novel Technique in Total Knee Arthroplasty Closure
Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article.
Dr. Peck is an Orthopedic Surgery Fellow, Hospital for Special Surgery, New York, New York. Dr. Charpentier is an Orthopedic Surgeon, Howard Memorial Hospital, Willits, California. Dr. Srivastava is Associate Professor, Department of Orthopedic Surgery, McLaren-Flint/Michigan State University, Flint, Michigan. Ms. Bowman is a Nurse Practitioner, Department of Orthopedic Surgery, Hurley Medical Center, Flint, Michigan.
Address correspondence to: Jeffrey B. Peck, MD, Center of Hip Preservation, Hospital for Special Surgery, 535 E. 70th St, New York, NY 10021 (tel, 847-702-1589; fax, 810-342-2150; email, JeffreyPeck2007@u.northwestern.edu).
Am J Orthop. 2018;47(9). Copyright Frontline Medical Communications Inc. 2018. All rights reserved.
Conventional interrupted sutures are traditionally used in extensor mechanism closure during total knee arthroplasty (TKA). In recent years, barbed suture has been introduced with the proposed benefits of decreased closure time and a watertight seal that is superior to interrupted sutures. Complication rates using barbed sutures and conventional interrupted sutures are similar. We propose a novel closure technique known as the Flint Lock, which is a double continuous interlocking stitch. The Flint Lock provides a quick and efficient closure to the extensor mechanism in TKA. In addition, similar to barbed suture, the Flint Lock should provide a superior watertight seal. It utilizes relatively inexpensive and readily available materials.
- The Flint Lock is a novel technique in TKA closure.
- Its continuous nature provides a tight seal with extensor mechanism closure.
- The utilization of a segmental closure with double suture provides a safeguard for suture failure.
- The suture used in the technique is less expensive than barbed suture.
- Future investigation is warranted to further validate the use of the Flint Lock.
In 2003, more than 400,000 total knee replacements were performed in the United States. This number is expected to increase in the coming decades to 3 million by the year 2030.1 The surgical approach to knee arthroplasty always involves a capsular incision that needs to be repaired after implantation of the components. The capsular incision repair should be strong enough to allow for immediate range of motion.
Traditionally, repair of the arthrotomy is performed using interrupted sutures. Recently, a running technique using barbed suture has been demonstrated to enable faster closure times.2-6 In addition, a running suture technique using barbed suture provides a superior watertight closure compared with an interrupted suture.7 It has been reported that the barbed suture has the same safety profile as that of interrupted sutures,2,3,4 although extensor mechanism repair failure8 and wound complications9,10 have been reported.
This study proposes a novel technique for arthrotomy closure in total knee arthroplasty (TKA). It is a double continuous interlocking stitch, termed the “Flint Lock.” Based on our clinical experience using this method, this technique has been found to be safe and effective.
The Flint Lock was developed for closure in TKA, which was performed through a standard medial parapatellar approach. Before creating the arthrotomy, a horizontal line is drawn along the medial side of the patella to ensure anatomic alignment of the extensor mechanism during closure of the capsule.
The Flint Lock is performed by 2 people working simultaneously. Closure begins at the proximal end of the arthrotomy using 2 No. 1 Vicryl (Ethicon) sutures. Each suture is thrown a single time at the most proximal extent of the arthrotomy with the knee in 30° to 40° of flexion. These sutures are tied off independently from each other (Figure 1). At this point, the knee is flexed to 90° and the sutures are thrown alternately, with the first operator passing medial to lateral through the capsule and the second operator passing lateral to medial. While 1 operator is passing a suture, the other operator holds the other suture tight to maintain tension on the closure. The alternating throws create an interlocking weave as the pattern is repeated and progressively moves distally (Figure 2). This technique results in 2 continuous sutures running in opposing directions. Each No. 1 Vicryl suture is specific to each operator. Therefore, each operator uses the same suture for the entirety of the closure.
When the superior pole of the patella is reached, the 2 sutures are tied together, thus creating a segmental closure (Figure 3). Following this tie off, the closure is continued in a similar manner until the inferior pole of the patella is reached. The sutures are then tied off to each other again, creating another segmental closure (Figure 4). The remainder of the arthrotomy is closed continuing the Flint Lock technique, and the 2 sutures are tied off to each other at the distal end of the arthrotomy and cut (Figure 5).
The superficial layers are closed at the surgeon’s discretion. The authors prefer interrupted 2-0 Vicryl sutures followed by a running 3-0 Monocryl (Ethicon) suture in the subcutaneous layer. Dermabond (Ethicon) skin glue and an Aquacel Ag (ConvaTec) dressing are applied, followed by a compressive bandage.
The importance of a strong, tight closure of the arthrotomy in TKA is critical to the success of the procedure. Nevertheless, there are multiple methods to achieve closure. The Flint Lock technique is a novel method that employs basic concepts of surgical technique in an original manner. The continuous nature of the closure should provide a tighter seal, leading to less wound drainage. Persistent wound drainage has been associated with deep wound infections following total joint arthroplasty.11,12 In addition, the double suture provides a safeguard to a single suture rupture, while the segmental quality protects against complete arthrotomy failure.
A potential downside of this technique is that it requires 2 individuals operating 2 needles simultaneously. This presents a potential for a sharp injury to the operators; however, this has not occurred in our experience. A comparable risk with interrupted sutures is probably present because there are often multiple sutures utilized during closure via the interrupted technique.
In 2015, the cost of a single No. 1 barbed suture was $13.14 at our institution, whereas the cost of 2 No. 1 Vicryl sutures was $3.66. Although pricing differs across hospitals, the Vicryl sutures are probably less costly compared with the barbed sutures.
Our experience with the Flint Lock technique has been favorable thus far, with no incidences of postoperative drainage, infection, or extensor mechanism failure. Our current use has been in closure of the knee, but it could be considered in closure of long incisions about the hip as well. A more in-depth analysis of relevant factors, such as time for closure, mechanical strength, cost savings, and clinical outcomes, is needed to further evaluate this method of closure. In addition, biomechanical analysis of the technique would aid in its evaluation. Future studies are needed to analyze these factors to verify the benefits and viability of the Flint Lock technique.