Complications Associated with Extracapsular Stabilization Using Monofilament Material

Complications Associated with Extracapsular Stabilization Using Monofilament Material

R. Randy Basinger

7.1 Introduction

The definition of lateral extracapsular suture (LES) for the purposes of this chapter will be an extracapsular suture of nylon leader line (NLL) coursing from the lateral surface of the femur to the proximal cranial tibia. The suture is anchored proximally by encircling the lateral fabella or to a bone anchor in the caudolateral femoral condyle distal to the lateral fabella. It is anchored distally to bone tunnel(s) or a bone anchor in the proximal cranial tibia.

7.2 History of Lateral Extracapsular Suture

The LES is a common technique for repair of the cranial cruciate ligament (CCL)‐deficient stifle that was developed in the 1970s [1, 2] and has been performed on tens of thousands of patients over the years. It is probably still the most common surgical procedure performed for treatment of this condition given that general practitioners as well as specialists perform the procedure. Over time, innovations have been made to the original procedure to make it technically easier and more reproducible. Different suture types and means to attach the suture to the femur and tibia, and methods to tension and secure the suture have been introduced [36].

Over the last 30 years, multiple studies have been published about outcomes, complications, comparison of different suture types, fastening methods, anchor types, isometric placement points, and comparison of outcomes to other techniques. No single surgical technique has consistently proven superior. In a number of studies, LES compares favorably to other current techniques [7, 8] and only recently was tibial plateau leveling osteotomy (TPLO) shown to be superior to LES in a controlled study [9].

When the American College of Veterinary Surgeon Diplomates and general practice veterinarians were surveyed in 1999, the majority of dogs under 9.1 kg were still treated by LES [10]. In the same study, LES was still commonly performed in large dogs although more osteotomy procedures were done compared to small dogs. Despite all the options available for CCL disease repair today, LES is still a commonly performed repair technique. This is especially true with general practice veterinarians due to the relative simplicity of the procedure, the low cost of instrumentation and implants to perform the procedure, and the decreased cost to the client compared to osteotomy techniques. Because of the antirotational effect of LES, it is also a useful procedure when there is a coexistent medial patellar luxation (MPL), with or without CCL disease, or when excessive internal rotation is still present after an osteotomy procedure. Finally, the monofilament nature of NLL makes infection risk lower than multifilament suture types due to lower bacterial adherence compared to multifilament sutures [11, 12].

Lateral extracapsular suture is likely to remain a viable surgical treatment option, especially for general practice veterinarians, smaller dogs, and when excessive internal rotation of the tibia or MPL exists.

This chapter will cover patient selection considerations for LES along with preoperative planning tips to minimize complications. In addition, intraoperative technical considerations, complications, identification, and revision strategies will be discussed as well as identification and management of postoperative complications. Tips to avoid intraoperative and postoperative complications will be presented.

7.3 Patient Selection Considerations for Lateral Extracapsular Suture

Historically, LES was performed on all types of veterinary patients largely due to a lack of other treatment options. While many patients did very well, others did not, and critical evaluation over the last 50 years began to shed some light on factors that influenced the outcome of the procedure. Refinements in surgical technique, implants, and equipment occurred which helped with some of the technical and implant complications covered later, but some patients consistently did not due as well as others. How one defines “complication” of a specific procedure also determines whether some outcomes are complications or not.

When multiple procedures exist for the same condition, this author feels it may be fair to consider it a complication if the selected procedure does not consistently meet the expected level of return to function of the other procedures that treat the same condition. Multiple studies compared outcome difference between LES and TPLO or other surgery techniques, with variable conclusions but generally showing LES to be an effective treatment for CCL disease, often showing it to have outcomes no different from or better than other procedures currently in use [1319]. It is important that the client be aware of the expected outcome for a given procedure compared to other options based on clinical studies, and our own subjective assessment of the other variables of the patient’s and owner’s situation and expectations that influence outcome but are not included in published studies.

This author’s approach is generally to recommend TPLO for almost all dogs if finances permit, based on its more consistent ability to return dogs closer to normal function and minimize subsequent osteoarthritis (OA) development [13] compared to LES. However, I do emphasize that LES is certainly a very good procedure and likely to improve comfort and function in patients for clients unwilling to pursue osteotomy procedures. If the patient is small or has concurrent MPL or excessive internal rotation, LES is more frequently recommended. I would not generally recommend bilateral simultaneous LES repair in dogs with bilateral CCL disease due to slower return to weight bearing and concerns of stabilization failure.

It is generally accepted that body weight is a major factor determining expected level of function of dogs with LES, with those weighing more than about 25–30 kg being more likely to have TPLO over LES [10]. Body weight is also a factor in the likelihood of developing complications. In a study of 305 dogs, those heavier than 33.7 kg were more likely to develop complications with LES, defined as an undesirable outcome associated with the surgical procedure or occurring after the surgery that was confirmed via physical examination of the dog at the hospital [20].

In this same study, younger dogs were also reported to be more likely to develop complications. It was theorized that their greater activity level or difficulty in postoperative restraint could be the cause of their increased risk of complications. Overall, 17.4% of patients developed a complication in this study, and 7.2% required an additional surgery [20]. Other studies have reported overall complication rates between 9% and 25% [6].

The progression of OA is greater with LES than TPLO [13]. Due to our current lack of good salvage procedures for end‐stage stifle OA, managing CCL disease to minimize OA development is critical. This includes proper timing of surgical treatment before OA is established, maintaining meniscal integrity, choosing procedures for CCL disease repair most likely to minimize OA development, and being conscientious about follow‐up and weight management.

Dogs with high tibial plateau angles (TPAs) seem more likely to develop problems with repair breakdown, despite one study showing no difference [21]. Measurement of TPA should be part of the minimum database before a specific procedure for CCL disease repair is recommended. More on measuring the TPA can be found in Chapter 10. Many surgeons have performed LES on a small dog who we felt should have done well with a lateral suture repair only to have the suture(s) break in the first 2 weeks postoperatively (PO). When evaluation of TPA became commonplace and we looked at these patients, we found many of them had excessive TPA angles (>34°) and were likely to overpower any LES repair (Figure 7.1).

Postoperative physical rehabilitation has been shown to improve outcomes for patients with CCL disease repaired with LES [22]. In a survey with 376 respondents, 71% of veterinarians recommended postoperative rehabilitation and were more than twice as likely to recommend rehabilitation for LES than osteotomy techniques [23]. The client must be aware of this, and if postoperative rehabilitation cannot be done for some reason, it may affect the LES outcome and prompt consideration of another treatment. While a full rehabilitation protocol is beyond the scope of this book, additional information on rehabilitation can be found in Chapter 15.

7.4 Preoperative Planning Tips to Minimize Complications

  • Obtain a thorough history of the patients’ current lifestyle and expectations for lifestyle after surgery.
  • In young dogs, consider the increased risk of complications with LES and higher risk of OA development long term given the expected length of life after surgery.
  • In large dogs, recommend an osteotomy technique over LES as likely to give the best outcome.
  • Evaluate the TPA and consider a repair technique other than LES if the TPA is high (>26°) or excessive (>34°) (Figure 7.1a).
  • Determine the pet owner’s ability to undertake formal rehabilitation postoperatively for their pet.

7.5 Intraoperative Technical Considerations, Complications, and Revision Strategies

Lateral extracapsular suture repair techniques have been described previously [1, 2,68]. One modification that the author finds very useful is to avoid the morbidity of a full lateral arthrotomy and instead perform two limited approaches to separately accomplish the two goals of the procedure.

The skin incision for the procedure can be either medial or lateral. A medial “mini‐arthrotomy” is done to evaluate, probe, and excise any damaged meniscal tissue and release the medial meniscus if desired. This incision is closed with several interrupted sutures and the skin incision is reflected laterally. Alternatively, this step can be done via arthroscopy.

For placement of the LES, the caudolateral femoral condyle and fabella are approached by a linear incision directed from the proximal cranial tibia directly toward the fabella, exposing the path that the LES will take and avoiding excessive dissection and a large arthrotomy. If needed, the incision can be carried caudoproximal past the fabella to gain good exposure, though the surgeon will have to split some of the fibers of the biceps muscle at its insertion on the lateral fascia of the joint. This approach provides greater exposure for atraumatic circumfabellar suture placement or easy access to the F2 isometric point on the femoral condyle for bone anchor placement. Good exposure and accurate needle passage around the fabella can also minimize the chance of iatrogenic peroneal nerve damage, which has been reported as a possible complication to LES [20].

Photos depict (a) preoperative lateral radiograph of a 4.3 kg Yorkie with TPA = 36°. (b) Postoperative caudal cranial radiograph documenting bone anchor placement. (c) Two-week postoperative, acutely lame – 2 × 9 kg NLL breakage at knot. (d) Postoperative lateral view of revision with TPLO. Start(e) EndPostoperative caudal-cranial view of revision with TPLO.

Figure 7.1 (a) Preoperative lateral radiograph of a 4.3 kg Yorkie with TPA = 36°. (b) Postoperative caudal cranial radiograph documenting bone anchor placement. (c) Two‐week postoperative, acutely lame – 2 × 9 kg NLL breakage at knot. (d) Postoperative lateral view of revision with TPLO. (e) Postoperative caudal‐cranial view of revision with TPLO.

Regardless of the surgical technique used, the goal of the procedure is to evaluate and treat any meniscal injuries, and then place the LES so that it will minimize cranial translation of the tibia in relation to the femur while periarticular fibrosis imparts long‐term stability to the joint.

Diagnosis and management of meniscal injuries is covered in Chapter 18. A significant complication of any CCL disease repair surgery would be to miss a meniscal injury requiring treatment. More specific to LES repair with NLL than other techniques is deciding whether or not to release the medial meniscus. Given that NLL will stretch, and most repairs will have some cranial tibial subluxation return over time, the risk of subsequent or postliminary meniscal tears is probably higher with this technique. The meniscal release procedure was advised to decrease the risk of postliminary meniscal injury. It is effective in decreasing the risk of subsequent meniscal tears with TPLO [24] and LES [20]. However, the released medial meniscus is less able to limit cranial tibial subluxation which further challenges the LES repair. Releasing the medial meniscus also concentrates femorotibial contact stress in the caudal portion of the medial compartment, resulting in decreased contact area and increased peak pressure, predisposing to OA development [25].

While there is considerable controversy regarding medial meniscal release, it is fair to say that there is further stress on the LES repair and an increased risk of OA development when meniscal release is performed, and an increased risk of postliminary meniscal tears when the meniscus is not released. An older dog or one in which the possibility of a second surgery to treat a postliminary meniscal tear is not an option might be the most reasonable patient for which to consider meniscal release in conjunction with LES.

After the fabella and proximal tibia have been exposed for placement of the LES, the surgeon must decide whether the fabella or a bone anchor will be used as the proximal anchor point. When the fabella is chosen as the proximal LES attachment point, care must be taken to avoid disruption of the attachment of the fabella to the caudal aspect of the femur. This is especially true in small patients for which LES is commonly chosen. In a study of dogs <7 kg, the mean lateral fabellar diameter was only 2.9 mm, and one dog had an absence of a lateral fabella [26]. Occasionally, bipartite fabella are noted as well. In an effort to minimize the chance of LES failure due to disruption of the attachments of the fabella to the femur, this author uses a bone anchor (Figure 7.1

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Apr 3, 2022 | Posted by in EQUINE MEDICINE | Comments Off on Complications Associated with Extracapsular Stabilization Using Monofilament Material
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