The prevalence of symptomatic osteoarthritis of the thumb carpometacarpal (CMC) joint is estimated to be 1.9%,1 affecting about 6 million people in the United States. Many of these individuals elect to undergo surgery to alleviate pain and restore function of the thumb. Several treatment options have been described, including trapeziectomy alone and trapeziectomy with ligament reconstruction tendon interposition (LRTI). One of the most common surgical techniques involves trapeziectomy with LRTI using the flexor carpi radialis (FCR) tendon as a graft.2 When performing this procedure, the surgeon may elect to harvest the entire FCR or only half of the tendon based on surgeon preference. Both methods are commonly used and they yield similar clinical outcomes.3–5 In theory, the advantage of using a split FCR tendon is that the patient is left with half of the native tendon to assist in wrist flexion and radial deviation. Although this maintenance of clinical strength and function has not been proven in vivo, it seems appealing to leave the patient with part of the tendon, especially if it would not fit through the metacarpal bone tunnel and would be discarded anyway. In contrast, the theoretical advantage of using the whole FCR tendon is to avoid the potential complication discussed in this paper.
We present our experience of 200 consecutive thumb CMC arthroplasties which demonstrates an under-discussed complication associated with harvesting half of the FCR tendon for LRTI. In the postoperative period, some patients complain of pain over the remaining half of the FCR tendon in the forearm to wrist area. The vast majority of the time this pain is inconsequential and goes away as quickly as it came without any treatment. However, there are a few patients whose pain may persist and end up requiring a reoperation for FCR tendon excision. Several studies have made brief mention of this complication6,7 but only while presenting comparative data of various arthroplasty techniques. The goal of this paper is to describe the presentation and treatment of this complication. We also discuss the potential etiology of persistent FCR pain after LRTI, and we provide suggestions for avoiding this potential complication at the time of the initial surgery.
We retrospectively reviewed a consecutive series of 200 thumb CMC arthroplasties with half FCR LRTI between 2006 and 2014, all of which were casted for 1 month postoperatively in a thumb spica fiberglass cast with the interphalangeal joint free before going to hand therapy. There were 4 patients in this series who, despite reporting improvement of arthritic pain after the surgery, developed enough postoperative pain in the wrist and forearm area overlying the remaining FCR tendon to eventually warrant FCR excision. Three out of the 4 patients reported feeling a snap in their forearm during the postoperative period within the first month while they were casted. This caused a great deal of pain initially in the volar forearm and eventually subsided to a chronic, less intense level of pain. There was focal tenderness at the distal aspect of the FCR area just proximal to the wrist crease in these 3 patients. The other patient who did not feel a snap complained of a similar chronic forearm pain in this region as well as proximally over the remaining FCR tendon. After a trial of conservative treatment which included physiotherapy, manual massage, iontophoresis, and anti-inflammatory medication (both orally and topically), each patient eventually underwent a reoperation at a mean of 5 months to remove the remaining half of the FCR tendon. This was done in the 3 patients who only had pain distally by opening up the proximal aspect of the CMC incision over the area of maximal tenderness and excising the FCR remnant. In the other patient who was tender distally and proximally, we opened both the proximal aspect of the CMC incision as well as the proximal forearm incision, and the entirety of the FCR tendon/scar was excised using these 2 surgical windows. All 4 patients reported an improvement in their FCR-related pain postoperatively. The FCR revision procedure of course did not compromise the LRTI previously performed.
As mentioned previously, the technique we typically use involves a split half FCR tendon. After removing the trapezium and creating a bone tunnel through the first metacarpal base, one half of the FCR is harvested. An incision is made in the forearm at the myotendinous junction of the FCR (Fig. 1A). Care is taken to preserve the tendon sheath while entering the sheath to loosen it from its tendinous attachments (Fig. 1B). Next a small longitudinal incision is made in the distal aspect of the tendon (Fig. 1B) proximal to where the tendon travels deep to the trapezium. To split the tendon longitudinally from distal to proximal, we use a #2 FiberWire suture which is passed deep to the preserved tendon sheath and brought out through the proximal incision (Fig. 1A). One half of the FCR tendon is then cut transversely and the graft is brought out of the distal incision and threaded through the intramedullary metacarpal bone tunnel, out of the dorsal bone tunnel, and tied to itself to suspend the metacarpal base. The remaining end of the tendon is stitched into an anchovy-like structure to fill the space of the excised trapezium.
Currently there is no consensus regarding the incidence of post-LRTI FCR pain and subsequent reoperation. Our retrospective analysis of 200 consecutive split FCR LRTIs revealed 4 cases of postoperative FCR area pain that were symptomatic enough to require an eventual FCR tenotomy. In a Cochrane Review, Wajon et al7 reported 4 randomized or quasi-randomized controlled trials that together identified 10 postoperative FCR ruptures of 137 trapeziectomy+LRTI procedures. Similarly, Naram et al6 reported that of 103 thumb CMC arthroplasties using LRTI, there was 1 case of postoperative FCR tendonitis that required FCR tenotomy. It should be noted that the authors pooled adverse events data for split and full FCR graft techniques, so the reported incidence of FCR tendonitis/rupture in the literature may be artificially low. To our knowledge, there was no discussion of the etiology or prevention of this complication.
Burton and Pellegrini3 were the first to describe FCR LRTI arthroplasty as a treatment for thumb CMC osteoarthritis. Using a split FCR graft, they reported excellent results in 92% of cases (23 thumbs) with improved functional outcomes compared with silicone implant arthroplasty.3 Follow-up at 8 to 11 years showed that 95% of patients had excellent relief of pain and increased grip strength and tip pinch strength.5 Patients experienced only modest subluxation of the metacarpal base and very little loss of arthroplasty space height.5
Since 1986, various modifications of Burton and Pellegrini’s arthroplasty technique have been developed including the use of a full FCR graft, and other graft sources such as the abductor pollicis longus tendon.2 In regards to split and full FCR grafts, both techniques are commonly used since they each lead to excellent improvement of thumb CMC osteoarthritis.3–5 The decision about which technique to use is a matter of surgeon preference.
In all 4 cases which were brought back for later FCR excision, we found significant FCR hypertrophy and subcutaneous scarring of the tendon. Based upon our intraoperative findings, persistent forearm pain after LRTI in our series was likely the result of at least a partial FCR tendon rupture and resultant scarring underneath the forearm skin. A typical intraoperative finding at the time of the second surgery was a thickened, hypertrophic FCR tendon (Fig. 2).
To minimize the risk of a subsequent rupture of the remaining half of the FCR tendon, the surgeon should try to split the FCR tendon longitudinally exactly in the middle (Fig. 1A). Furthermore, when harvesting the FCR tendon, care should be taken to preserve the tendon sheath as much as possible. Retaining the sheath may be advantageous for preventing FCR prominence in the forearm and minimizing the likelihood of subcutaneous scarring/adherence of the tendon to the skin.
Surgeons who harvest split FCR grafts for the LRTI procedure may consider harvesting the full FCR tendon in specific circumstances. If the distal FCR tendon looks particularly thin, of poor quality, or tenosynovitic, the surgeon may opt to harvest the entire FCR tendon during the initial procedure. Selective use of the full FCR graft is an appropriate alternative to split grafts since many surgeons harvest the full FCR tendon as their standard procedure without any clinical detriment. Full grafts have been shown to produce favorable DASH, grip, and pinch scores4,8 and no long-term functional deficits.8–10 Therefore they are a fine alternative for the surgeon who usually uses split grafts, and may be indicated to avoid the potential complication discussed in this paper.
More research is needed to elucidate the true incidence and etiology of this under-discussed complication. In the meantime surgeons using split FCR grafts for LRTI can consider these recommendations to potentially decrease the rate of reoperation for FCR-related complications after thumb CMC arthroplasty LRTI surgery.
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