Fig. 14.1
Detritic synovitis from a silicone implant
Fig. 14.2
Erosion of the plantar aspect of the proximal phalanx (red arrow)
Metallic implants may still present with a similar detritic reaction, but more often peri-implant lysis and secondary loosening of the implant. Subsidence of the implant can occur in hemi- and total implants. This will often have significant bony destruction. Even in the case of a hemi-arthroplasty , bone loss can be significant enough that revision requires the use of a structural bone graft to restore normal metatarsal weight-bearing parabola [5, 12, 13] (Figs. 14.3 and 14.4).
Fig. 14.3
Loosening and subsidence of a hemi-implant
Fig. 14.4
Loosening of the implant in the head of the metatarsal and subsidence of the implant into the base of the proximal phalanx
As with any arthroplasty, the dreaded complication is infection. The literature specifically on the incidence of infection with first MTPJ arthroplasty is scant, but the percentages in the available case reports suggest it is quite low [14]. Furthermore, there is no evidence-based algorithmic approach to addressing infection, and protocols have been extrapolated from the hip and knee literature.
Workup
A thorough history will often guide the surgeon as to why the implant may have failed. Most patients will present with pain. This may be in the first MTPJ or elsewhere, for example, with sub-second metatarsal pain. A thorough understanding of the subjective issues must be complimented with an appreciation of the patient’s expectations.
Signs and symptoms of infection (local and systemic) should be noted and addressed appropriately. History of a draining sinus tract over the joint is ominous and should heighten concerns that an infection, either fulminant or occult, is present.
Clinical Evaluation
The first step is to evaluate for signs of infection. The cardinal signs of inflammation may represent infection but may also be due simply to implant loosening or reactive synovitis or inflammation from the implant material. Any evidence of an open wound or draining sinus tract should be fully inspected and in and of itself is an indication for surgical exploration [15].
Once the likelihood of infection has been addressed, the next step is to assess for contributing proximal pathology. Ankle equinus and clinically significant hindfoot or midfoot deformity or instability may both contribute to the implant’s failure. These should be fully evaluated and addressed at the time of revision [16].
Deformity and functional derangement of the first ray must be evaluated. First ray hypermobility should be taken into consideration and addressed. Deformity in the first MTPJ may present as hallux valgus and/or hallux malleus. Flexibility of these deformities will determine the optimal procedure(s).
Lesser MTPJ pain may be the chief complaint. Evaluation for MTPJ instability (plantar plate and/or collateral ligaments) and the existence of digital deformities should be considered and addressed appropriately.
Imaging
Weight-bearing plain films are evaluated for the presence of peri-implant lucency (Fig. 14.4). This likely suggests instability but should also be considered as a sign of infection if coupled with other clinical evidence. An inventory of bone loss and disturbance of the weight-bearing parabola is taken and severity determined. This is an essential component of the evaluation as this will have a profound impact on the reconstructive plan. With defects of >1 cm, serious consideration should be given for a staged reconstruction. Acute correction of defects of this size or larger may result in vascular and/or neural injury.
In the case of hallux valgus , standard radiographic evaluation is undertaken noting severity and apex of deformity. As first MTPJ arthrodesis is the most common salvage procedure, one can anticipate between 5 and 8° of IM correction [17]. The hallux interphalangeal joint (HIPJ) is evaluated for deformity in all three planes as well as for arthritis.
Laboratory Data
If an infection is suspected, an aspiration of the joint is recommended. The presence of purulence is not diagnostic of infection. In the case of metal on metal (MoM) implants, it may be indicative of a foreign body reaction. Fluid is evaluated for cultures (aerobic, anaerobic, fungal, AFB) and sensitivities. WBC and differential is evaluated as well. A synovial WBC >3000/mL and polymorphonuclear cells (PMNs) >80% have the highest accuracy and sensitivity for infection [18].
Evaluation of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are also in order. ESR of >30 mm/h and CRP > 10 mg/dL are highly suggestive of infection. Taken together, the sensitivity for infection is estimated to be 93% and warrants further investigation [15]. In this instance, surgery is usually indicated to get synovial culture and biopsy. A negative culture doesn’t rule out infection. In addition, an elevated synovial CRP has been reported to have an accuracy of 91% [15]. In addition to a positive culture, this can be the impetus to start an infected implant treatment protocol.
Procedures
There are four options for treatment for failed implants of the first metatarsal phalangeal joint: maintain the implant, removal of the implant and reimplantation at a later date, removal of implant, or arthrodesis. The decision of which option to choose will be determined by the diagnosis, quality of the soft tissues and bone, and whether there is an infection. An arthrodesis is the most definitive of these procedures but can be a challenging surgery. Hecht et al. [19] showed that arthrodesis of a failed silicone implant improved patient’s average walking tolerance, ability to wear shoes, and overall level of satisfaction. Garras et al. [5] followed 18 patients that were converted from a failed hemi-arthroplasty to a fusion. They showed that the VAS pain score went from 0.75 to 7.8 out of 10.
The surgeon should attain adequate intraoperative range of motion during implant surgery of the first metatarsal phalangeal joint. It is essential to make sure that enough bone has been removed, the implant is well placed, and the sesamoids are gliding. There are times when the postoperative motion is significantly reduced even when good surgical technique has been followed. Patients should be educated on range of motion exercises preoperatively and instructed to do range of motion exercises in the immediate postoperative period to prevent arthrofibrosis and limitation of joint range of motion. Conservative measures should be attempted as soon as loss of motion becomes evident. Physical therapy for range of motion exercises combined with ultrasound may be used in conjunction with cortisone injections. When cortisone injections are used, injectables that do not contain crystals are recommended; crystals can be destructive to the implant. When there is no improvement in the range of motion or continued loss of motion, closed manipulation of the joint under anesthesia can be attempted. Doing a local block and attempting this in the office are not advised as this can be painful and the patient will guard preventing the motion from being attained. An open arthrotomy with debridement of the fibrosis can be used, but the authors have not found this to be very successful. There are times when inadequate bone resection is preventing motion (Fig. 14.5).
Fig. 14.5
Arrows demonstrating inadequate bone resection, preventing range of motion
These cases will require revision surgery with adequate debridement to allow for improved range of motion. If there is continued loss of motion, but no pain, the patient may opt to live with the implant and limited range of motion. For those patients that have pain along with the loss of motion, arthrodesis is usually the best option. Patients that have had a hemi-implant can be converted to a total implant. The authors have found that there is often a significant loss of joint space in failed hemi-implants (Figs. 14.6 and 14.7). This may prevent successful conversion to a total implant and necessitate an arthrodesis.
