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Long-term follow-up of silastic joint replacement of the first metatarsophalangeal joint
The Foot 13 (2003) 151–155
Long-term follow-up of silastic joint replacement of the first metatarsophalangeal joint夽 R. Bommireddy, S.K. Singh∗ , P. Sharma, M. El Kadafi, D. Rajan, M. Rowntree Queen Mary’s Hospital, Sidup, Kent, UK Received 28 September 2002; received in revised form 7 April 2003; accepted 28 April 2003
Abstract Aim: To assess long-term outcome of silastic joint replacement of the first metatarsophalangeal joint. Methods: Thirty-two patients (42 feet) with double-stem silicone implant arthroplasty of the first metatarsophalangeal joint were reviewed at an average of 8 years (range 4–19 years). Surgery was for hallux rigidus in 25 cases and for hallux valgus with degenerative osteoarthritis in 17 cases. Patients with rheumatoid arthritis were excluded. Mean patient age was 64 years. Results: Twenty-eight of the 32 patients were very satisfied with the procedure. No patients were dissatisfied. Pain relief was subjectively excellent or good in 28 patients. Three of the four patients with fair or poor relief of pain had surgery for hallux valgus with degenerative osteoarthritis. Radiographs showed sclerosis around all prostheses having cysts with bony erosions in 17 cases. Twelve had clinical features of silicone synovitis in the early postoperative period but this was not present at final review despite radiological findings of new bone formation (57%) and localised osteolysis (40%). Two patients had transfer metatarsalgia with a stress fracture. No patient required revision surgery. Conclusion: Our long-term study shows patients to have very good subjective and objective results despite poor radiological results. There is a role for double-stemmed silicone implant arthroplasty in low demand patients. © 2003 Elsevier Ltd. All rights reserved. Keywords: Metatarsophalangeal joint; Silastic; Arthroplasty; Hallux valgus; Hallux rigidus
1. Introduction Few foot operations raise as much controversy as surgery on the first metatarsophalangeal joint for degenerative change. Options include cheilectomy, resection arthroplasty, arthrodesis and prosthetic replacement [1–3]. The results of the Keller’s arthroplasty are unsatisfactory [4]. Arthrodesis produces good results [5] but requires rigid internal fixation, can increase stress in other joints and the rigid 1st ray limits shoe wear. Many authors [6,7] have demonstrated cheilectomy to be effective in treating mild to moderate osteoarthritis of the first metatarsophalangeal joint. It is not indicated in severe osteoarthritis. The treatment of choice for moderate to severe hallux valgus is first metatarsal osteotomy [8]. In the presence
夽 Work undertaken at the Queen Mary’s Hospital, Sidcup, Kent, UK. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. ∗ Corresponding author. Tel.: +44-7989-608787; fax: +44-207-231-6140. E-mail address: [email protected] (S.K. Singh).
0958-2592/$ – see front matter © 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0958-2592(03)00041-5
of pre-existing degenerative changes in the metatarsophalangeal joints they give poor symptomatic relief. Early results of silastic joint replacement of the first metatarsophalangeal joint were encouraging [9]. Patients reported a reduction in pain, were functionally good and often had no restriction in footwear. A growing number of reports now suggest that silastic joints may be unsuitable for weight-bearing applications in the body [10]. Whilst the implants themselves do not cause a reaction, they generate wear debris that can lead to synovial reaction [11]. This debris has been localised in distal lymph nodes [12]. The aim of our study was to determine the long-term clinical and radiological outcomes of the flexible hinged silicone arthroplasty of the first metatarsophalangeal joint.
2. Patients and methods Between 1981 and 1996 we performed 57 silastic arthroplasties of the first metatarsophalangeal joint in 44 patients. Four patients who had this operation for rheumatoid arthritis
152
R. Bommireddy et al. / The Foot 13 (2003) 151–155
Table 1 Patient satisfaction with surgery, pain relief and clinical grading of the 42 feet (32 patients) Clinical features Patient satisfaction [13] Completely satisfied Somewhat satisfied Dissatisfied
Definition
Number of patients
Would have same operation on other side
24 4 4
Pain relief Excellent Good Fair Poor
Mild pain on intermittent basis Better than preoperative pain No improvement
14 14 2 2
Clinical grading [14] Excellent Good Fair Poor
Complete axial alignment Valgus <15 , slight pronation Valgus 15–30 /better than preoperative deformity Valgus deformity >30 ; any revision surgery
17 19 4 2
Table 2 Features observed on the radiographs of the 42 feet (32 patients) Radiological features
Definition
New bone formation [13] None Slight Moderate Severe Complete osseous bridging
New bone production at the cut end of metatarsal or proximal phalanx
Radiolucencies None Slight Moderate Severe
Number of cases
Small but detectable formation of spurs only Less than 50% encroachment on joint space 50% or more encroachment
18 11 9 4 0
<2 mm 2–4 mm >4 mm
0 10 6 1
Integrity of implant [10] No deformation or implant fracture Slight deformation or implant fracture Complete destruction of implant
were excluded from this study. Three patients had died and five were lost to follow-up. An independent observer (RB) reviewed 42 feet in 32 patients (30 female, 2 male) with a mean age of 64 years at follow-up in a research clinic. Patients were assessed for pain relief, alignment, length of the hallux, transfer metatarsalgia and other gait disorders. Weight-bearing anteroposterior and lateral radiographs of the foot were taken. Twenty-five operations were done for degenerative osteoarthritis of the first metatarsophalangeal joint and 17 for osteoarthritis of the first metatarsophalangeal joint in a hallux valgus foot. Those included in the study failed to respond to a protocol of conservative treatment, including advice on footwear and steroid injections. Low demand patients were considered for arthroplasty even if they had previous surgery as long as there was adequate bone stock. Patients with a high functional demand or local infection were not considered for silastic arthroplasty. We used double-stemmed sil-
41 1 0
icone prostheses without a titanium shield grommet, which were all inserted by the original technique as described by Swanson [13]. Patient satisfaction with surgery, pain relief and clinical outcome was assessed and graded as shown in Table 1. The radiological assessment is summarised in Table 2.
3. Results Thirty-two patients (42 feet) were available for this study that had double-stem silicone implant arthroplasty of the first metatarsophalangeal joint between 1981 and 1996. Duration of follow-up ranged from 4 to 19 years, the mean being 8 years. Of the four dissatisfied patients shown in Table 1, three were in the hallux valgus group and one in the hallux rigidus group. The average age of these four patients at 60 years was less than the mean age of 64 years for the group. This
R. Bommireddy et al. / The Foot 13 (2003) 151–155
difference was not statistically significant. Five patients had previous surgery to their great toe—four a Keller’s arthroplasty and one a bunionectomy. Four had good pain relief and cosmetic results after silastic arthroplasty. One had poor pain relief but a good cosmetic result. In 8 feet the great toe was shorter than the other side— being more than 0.5 cm in two cases. One great toe was held in pronation and three had 5–10◦ of extension deformity. Two patients with a poor cosmetic result had a severe hallux valgus deformity before surgery (metatarsophalangeal angles 32 and 34◦ ) but excellent pain relief in our long-term study. All patients, except for one with poor pain relief, had a normal gait. Nine patients (21%) still wore wide fitting shoes but were pain free. Four patients initially reported symptoms of metatarsalgia that resolved by their first postoperative year. Range of motion at the first metatarsophalangeal joint varied from 10 to 25◦ of dorsiflexion and 10 to 20◦ of plantar flexion. Twelve implants in nine patients (28% of feet) had early postoperative inflammation or wound healing problems with no organisms being isolated. Their swelling took up to 1 year to resolve. At final follow-up there was no clinical evidence of synovitis and eight of these nine patients reported excellent or good pain relief and patient satisfaction.
153
Fig. 2. Standing radiograph of a 44-year-old female at 9-year followup. The metatarsal stem of the implant has fractured and note the degree of proximal phalanx osteolysis. The patient however reports good subjective results.
3.1. Radiographic results The results of bone production, radiolucencies and integrity of the implant are shown in Table 2. Sclerotic lines were observed around all 42 prostheses— in 4 it was only around the proximal stem and in 3 only around the distal stem (Fig. 1). Thirty-four feet had joint space preserved at a width of 4–6 mm. Eight had a joint width of 2–3 mm suggesting sinkage of the prosthesis. In one patient who had a previous Keller’s arthroplasty, the prosthesis migrated across the IP joint and was seated in the distal phalanx. The toe was severely shortened with gross restriction in joint motion. At 11-year follow-up, one patient was noted to have a prosthetic fracture at the hinge causing the proximal phalanx to sublux (Fig. 2). One patient sustained a stress fracture of the second metatarsal 2 years after surgery but at 3 years had no new radiological complications and the metatarsalgia had settled.
4. Discussion
Fig. 1. Standing radiograph of a 59-year-old female taken at 7-year follow-up. Note the hallux valgus deformity and the marked proximal phalanx osteolysis. The patient had an excellent subjective result.
The aim of surgery for first metatarsophalangeal joint arthritis is to relieve pain and restore function. The pathology is degenerative change, which may be isolated or associated with hallux valgus. It is important to select an appropriate operation for reconstruction of the forefoot. Length and alignment of the great toe should be maintained to avoid transfer lesions or a cosmetically unacceptable toe.
154
R. Bommireddy et al. / The Foot 13 (2003) 151–155
Early reports by Swanson [13] on first metatarsophalangeal joint athroplasty using a flexible hinged prosthesis were promising. In vitro and animal studies demonstrated hinged silicone prostheses to be durable and biocompatible. Cracchiolo et al. [14] reported on the average 5.8-year follow-up of 34 similar feet. Shankar et al. [15] on 2-year follow-up of 89 patients found 90% to have excellent or satisfactory subjective and objective results. Cracchiolo et al. [16] in a two-centre study reported on the average 3-year follow-up of their patients. Laird [17] reported 89% excellent or good results at 4-year retrospective follow-up. Our average follow-up is 8 years. Eighty-seven percent had excellent to good pain relief and 87% of the patients were satisfied with the long-term outcome of their procedure. These results support the findings of Grace et al. [18] who presented 90–95% success rate and 95% implant survival in 45 consecutive patients with 5- to 10-year follow-up. Reduced dorsiflexion of the first metatarsophalangeal joint is characteristic of hallux rigidus. Swanson et al. [19] noted that the dorsiflexion reduced with time after silastic arthroplasty. Shaw and Epstein [20] observed an average 49◦ arc of motion in 47 hallux rigidus patients at 7-year average follow-up [20]. We observed 20–45◦ arc of motion in all cases, a range adequate for normal gait [19]. All long follow-up studies report an increased number of implant failures and complications [11,21,22]. The complications after silastic joint replacement surgery include a soft tissue inflammatory reaction simulating infection, silicone particulate synovitis, osteolysis, prosthetic wear and fragmentation with proximal migration of silicone particles causing inguinal lymphadenopathy [10,11,14,23]. In our group of patients, 28% clinically showed early inflammation suggestive of silicone synovitis that was no longer present at an average 8-year follow-up. Shankar et al. [15] reported similar high numbers of early local inflammation but two of their patients developed a deep infection that necessitated implant removal. Cracchiolo et al. [14] at 5.8 years reported no evidence of clinical or radiological silicone synovitis. The radiographic appearance of the bone spurring may be an inflammatory response to silicone particles. Fifty-seven percent of our patients showed bone production at the first metatarsophalangeal joint and in 10% of cases it was severe. Patients with spurring were noted to have a reduced range of motion. There were no cases of osseous fusion due to severe new bone formation [14]. A sclerotic line surrounded all 42 silicone prosthetic stems—this may be a favourable sign indicating the absence of an undesirable reaction within the bone, which would give a lytic area [14]. There were radiolucencies around 17 stems and in 12 the radiolucent areas were at the distal stem where the implant is smaller and does not fit as snug in the intramedullary canal. Whilst there is no clinical evidence of synovitis, radiolucencies would suggest that the prostheses are not completely inert. Cracchiolo et al. report a similar incidence of osteolysis whilst Rahman and Fagg
[11] noted significant radiolucency in 72% of patients and in all where the prostheses had been implanted longer than 4 years. Shaw and Epstein observed that 39% of prostheses were loose at final follow-up and by their criteria, 61% of implants had failed. The incidence of implant fracture varies from 1% [13] to 8% [23]. One author [10] has abandoned this procedure because of radiographic evidence of fracture of the implant in his patients. Their group is not comparable: the average patient at 55 years of age is younger than our 64 years and the majority of their patients had previous surgery on the same toe. We report our incidence of implant fracture at 3%. Cracchiolo et al. [14] observed that 3 of their 66 patients had implant fractures. As these patients otherwise had good clinical results, the damaged implants were left in situ [14]. Our study shows patients to be more pleased with the result of surgery than one would expect from objective clinical and radiological assessments. We agree that the implant functions mainly as a spacer [10]. It remains intact only long enough for fibrous tissue to form. This fibrous tissue then dictates the biomechanics of the joint, providing pain relief regardless of the condition of the implant. If we use revision as the end point, then our group has 100% survival of the prosthesis at an average of 8 years. These patients will now be followed up annually for implant survival analysis. In conclusion, our study with an average 8-year follow-up suggests that there is a definite role for double-stemmed silicone implant arthroplasty in low demand patients to treat osteoarthritis of the first metatarsophalangeal joint or osteoarthritis associated with hallux valgus. Ninety percent had excellent or good patient satisfaction, pain relief and gait. Whilst radiological evidence of silicone synovitis was noted in the form of radiolucencies in 40% of implants, this did not correlate with the good subjective results.
References [1] Keller WL. Surgical treatment of bunions and hallux valgus. NY Med J 1904;80:741. [2] Mann RA, Coughlin MJ, DuVries HL. Hallux rigidus. A review of the literature and a method of treatment. Clin Orthop 1979;142:57– 63. [3] Gould N. Hallux rigidus: cheilectomy or implant? Foot Ankle 1981;1:315–20. [4] Vallier GT, Peterson DA, La Grone MO. The Keller resection arthroplasty. A 13-year experience. Foot Ankle 1991;11:187–97. [5] McKeever DC. Arthrodesis of the first metatarsophalangeal joint for hallux rigidus and metatarsus primus varus. J Bone Joint Surg Am 1952;34:129. [6] Mann RA, Clanton TO. Hallux rigidus: treatment by cheilectomy. J Bone Joint Surg Am 1988;70:400–6. [7] Singh SK, Bommireddy R, El-Kadafi M, Mani GV. Cheilectomy or silastic joint replacement for hallux rigidus. J Bone Joint Surg Br 2001;83(Suppl III):337. [8] Mann RA. Decision-making in bunion surgery. Instr Course Lect 1990;39:3–13.
R. Bommireddy et al. / The Foot 13 (2003) 151–155 [9] Swanson A, Lumsden R, Swanson G. Silicone implant arthroplasty of the great toe. A review of single stem and flexible hinge implants. Clin Orthop 1979;142:30–42. [10] Granberry W, Noble P, Bishop J. Use of a hinged silicone prosthesis for replacement arthroplasty of the first metatarsophalangeal joint. J Bone Joint Surg Am 1991;73:1453–61. [11] Rahman H, Fagg PS. Silicone granulomatous reaction after first metatarsophalengeal hemiarthroplasty. J Bone Joint Surg Br 1993;75: 637–9. [12] Nalbandian RM. Synovitis and lymphadenopathy in silicone arthroplasty implants. J Bone Joint Surg Am 1983;65:280–1. [13] Swanson AB. Implant arthroplasty for the great toe. Clin Orthop 1972;85:75–81. [14] Cracchiolo A, Weltmer J, Lian G. Arthroplasty of the first metatarsophalengeal joint with double-stem silicone implant. J Bone Joint Surg Am 1992;74:552–63. [15] Shankar NS, Asaad SS, Craxford A. Hinged silastic implants of the great toe. Clin Orthop 1991;272:227–34. [16] Cracchiolo A, Swanson A, Swanson G. The arthritic great toe metatarsophalangeal joint: a review of flexible silicone implant arthroplasty from two medical centres. Clin Orthop 1981;157:64–9.
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[17] Laird L. Silastic joint arthroplasty of the great toe. A review of 228 implants using double stemmed implants. Clin Orthop 1990;255:268– 72. [18] Grace DL, Banks MJK, Sham RR. First metatarsophalangeal double stem silastic arthroplasty—a five to ten year follow-up study. J Bone Joint Surg Br 2000;82(Suppl III):203. [19] Swanson A, Swanson G, Mayhew DE, Khan AN. Flexible hinge results in implant arthroplasty of the great toe. Rheumatology 1987;11:136–52. [20] Shaw NJ, Epstein HP. Replacement arthroplasty of the first metatarsophalangeal joint foe hallux rigidus. J Bone Joint Surg Br 1997; 79(Suppl):434. [21] Sammarco G, James MD. Complications after surgery of the hallux. Clin Orthop 2001;391:59–71. [22] Kampner SL. Use of hinged silicone prosthesis for replacement arthroplasty of the first metatarsophalangeal joint. J Bone Joint Surg Am 1992;74:1273–4. [23] Kampner SL. Long term experience with total joint prosthetic replacement for the arthritic great toe. Bull Hosp Joint Dis Orthop Inst 1987;47:153–75.
Long-term follow-up of silastic joint replacement of the first metatarsophalangeal joint夽 R. Bommireddy, S.K. Singh∗ , P. Sharma, M. El Kadafi, D. Rajan, M. Rowntree Queen Mary’s Hospital, Sidup, Kent, UK Received 28 September 2002; received in revised form 7 April 2003; accepted 28 April 2003
Abstract Aim: To assess long-term outcome of silastic joint replacement of the first metatarsophalangeal joint. Methods: Thirty-two patients (42 feet) with double-stem silicone implant arthroplasty of the first metatarsophalangeal joint were reviewed at an average of 8 years (range 4–19 years). Surgery was for hallux rigidus in 25 cases and for hallux valgus with degenerative osteoarthritis in 17 cases. Patients with rheumatoid arthritis were excluded. Mean patient age was 64 years. Results: Twenty-eight of the 32 patients were very satisfied with the procedure. No patients were dissatisfied. Pain relief was subjectively excellent or good in 28 patients. Three of the four patients with fair or poor relief of pain had surgery for hallux valgus with degenerative osteoarthritis. Radiographs showed sclerosis around all prostheses having cysts with bony erosions in 17 cases. Twelve had clinical features of silicone synovitis in the early postoperative period but this was not present at final review despite radiological findings of new bone formation (57%) and localised osteolysis (40%). Two patients had transfer metatarsalgia with a stress fracture. No patient required revision surgery. Conclusion: Our long-term study shows patients to have very good subjective and objective results despite poor radiological results. There is a role for double-stemmed silicone implant arthroplasty in low demand patients. © 2003 Elsevier Ltd. All rights reserved. Keywords: Metatarsophalangeal joint; Silastic; Arthroplasty; Hallux valgus; Hallux rigidus
1. Introduction Few foot operations raise as much controversy as surgery on the first metatarsophalangeal joint for degenerative change. Options include cheilectomy, resection arthroplasty, arthrodesis and prosthetic replacement [1–3]. The results of the Keller’s arthroplasty are unsatisfactory [4]. Arthrodesis produces good results [5] but requires rigid internal fixation, can increase stress in other joints and the rigid 1st ray limits shoe wear. Many authors [6,7] have demonstrated cheilectomy to be effective in treating mild to moderate osteoarthritis of the first metatarsophalangeal joint. It is not indicated in severe osteoarthritis. The treatment of choice for moderate to severe hallux valgus is first metatarsal osteotomy [8]. In the presence
夽 Work undertaken at the Queen Mary’s Hospital, Sidcup, Kent, UK. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. ∗ Corresponding author. Tel.: +44-7989-608787; fax: +44-207-231-6140. E-mail address: [email protected] (S.K. Singh).
0958-2592/$ – see front matter © 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0958-2592(03)00041-5
of pre-existing degenerative changes in the metatarsophalangeal joints they give poor symptomatic relief. Early results of silastic joint replacement of the first metatarsophalangeal joint were encouraging [9]. Patients reported a reduction in pain, were functionally good and often had no restriction in footwear. A growing number of reports now suggest that silastic joints may be unsuitable for weight-bearing applications in the body [10]. Whilst the implants themselves do not cause a reaction, they generate wear debris that can lead to synovial reaction [11]. This debris has been localised in distal lymph nodes [12]. The aim of our study was to determine the long-term clinical and radiological outcomes of the flexible hinged silicone arthroplasty of the first metatarsophalangeal joint.
2. Patients and methods Between 1981 and 1996 we performed 57 silastic arthroplasties of the first metatarsophalangeal joint in 44 patients. Four patients who had this operation for rheumatoid arthritis
152
R. Bommireddy et al. / The Foot 13 (2003) 151–155
Table 1 Patient satisfaction with surgery, pain relief and clinical grading of the 42 feet (32 patients) Clinical features Patient satisfaction [13] Completely satisfied Somewhat satisfied Dissatisfied
Definition
Number of patients
Would have same operation on other side
24 4 4
Pain relief Excellent Good Fair Poor
Mild pain on intermittent basis Better than preoperative pain No improvement
14 14 2 2
Clinical grading [14] Excellent Good Fair Poor
Complete axial alignment Valgus <15 , slight pronation Valgus 15–30 /better than preoperative deformity Valgus deformity >30 ; any revision surgery
17 19 4 2
Table 2 Features observed on the radiographs of the 42 feet (32 patients) Radiological features
Definition
New bone formation [13] None Slight Moderate Severe Complete osseous bridging
New bone production at the cut end of metatarsal or proximal phalanx
Radiolucencies None Slight Moderate Severe
Number of cases
Small but detectable formation of spurs only Less than 50% encroachment on joint space 50% or more encroachment
18 11 9 4 0
<2 mm 2–4 mm >4 mm
0 10 6 1
Integrity of implant [10] No deformation or implant fracture Slight deformation or implant fracture Complete destruction of implant
were excluded from this study. Three patients had died and five were lost to follow-up. An independent observer (RB) reviewed 42 feet in 32 patients (30 female, 2 male) with a mean age of 64 years at follow-up in a research clinic. Patients were assessed for pain relief, alignment, length of the hallux, transfer metatarsalgia and other gait disorders. Weight-bearing anteroposterior and lateral radiographs of the foot were taken. Twenty-five operations were done for degenerative osteoarthritis of the first metatarsophalangeal joint and 17 for osteoarthritis of the first metatarsophalangeal joint in a hallux valgus foot. Those included in the study failed to respond to a protocol of conservative treatment, including advice on footwear and steroid injections. Low demand patients were considered for arthroplasty even if they had previous surgery as long as there was adequate bone stock. Patients with a high functional demand or local infection were not considered for silastic arthroplasty. We used double-stemmed sil-
41 1 0
icone prostheses without a titanium shield grommet, which were all inserted by the original technique as described by Swanson [13]. Patient satisfaction with surgery, pain relief and clinical outcome was assessed and graded as shown in Table 1. The radiological assessment is summarised in Table 2.
3. Results Thirty-two patients (42 feet) were available for this study that had double-stem silicone implant arthroplasty of the first metatarsophalangeal joint between 1981 and 1996. Duration of follow-up ranged from 4 to 19 years, the mean being 8 years. Of the four dissatisfied patients shown in Table 1, three were in the hallux valgus group and one in the hallux rigidus group. The average age of these four patients at 60 years was less than the mean age of 64 years for the group. This
R. Bommireddy et al. / The Foot 13 (2003) 151–155
difference was not statistically significant. Five patients had previous surgery to their great toe—four a Keller’s arthroplasty and one a bunionectomy. Four had good pain relief and cosmetic results after silastic arthroplasty. One had poor pain relief but a good cosmetic result. In 8 feet the great toe was shorter than the other side— being more than 0.5 cm in two cases. One great toe was held in pronation and three had 5–10◦ of extension deformity. Two patients with a poor cosmetic result had a severe hallux valgus deformity before surgery (metatarsophalangeal angles 32 and 34◦ ) but excellent pain relief in our long-term study. All patients, except for one with poor pain relief, had a normal gait. Nine patients (21%) still wore wide fitting shoes but were pain free. Four patients initially reported symptoms of metatarsalgia that resolved by their first postoperative year. Range of motion at the first metatarsophalangeal joint varied from 10 to 25◦ of dorsiflexion and 10 to 20◦ of plantar flexion. Twelve implants in nine patients (28% of feet) had early postoperative inflammation or wound healing problems with no organisms being isolated. Their swelling took up to 1 year to resolve. At final follow-up there was no clinical evidence of synovitis and eight of these nine patients reported excellent or good pain relief and patient satisfaction.
153
Fig. 2. Standing radiograph of a 44-year-old female at 9-year followup. The metatarsal stem of the implant has fractured and note the degree of proximal phalanx osteolysis. The patient however reports good subjective results.
3.1. Radiographic results The results of bone production, radiolucencies and integrity of the implant are shown in Table 2. Sclerotic lines were observed around all 42 prostheses— in 4 it was only around the proximal stem and in 3 only around the distal stem (Fig. 1). Thirty-four feet had joint space preserved at a width of 4–6 mm. Eight had a joint width of 2–3 mm suggesting sinkage of the prosthesis. In one patient who had a previous Keller’s arthroplasty, the prosthesis migrated across the IP joint and was seated in the distal phalanx. The toe was severely shortened with gross restriction in joint motion. At 11-year follow-up, one patient was noted to have a prosthetic fracture at the hinge causing the proximal phalanx to sublux (Fig. 2). One patient sustained a stress fracture of the second metatarsal 2 years after surgery but at 3 years had no new radiological complications and the metatarsalgia had settled.
4. Discussion
Fig. 1. Standing radiograph of a 59-year-old female taken at 7-year follow-up. Note the hallux valgus deformity and the marked proximal phalanx osteolysis. The patient had an excellent subjective result.
The aim of surgery for first metatarsophalangeal joint arthritis is to relieve pain and restore function. The pathology is degenerative change, which may be isolated or associated with hallux valgus. It is important to select an appropriate operation for reconstruction of the forefoot. Length and alignment of the great toe should be maintained to avoid transfer lesions or a cosmetically unacceptable toe.
154
R. Bommireddy et al. / The Foot 13 (2003) 151–155
Early reports by Swanson [13] on first metatarsophalangeal joint athroplasty using a flexible hinged prosthesis were promising. In vitro and animal studies demonstrated hinged silicone prostheses to be durable and biocompatible. Cracchiolo et al. [14] reported on the average 5.8-year follow-up of 34 similar feet. Shankar et al. [15] on 2-year follow-up of 89 patients found 90% to have excellent or satisfactory subjective and objective results. Cracchiolo et al. [16] in a two-centre study reported on the average 3-year follow-up of their patients. Laird [17] reported 89% excellent or good results at 4-year retrospective follow-up. Our average follow-up is 8 years. Eighty-seven percent had excellent to good pain relief and 87% of the patients were satisfied with the long-term outcome of their procedure. These results support the findings of Grace et al. [18] who presented 90–95% success rate and 95% implant survival in 45 consecutive patients with 5- to 10-year follow-up. Reduced dorsiflexion of the first metatarsophalangeal joint is characteristic of hallux rigidus. Swanson et al. [19] noted that the dorsiflexion reduced with time after silastic arthroplasty. Shaw and Epstein [20] observed an average 49◦ arc of motion in 47 hallux rigidus patients at 7-year average follow-up [20]. We observed 20–45◦ arc of motion in all cases, a range adequate for normal gait [19]. All long follow-up studies report an increased number of implant failures and complications [11,21,22]. The complications after silastic joint replacement surgery include a soft tissue inflammatory reaction simulating infection, silicone particulate synovitis, osteolysis, prosthetic wear and fragmentation with proximal migration of silicone particles causing inguinal lymphadenopathy [10,11,14,23]. In our group of patients, 28% clinically showed early inflammation suggestive of silicone synovitis that was no longer present at an average 8-year follow-up. Shankar et al. [15] reported similar high numbers of early local inflammation but two of their patients developed a deep infection that necessitated implant removal. Cracchiolo et al. [14] at 5.8 years reported no evidence of clinical or radiological silicone synovitis. The radiographic appearance of the bone spurring may be an inflammatory response to silicone particles. Fifty-seven percent of our patients showed bone production at the first metatarsophalangeal joint and in 10% of cases it was severe. Patients with spurring were noted to have a reduced range of motion. There were no cases of osseous fusion due to severe new bone formation [14]. A sclerotic line surrounded all 42 silicone prosthetic stems—this may be a favourable sign indicating the absence of an undesirable reaction within the bone, which would give a lytic area [14]. There were radiolucencies around 17 stems and in 12 the radiolucent areas were at the distal stem where the implant is smaller and does not fit as snug in the intramedullary canal. Whilst there is no clinical evidence of synovitis, radiolucencies would suggest that the prostheses are not completely inert. Cracchiolo et al. report a similar incidence of osteolysis whilst Rahman and Fagg
[11] noted significant radiolucency in 72% of patients and in all where the prostheses had been implanted longer than 4 years. Shaw and Epstein observed that 39% of prostheses were loose at final follow-up and by their criteria, 61% of implants had failed. The incidence of implant fracture varies from 1% [13] to 8% [23]. One author [10] has abandoned this procedure because of radiographic evidence of fracture of the implant in his patients. Their group is not comparable: the average patient at 55 years of age is younger than our 64 years and the majority of their patients had previous surgery on the same toe. We report our incidence of implant fracture at 3%. Cracchiolo et al. [14] observed that 3 of their 66 patients had implant fractures. As these patients otherwise had good clinical results, the damaged implants were left in situ [14]. Our study shows patients to be more pleased with the result of surgery than one would expect from objective clinical and radiological assessments. We agree that the implant functions mainly as a spacer [10]. It remains intact only long enough for fibrous tissue to form. This fibrous tissue then dictates the biomechanics of the joint, providing pain relief regardless of the condition of the implant. If we use revision as the end point, then our group has 100% survival of the prosthesis at an average of 8 years. These patients will now be followed up annually for implant survival analysis. In conclusion, our study with an average 8-year follow-up suggests that there is a definite role for double-stemmed silicone implant arthroplasty in low demand patients to treat osteoarthritis of the first metatarsophalangeal joint or osteoarthritis associated with hallux valgus. Ninety percent had excellent or good patient satisfaction, pain relief and gait. Whilst radiological evidence of silicone synovitis was noted in the form of radiolucencies in 40% of implants, this did not correlate with the good subjective results.
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