Mid-Term Results of Titanium Hemi-Great Toe Implants

INTRODUCTION

Hallux rigidus is the most common forefoot deformity in patients with osteoarthritis of the foot, with an incidence of 2% to 10% of the adult population. ^6,16 The question as to the best treatment solution for patients with symptomatic grade II or III osteoarthritis with painful hallux rigidus remains controversial. ^9,16,24,25 The shortcomings of debridement with cheilectomy, Keller resection arthroplasty, and arthrodesis have become apparent. ^4,16 The failure of the Swanson silastic prosthesis (Wright Medical Technology, Arlington, TN) in young active patients because of rapid wear, breakage, and tissue foreign body reaction prevented its continued use and usually resulted in poor bone stock for revision procedures. ²³ A few of our patients with Swanson silastic implants have functioned normally with little wear or tissue reaction for many years.

Metallic hemi-replacement arthroplasties have been used successfully in other joints with little wear or tissue reaction, ^1,22 and metallic implants have been available for arthroplasties of the great toe for many years. ¹⁷ The senior author (KK) has used the Swanson titanium great toe implant (Wright Medical Technologies, Arlington, TN) in selected patients for the past 9 years. The purpose of this study was to evaluate the complications, functional results, and outcomes of patients treated with the Swanson titanium great toe implant. ⁷

METHODS AND MATERIALS

From February 3, 1995, to July 8, 1998, 12 patients (16 toes) had insertion of a titanium (Swanson) hemi-great toe implant. Two patients (three toes) were lost to mid-term followup, leaving 10 patients (13 toes) for inclusion in this study (Table 1). The followup interval was between 37 to 105 months, with an average followup of 66 months since insertion. No patient had bilateral procedures performed the same time. Three patients returned 6 months, 1 year, and 3 years after their first implant to have the second side done. Ten of 12 patients returned for followup. Preoperatively, all patients had hypertrophic arthritis (three patients with grade II disease and seven patients with grade III disease) (Figure 1). ⁹ The seven men and three women had an average age of 53 (range 42 to 60) years. No patient was diabetic. Two patients were obese (more than 60 lbs overweight), two patients were heavy (20 to 60 lbs overweight), and six patients were of normal weight for their height. No routine exercises or physical therapy were ordered before or after surgery. Seven patients (nine toes) related that their work or leisure activities required considerable standing, walking, or stooping (medium demand). One patient (two toes) was an avid runner (more than 3 miles per day) and a daily tennis player (high demand). Two patients were relatively sedentary (low demand). Four patients had previous procedures on their great toes: one had a bunionectomy with progressive post-operative arthritis, two had debridements and cheilectomies with progressive arthritis and cyst formation, and one had debridement and cheilectomy with progressive osteoarthritis and a third metatarsal stress fracture.

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Table 1:

General patient preoperative parameters

Pt #	Surg #	R/L	Implant	Diagnosis	Age at surgery	Sex	Diabetes mellitus	Habitus	Job	Previous procedure same toe	Complication previous procedure
1	1	L	Titanium	Grade III OA	49	M	No	Normal	Salesman, walking on road & golf	None	N/A
2	2	L	Titanium	Grade III OA	57	M	No	Normal	Teacher retired, runs 3 miles/day & plays tennis daily	None	N/A
3	3	L	Titanium	Grade III OA	60	M	No	Normal	Service manager, on feet a lot, retired	None	N/A
4	4	R	Titanium	Grade II OA	54	M	No	Normal	Standing & walking	R great toe bunionectomy	Progressive arthritis
5	5	R	Titanium	Grade III OA	49	F	No	Normal	Social work case manager, 50% desk work	Debridement & cheilectomy MTP joint	Progressive arthritis and 3rd MT stress fracture
6	6	L	Titanium	Grade III OA	55	F	No	Normal	Kindergarden teacher, standing & stooping	None	N/A
2	7	R	Titanium	Grade III OA	57	M	No	Normal	Teacher, retired, runs 3 miles/day&plays tennis daily	Debridement & cheilectomy MTP joint	Progressive DJD after 9 months
1	8	R	Titanium	Grade III OA	52	M	No	Normal	Salesman, walking on road & golf	None	N/A
7	9	R	Titanium	Grade II OA	44	M	No	Obese	Digital prepress operator, standing	None	N/A
8	10	L	Titanium	Grade III OA	42	M	No	Obese	Security guard, standing & walking	None	N/A
6	11	R	Titanium	Grade III OA	56	F	No	Normal	Kindergarden teacher, standing & stooping	None	N/A
9	12	R	Titanium	Grade II OA	55	M	No	Fat	Computer designer, walks 2–3 miles qod	None	N/A
10	13	R	Titanium	Grade III OA	54	F	No	Fat	Office, sit down	1st MTPJ debridement & cheilectomy	Progressive arthritis w cysts
					Av. Age 53

R = right; L = left; MT = metatarsal; DJD = degenerative joint disease.

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Fig. 1:

Anteroposterior, oblique, and lateral radiographs of patient with Grade III osteoarthritis.

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Fig. 2:

Anteroposterior, oblique, and lateral radiographs of patient with titanium implant in place 6.5 years showing mild lucency and subsidence.

Postoperative Evaluation

Patients were evaluated for postoperative complications, transfer metatarsalgia, need for future procedures, radio-graphic changes, and speed of recovery. The Koenig Scoring and the American Orthopaedic Foot and Ankle Society (AOFAS) Forefoot Clinical Scoring systems were used as part of this evaluation for completeness and comparison. ^13,15 Retrospective preoperative clinical scoring was not done. ²⁸ To quantitate the quality of implant fixation into the proximal phalanx of the great toe, a radiographic grading system was used (Table 2).

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Table 2:

Implant fixation radiographic grading system

Grade O: Well fixed implant including stem and base of the implant.

Grade 1: Absorption of bone around the base of the implant.

Grade 2: Absorption and lucency, around the base and entire stem of the implant.

Grade 3a: Absorption, lucency, and subsidence of the implant with the stem within the intramedullary canal of the proximal phalanx.

Grade 3b: same as Grade 3a plus abutment of the tip of the implant stem against the cortex but with no cortical reaction.

Grade 4a: Abutment plus cortical hypertrophic reaction at the tip of the implant.

Grade 4b: Penetration or erosion of the tip of the stem through the cortex.

Grade 5: Complete disassociation of the implant in relation to the proximal phalanx and/or first metatarsal head.

RESULTS

There were no infections or hospitalizations, and all wounds healed primarily with the sutures removed in 9 to 21 days (Table 3). All the titanium prosthesis had subsided to varying degrees with lucencies around the implant. The rate of subsidence was most rapid during the first 2 years after surgery and slowed during this study (Figures 2 and 3). The life-style demands of the patient seemed to be directly related to the amount of implant subsidence. One implant (8 years after insertion) was removed because of pain and stiffness that occurred after a hyperextension injury with fracture that the patient sustained while running 6 months before. At surgery there was a chronic ununited stress fracture of the volar base of the proximal phalanx with shifting of the implant stem into the stress fracture without any visible reactive synovitis. One patient had a transfer metatarsalgia involving the second metatarsal. Four great toes in three patients with the greatest subsidence had mild great toe clawing and no visible great toe push-off during normal walking (Table 3).

One patient developed superficial full-thickness ulcerations at the sites of the ankle block needle insertions. Over a year was required for the largest (1.5-in) ulceration to heal by scarring. The patient had a similar procedure on his other great toe with no problems. One patient developed a scar contracture with hyperextension of the great toe.

At last followup, 37 to 105 months postoperatively, pain was absent in six toes, mild and occasional in five toes, moderate and daily in one toe, and severe with vigorous activity in one toe. Activity was without limitations in 12 great toes. One woman required the use of comfort shoes (extra depth with anatomic toe boxes). The rest of the patients, two of whom were women with thee implants, were able to wear any shoes. One man required removal of the implant with an interpositional arthroplasty after a fracture and painful nonunion. One patient had severe restriction of interphalangeal joint motion for unknown reasons. All 13 first metatarsophalangeal joints were stable on physical examination. Calluses were not present on any of the 13 toes at followup. All first metatarsophalangeal joints were clinically well aligned (Table 4).

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Table 3:

Postoperative short-term and mid-term data

Pt #	Hospital	Infection	Suture (days)	Discontinued open-toed shoe (days)	All shoes (weeks)	RTW (days)	Full duty (months)	Final evaluation (months)	Post-operative Koenig toe score	Post-operative AOFAS score	Plantar-flexion (PF)	Dorsiflexion (DF)	Total flexion (TF)	Satisfied
1	No	No	21	25	16	31	3	105	74	85	10	30	40	Yes
2	No	No	13	42	8	25	4	96	65	66	15	45	60	No
3	No	No	20	56	12	21	4.5	79	98	90	0	50	50	Yes
4	No	No	11	21	12	22	3	75	98	95	10	53	63	Yes
5	No	No	14	42	6	56	2	51	94	95	10	55	65	Yes
6	No	No	13	42	40	56	2	51	92	88	10	55	65	Yes
2	No	No	12	42	8	45	5	89	92	85	0	45	45	Yes
1	No	No	21	49	15	35	5.5	70	84	85	10	40	50	Yes
7	No	No	9	28	28	49	8	52	86	90	30	80	110	Yes
8	No	No	13	56	12	24	2	65	92	95	0	40	40	Yes
6	No	No	13	42	40	56	10	41	94	85	15	55	70	Yes
9	No	No	11	35	16	4	4	37	82	70	−10	60	50	No
10	No	No	12	42	8	12	10	46	94	95	15	60	75	Yes
Average			14	40	17	34	5	65.9	88.1	86.5	8.8	51.4	60.2	85%

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Table 4:

Postoperative mid-term radiographic grading and complications

Pt #	Radiographic grading	Complications	Treatment of complication	End result of complication and treatment
1	Grade 2	None	N/A	N/A
2	Grade 4b	Jammed toe running 6 months previously with ununited fracture	Remove implant and fracture fragment	Running 6 weeks after removal
3	Grade 3a	None	N/A	N/A
4	Grade 3a	After 32 months second metatarsalgia	Second metatarsalgia: 2nd metatarsal Weil Osteotomy	Resolved
5	Grade 3a	None	N/A	N/A
6	Grade 3a	None	N/A	N/A
2	Grade 3b	None	N/A	N/A
1	Grade 3a	Superficial ankle ulcers from ankle block	Debridement & secondary closure	1+ years for ulcers to heal
7	Grade 2	Sprained toe 4 weeks postoperatively with 1 mm lucency stem	Decrease activities until symptoms are gone next 6 weeks	Gradual resolution symptoms
8	Grade 2	None	N/A	N/A
6	Grade 3a	None	N/A	N/A
9	Grade 3a	Mild extension of great toe	Observe	Decreased great toe push-off
10	Grade 3a	1/2 mm lucent stem, hyperextension tight tendon, capsule & skin	Z-Plasty tendon, skin & capsule	Patient happy and toe more functional

Using the radiographic grading system, all 10 patients with 13 great toe implants were evaluated radiographically. Three toes had grade 2 changes 2.8 to 8.7 years postoperatively, eight toes had grade 3a changes 3 to 4.3 years postoperatively, one toe in a daily runner had grade 3b changes 7.4 years postoperatively, and one toe had grade 4b changes 8 years postoperatively (Table 3).

The Koenig Scores ranged from 65 to 98 points out of 100 (average 88). The AOFAS Forefoot Scores ranged from 70 to 95 points out of 100 (average 86). After the patient with the transfer metatarsalgia was treated with a Weil osteotomy, and the patient with the scar contracture was treated with a Z-plasty, all but two patients were satisfied with their results. One patient with moderate daily pain was not satisfied and would not do it again. One patient with two implants was satisfied with both implants until a running injury (7.5 years after insertion) resulted in removal of one implant 6 months later for painful nonunion. He is still satisfied with the other implant and has resumed running. The satisfaction rate at an average followup of 5.5 years was 85% (Table 2).

DISCUSSION

Operative treatment of symptomatic hallux rigidus may include resection arthroplasty (Keller procedure), ¹¹ cheilectomy with or without debridement and synovectomy, ^6,19 hemi-great toe replacement arthroplasty, ^{5,17,26,27,29} “total toe” replacement arthroplasty, ^12,14,15 arthrodesis, ^4,21 or soft-tissue interpositional arthroplasty. ³ Our active patients were dissatisfied with weakness and instability of the great toe after Keller resection arthroplasties. Cheilectomy with or without debridement and synovectomy currently is recommended as the treatment of choice in most patients especially those over 60 years of age. ^8,6,19,20 Resection of a large amount of the dorsal metatarsal surface with a closing wedge osteotomy of the proximal phalanx has been recommended to improve the longevity of the procedure and the dorsiflexion range of motion of the first MTP joint. ¹⁰ Early loosening and failure have been frequent with these “total toe” implants, and they are considered experimental. ^12,14,15 Arthrodesis has been advocated as a primary procedure and as a salvage procedure when other procedures have failed. ^18,21 Young, active patients and especially female patients are hesitant to accept arthrodesis of the great toe with its fixed position rigidity or limited shoe options. ⁴ Arthrodesis also may be difficult in patients with poor bone stock or other severe medical problems. Silastic great toe implants of the Swanson designs have been advocated since 1967, ^5,26,27 but these implants have resulted in high rates of complications and failures with poor resultant bone stock for salvage procedures. ²³ In 1987, Swanson developed a titanium version of the original Swanson silastic hemiarthroplasty design ^1,2,17 for replacement of only the articulating surface of the proximal phalanx.

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Fig. 3:

Anteroposterior and oblique radiographs of patient with titanium implant in place 4.25 years with moderate lucency and subsidence.