- Email: [email protected]
Correction of hallux abductus valgus by Mitchell's metatarsal osteotomy: comparing standard fixation methods with absorbable polydioxanone pins
neFoor(1997)7,121-125 0 1997 Pearson Professmnal Ltd
Correction of hallux abductus valgus by Mitchell’s metatarsal osteotomy: comparing standard fixation methods with absorbable polydioxanone pins T. D. Prior, D. L. Grace, J. B. MacLean, P W. Allen, P G. Chapman, A. Day Department of Foot Health, St Leonard’s Primary Health Care, London, UK SUMMARY Thirty-nine Mitchell’s first metatarsal osteotomies were performed in 28 individuals with hallux abductus valgus at two centres. Seventeen osteotomies were stabilized with standard fixation (Vicryl@ bone suture or K wire) and 22 were fixated with absorbable polydioxanone Orthosorb@ Absorbable Pins (Johnson &Johnson Orthopaedics, Bracknell, UK). Patients were assessed preoperatively and at 3, 6 and 12 months postoperatively. Clinical evaluation was undertaken by an independent assessor unaware of the fixation method with radiographic assessment performed by the consultant. On review, one patient (one foot) that received absorbable fixation was lost to follow-up and another was last seen 4 months postoperatively. Average follow-up was 10.7 months (2-24 months). There was no statistical difference between the two groups in terms of age or weight. Statistical analysis by Mann-Whitney U test revealed no significant difference between the treatment and control groups for first metatarsophalangeal joint (MTPJ) range of motion, hallux valgus angle, intermetatarsal angle, hallux rotation and first to second metatarsal length ratio both preoperatively and postoperatively. Analysis of the patients combined by signed rank test revealed no significant change in the first MTPJ range of motion but there was a significant reduction in the hallux valgus angle, intermetatarsal angle, hallux rotation and first to second metatarsal ratio following surgery. The average postoperative hallux valgus angle (17.1”) suggests that the Mitchell’s metatarsal osteotomy is less effective for large preoperative deformities. There was no evidence of foreign body reaction, persistent or increased pin tract lucency or sinus formation in any patients receiving absorbable fixation. One foot required removal of the K wire fixation. In conclusion, absorbable polydioxanone pins present no additional complications to those associated with standard fixation methods and avoids the possible need for a second procedure to remove metalwork.
INTRODUCTION
are followed by 6 weeks’ immobilization. Bone suture provides approximation of the osteotomy, however, the risk of displacement is significant. Internal screw fixation can be difficult due to the relatively small distal fragment. This increases the risk of fragmentation, and the location of the screw near the metatarsal head often necessitates removal at a later date. K wire fixation is adequate if two are used but a single wire risks rotation of the distal fragment. There is a risk of infection at the exit site of the K wire unless it is left beneath the skin cut flush to bone. However, this often necessitates removal at a later date. These disadvantages could be overcome by the use of an absorbable pin. Two pins would provide improved fixation for the requisite 6-week period and the need for a further operation to remove the pins is obviated. Poly-para-dioxanone (PDS) is a well-characterized absorbable polymer which is widely used as a suture. Orthosorb Absorbable Pins (Johnson & Johnson Orthopaedics, Bracknell) are currently available in many countries including the USA and Germany, and
The Mitchell’s metatarsal osteotomy is a procedure which is often attributed to Mitchell et al’ although it was described by Hawkins et a1,2 of which Mitchell was an author. In these original descriptions of the procedure, the osteotomy is held in place with a suture across the bone section, followed by a B-week period of immobilization. Mitchell used chromic catgut for the suture when describing the procedure in 1958. Maintaining the corrected position is a recognized problem of the procedure. Valgus displacement results in recurrence of the deformity, whereas dorsal displacement or angulation results in an alteration in the loadbearing in the foot with subsequent metatarsalgia. There are three main methods used to stabilize the osteotomy, each with disadvantages and all of which Correspondence to T D Prior BSc (How) Department of Foot Health, St Leonard’s London Nl SLZ, UK.
FPod A MChS, Primary Health
Care,
121
122
The Foot
have completed clinical trials in the UK for the fixation of small bone and osteochondral fragments. This study assessed the efficacy and safety of the Orthosorb Absorbable Pin in the Mitchell’s metatarsal osteotomy. A randomized single-blind study comparing the results of this osteotomy for hallux valgus in two groups of patients in whom fixation of the osteotomy site was either traditional (bone suture or K wire) or the Orthosorb Absorbable Pin was undertaken at two sites. MATERIALS
AND METHODS
Orthosorb Absorbable Pins are composed of polydioxanone stained with D&C Violet No. 2 dye (this material is sometimes referred to as PDS in the literature). The pins are 1.3 mm in diameter and 40 mm in length and are either straight or tapered. The tapered pin is attached to a K wire for application. The pins are presterilized by ethylene oxide gas. Patients of either sex between the ages of 18 and 65 years with hallux valgus and no significant radiological evidence of degenerative disease at the first metatarsophalangeal joint (MTPJ) were included in the study Patients outside this age range, with skeletal immaturity, infection near the surgical site, psychosocial disorders, rheumatoid arthritis, peripheral vascular disease or significant radiological evidence of degenerative joint disease were excluded from the study. Ethics committee approval was obtained and all patients signed informed consent forms before participating. Initial assessment for inclusion was performed Table
l-The
radiographic
and clinical
by the operating surgeon and a clinical evaluation was performed by an independent assessor. Patients were randomized at surgery into a treatment (Orthosorb Absorbable Pin) and control group (standard technique). A Mitchell’s metatarsal osteotomy was performed with follow-up care at the surgeons’ discretion. Patients were scheduled for review at 3,6 and 12 months postoperatively by the consultant surgeon and independent assessor. However, owing to the difficulties in patients attending clinics and failure of attendance at the required appointment, the review periods varied. The independent assessor was blind to the fixation device employed. Clinical and radiological measurements and observations were recorded and are summarized in Table 1. RESULTS
A total of 39 feet (28 patients) underwent surgery. Ten surgeons, from trainee to consultant level, performed surgery and an even distribution was achieved for the two groups between the two sites. Straight and tapered Orthosorb Absorbable Pins were used in the treatment group and Vicryl bone suture and K wires were used in the control group. The average final follow up was 10.7 months (2-24 months) and there was no significant difference between the two groups regarding age, weight and sex (Table 2). The radiological and clinical measurements were analysed statistically to identify any significant difference between the two groups preoperatively (Table 3)
measurements
and observations
recorded
Measurement/observation Radiological Intermetatarsal Hallux valgus 1:2 metatarsal
(IM) angle (HV) angle (Met) length
degrees degrees ratio*
Clinical First MTPJ dorsiflexion First MTPJ plantarflexion First MTPJ range of motion Hallux rotation First MTPJ pain (patient) First MTPJ pain on exam Metatarsalgia Walking ability Cosmetic appearance * The
Table
2-Age,
12 metatarsal
weight
length
degrees degrees degrees degrees none/occasional/on walking/at rest o/+/++/+++ none/slight/less than 1 hour walking full/some hmitation/marked limitation satisfactory/slight reservation/unsatisfactory ratio
was used as X-ray
and sex for the treatment Age (years)
Treatment mean (s.e) Control mean (s.e)
and control Weight
magnification
was not standardized
groups (kg)
38.8 (3.7) 44.1 (3.9)
64.3 (2.0) 70.7 (4.8)
t-test P = 0.338 not significant
t-test P = 0.184 not significant
Sex
Fishers
M
F
1 3
21 14
exact test P = 0.21 not significant
Correction of hallux abductus valgus Table &Control
vs treatment group preoperatlvely. All statistical analyses by Mann-Whitney Control
IM angle HV angle 1:2 Met ratio 1st MTPJ Dors 1st MTPJ Pl. 1st MTPJ ROM Hallux rotation
Table L-Control
Mean
SE
Number
17 17 16 17 17 17 17
13.4
0.8 1.9
21 21
0.02
21 22 22 22 21
7.1
8.4 66.3
4.7 7.3 2.3
Mean
SE
14.0
0.4
33.4 0.9 61.5 9.0 70.6 11.4
1.5
IM angle HV angle 1:2 Met ratio 1st MTPJ Dors I st MTPJ Pl. 1st MTPJ ROM Hallux rotation
Table 5-Preoperative
Control Mean
17
9.1
17 16 17
15.8 0.81
17
17 17
60.0 1.2 61.2 7.0
SE 0.7 2.2 0.02 2.7 3.8 4.9 2.2
Number
Treatment Mean
21 21 21 22 22 22 21
9.4 18.2 0.79 64.3 4.9 69.2 5.1
P
value
n.s 0.180 n.s 0.500 n.s 0.932 n.s 0.691 n.s 0.600 n.s 0.607 n.s 0.273
0.02 5.2 4.4 5.8 1.7
vs treatment group postoperatively. All statlstlcal analyses by Mann-Whitney Number
U test
S.E
P value
0.7 2.2
0.813 n.s 0.471 n.s 0.607 n s 0.427 ns 0.497 n.s 0.246 n.s 0.917 n.s
0.01 2.9 3.4 4.4 1.2
vs postoperative for all patients. All statistical analyses by Signed Rank test Number
I M angle HV angle I:2 Met ratio 1st MTPJ Dors 1st MTPJ PI. 1st MTPJ ROM Hallux rotation
57.9 10.9
U test
Treatment
Number
30.7 0.92
123
38 38 37
39 39 39 38
Preop Mean 13.7 32.2 0.90 60.0 8.7 68.7 11.2
SE
Number
Postop Mean
0.4 1.2
38 38 38 38 38 38 38
9.3 17.1 0.80 62.4 3.2 65.6 6.0
0.01 4.2 3.2 4.5 1.4
and postoperatively (Table 4). In addition, the two groups were amalgamated and analysed to identify any significant changes postoperatively (Table 5). No significant difference was observed between the two groups for each measurement both preoperatively and postoperatively. However, when the group was analysed as a whole, there was a significant reduction in the intermetatarsal angle, hallux valgus angle, hallux rotation and the length of the first metatarsal. This would be expected with a corrective procedure of this nature. The remaining clinical observations were analysed to compare the two groups (Table 6). However, these were not analysed as a complete group as they are subjective values and, therefore, of little scientific value in assessing the outcome of the procedure. No significant difference was observed between the two groups for all measurements both preoperatively and postoperatively. In addition to the clinical measurements, the radiographs were examined for changes in the density of the metatarsal head and bony union at the osteotomy site. Union was observed at the osteotomy site in 36 feet with two feet not demonstrating union. These two
SE
P
value
0.5 1.6 0.01 2.0 2.5 3.3
1.2
0.357 ll.s
feet were in the treatment group but the X-rays were at 3 and 4 months with no further follow-up available. There was no significant difference in metatarsal head density between the two groups (Table 7) with no instances of reduced density. Table 8 lists the observed complications in the two groups. All complications observed are common to this type of procedure. The infection observed was not related to the pin tract.
DISCUSSION
The use of absorbable pins has several advantages which have to be counterbalanced by the possible complications and side-effects; namely stabilization of the osteotomy site, bone-density changes and sterile abscess formation, Patton et al3 reported the results of the use of PDS pins for digital arthrodeses on 58 toes (19 patients). Good results were achieved in all cases and there were no instances of infection, foreign body reaction, vascular compromise or excessive swelling. Burnetti et al’ reported the results of the use of PDS pins for the
124
The Foot Table &Treatment vs control group both pre and postoperatively for subjective parameters. All statistical analyses by Fisher’s Exact test
Preop Treatment
Control First MTPJ pain Non/occasional Walking/rest First MTPJ pin on exam None/mild Moderate/severe Metatarsalgia None/slight < 1 hour walking Walking ability Full/some limitation Marked limitation Shoewear choice Any/some care in choice Difficulty Cosmetic appearance Satisfactory/sl. reservation Unsatisfactory
Unchanged Increased
Table
GObserved
15 2
Control
8 14
0.607
16
ns
1
13
16
0.544
17
4
6
ns
0
14
15
0265
16
3
7
ns
16 1
21 1
8
15
9
7
5
8 14
6
12
Treatment 20
P
value
0.419
1
ns
complications for the treatment and control
groups Control Swelling (12/12) Infection Pain at range of motion (6/12) Decreased range of motion (6/12) Delayed healing (3/12) Decreased first toe purchase (1202) Pain at operation site (6/12) K wire removal Cortisone injection Transfer pain Scar pain Nerve entrapment Deformity re-occurrence
value
11
Table 7-Metatarsal head density for treatment vs control group. Statistical analysis by Fisher’s Exact test
Control
P
Treatment 3
0
1
2
2 2
0 1
0
2
2
1 1 1 0 1 1
0 0 0 3
0 I
3
fixation of the Austin’s metatarsal osteotomy. They used two crossed pins for stabilization in 30 cases and reported no incidences of complications. Similarly, Heatherington et als found no incidences of displacement, delayed healing or osteonecrosis in 20 first metatarsal capital osteotomies. However, pin-track lucency persisted beyond 3 months in eight patients (40%), although all resolved. Four patients (20%) demonstrated increased pin-track lucency prior to resolution.
Postop Treatment
P
value
19 2
0.581
20 1
0.552
17 4
0.243
1
0.688
16
20
0.701
ns
1
1
ns
0.158 ns
15
18
0.607
2
3
ns
0.457
16
1
18 3
0.387
ns
ns
ns
ns
ns
Persistent and increased pin-track lucency was also reported by Friend et al6 when they used PDS for 21 fifth metatarsal osteotomies. They recorded eight (38%) cases of persistent lucency and five (24%) cases of increased lucency, but all were asymptomatic. While there were no instances of sterile abscess formation requiring drainage, there was movement of the pin in one case requiring a second operation to allow trimming and, in another case, the formation of an asymptomatic bone cyst around the pin site was observed. Jensen and Jensen’ compared the use of PDS with K wires for hand surgery and found that patients undergoing K wire fixation had a significantly increased rate of re-operation for removal, although this may be due to the nature of the surgery. Interestingly, they report a case of pin-track infection with PDS requiring surgery. However, in the discussion they recommend ‘the biodegradable pins should be cut flush to the osseous soft canals to avoid protusion of the material into the soft tissue as this may cause tethering of the sliding tissues and pin tract infection’, suggesting this was more due to surgical techniques than the pin itself. Kalla and Janzen’ report a case of foreign-body reaction when PDS was used for an Austin’s osteotomy. This was confirmed on needle aspirate and CT scan but there was no abscessformation. Similarly, Frederick et al9 report a case of foreign-body reaction when PDS was used to fixate an elevating V-osteotomy of the fourth metatarsal. This was confirmed by histopathology when the patient underwent a second procedure to correct a delayed union. While there was sinus formation and drainage of the wound, the sinus did not penetrate to the deep tissues.
Correction of hallux abductus valgus By comparison, polyglycolic acid (PGA), which is marketed as Biofix, has several reported instances of sterile abscess formation. Gerbert” reviewed six previous papers reporting the use of Biofix for foot and ankle surgery. The patient numbers ranged from 28-516 and the rate of sterile abscess formation ranged from 3-8%. In the same paper, Gerbert also reported the results of 48 Austin’s metatarsal osteotomies in which Biofix (23 cases) and Orthosorb (25 cases) were compared. The Biofix group had 7 (30%) cases of osteolysis and 1 (4%) case of sterile abscess formation, while there were no similar instances in the Orthosorb group. Parks and Nelson” reported that five (10.3%) patients from forty-nine cases developed an abscess requiring drainage when Biofix was utilized for fixation of first metatarsal capital osteotomies. They found that the average time to drainage was 78.6 days and postulate that the quicker degradation period of Biofix (90 days) compared to Orthosorb (180 days) may explain the abscess formation in the former. The results of this study are in keeping with previous literature indicating that there are no significant complications noted with the use of Orthosorb pins. Furthermore, the use of the Orthosorb pin had no detrimental effect on the outcome of the Mitchell’s metatarsal osteotomy in terms of angular correction and subjective clinical findings when compared to standard fixation techniques. Interestingly, while the hallux valgus angle was significantly reduced by surgery, the average postoperative angle of 17.1” is still abnormal if Piggot’s value of 15” is used to define abnormality.‘* This may indicate that the Mitchell’s metatarsal osteotomy is less appropriate for larger deformities. The reduction in the length of the first metatarsal is to be expected as this is a ‘step down’ osteotomy. Various complications were observed postoperatively but the relatively small numbers prevented statistical analyses between the two groups. The complications observed between the groups were consistent for this type of procedure. Mitchell’ reported the development or aggravation of metatarsalgia in 12 cases (12%) and this has become the most commonly quoted complication of this procedure. Metatarsalgia developed in 3 cases (13%) of the subject group which is comparable with those reported by Mitchell.
125
CONCLUSION The Mitchell’s osteotomy significantly reduces the intermetatarsal angle, hallux valgus angle, hallux rotation and the length of the first metatarsal. However, large deformities may not be fully correctable with this procedure. The Orthosorb Absorbable Pin is as effective at stabilizing the capital fragment in the Mitchell’s metatarsal osteotomy as standard fixation techniques and obviates the need for removal when compared to K wires. This and other studies provide no significant evidence of detrimental bone resorption or sterile abscess formation with the use of Orthosorb Absorbable Pins. ACKNOWLEDGEMENTS Many thanks to the numerous medical and administrative staff at Highlands Hospital. Enfield and Princess Alexandra Hospital, Harlow for their help with this study. Thanks to Johnson & Johnson Orthopaedlcs for their support.
REFERENCES 1 Mitchell C L, Fleming J L. Allen R, Glenney C, Sanford G A Osteotomy-bunionectomy for hallux valgus. J Bone Joint Surg 1958: 40-A: 41-58. 2 Hawkins F B, Mitchell C L, Hendrick D W. Correction of hallux valgus by metatarsal osteotomy. J Bone Joint Surg 1945; 227A: 387-394. 3 Patton G W, Shaffer M W, Kostakos D P. Absorbable pin: a new method of fixation for digital arthrodesis. J Foot Surg 1990; 29: 122-1’7. 4 Brunetti V A. Trepal M J, Jules K T. Fixation of the Austm osteotomy with bloresorbable pins. J Foot Surg 1991; 30: 56-64. 5 Heatherington V J, Scott L S, Wilhelm K R, Laporta D M, Nicklas B J, Absorbable fixation of first ray osteotomies. J Foot &Ankle Surg 1994; 33: 290-294. 6 Friend G, Grace K, Stone H A. L-osteotomy with absorbable fixation for correction of Tallor’s bunion. J Foot & Angle Surg 1993; 32: 14-19. I Jensen C H, Jensen C M. Biodegradable pins versus Kirschner wires in hand surgery. J Hand Surg 1996; 21B: 507-510. 8 Kalla T P, Janzen D L. Orthosorb: a case of foreign-body reaction. J Foot &Ankle Surg 1995; 34: 366-370. 9 Frederick J, Hulst T J. Sundareson A S. Foreign-body reaction to absorbable fixation devices: clinical correspondence. J Am Pod Med Ass 1996; 86: 396-398. 10 Gerbert .I Effectiveness of absorbable fixation devices in
Austin bumonectomies. J Am Pod Med Ass 1992; 82: 189-195. 11
12
Parks R M, Nelson G. Complications with the use of bioabsorbable pins in the foot. J Foot &Ankle Surg 1993; 153-161. Piggot H. Natural history of hallux valgus in adolescent and early life. J Bone Joint Surg 1960; 42B: 749-760.
Correction of hallux abductus valgus by Mitchell’s metatarsal osteotomy: comparing standard fixation methods with absorbable polydioxanone pins T. D. Prior, D. L. Grace, J. B. MacLean, P W. Allen, P G. Chapman, A. Day Department of Foot Health, St Leonard’s Primary Health Care, London, UK SUMMARY Thirty-nine Mitchell’s first metatarsal osteotomies were performed in 28 individuals with hallux abductus valgus at two centres. Seventeen osteotomies were stabilized with standard fixation (Vicryl@ bone suture or K wire) and 22 were fixated with absorbable polydioxanone Orthosorb@ Absorbable Pins (Johnson &Johnson Orthopaedics, Bracknell, UK). Patients were assessed preoperatively and at 3, 6 and 12 months postoperatively. Clinical evaluation was undertaken by an independent assessor unaware of the fixation method with radiographic assessment performed by the consultant. On review, one patient (one foot) that received absorbable fixation was lost to follow-up and another was last seen 4 months postoperatively. Average follow-up was 10.7 months (2-24 months). There was no statistical difference between the two groups in terms of age or weight. Statistical analysis by Mann-Whitney U test revealed no significant difference between the treatment and control groups for first metatarsophalangeal joint (MTPJ) range of motion, hallux valgus angle, intermetatarsal angle, hallux rotation and first to second metatarsal length ratio both preoperatively and postoperatively. Analysis of the patients combined by signed rank test revealed no significant change in the first MTPJ range of motion but there was a significant reduction in the hallux valgus angle, intermetatarsal angle, hallux rotation and first to second metatarsal ratio following surgery. The average postoperative hallux valgus angle (17.1”) suggests that the Mitchell’s metatarsal osteotomy is less effective for large preoperative deformities. There was no evidence of foreign body reaction, persistent or increased pin tract lucency or sinus formation in any patients receiving absorbable fixation. One foot required removal of the K wire fixation. In conclusion, absorbable polydioxanone pins present no additional complications to those associated with standard fixation methods and avoids the possible need for a second procedure to remove metalwork.
INTRODUCTION
are followed by 6 weeks’ immobilization. Bone suture provides approximation of the osteotomy, however, the risk of displacement is significant. Internal screw fixation can be difficult due to the relatively small distal fragment. This increases the risk of fragmentation, and the location of the screw near the metatarsal head often necessitates removal at a later date. K wire fixation is adequate if two are used but a single wire risks rotation of the distal fragment. There is a risk of infection at the exit site of the K wire unless it is left beneath the skin cut flush to bone. However, this often necessitates removal at a later date. These disadvantages could be overcome by the use of an absorbable pin. Two pins would provide improved fixation for the requisite 6-week period and the need for a further operation to remove the pins is obviated. Poly-para-dioxanone (PDS) is a well-characterized absorbable polymer which is widely used as a suture. Orthosorb Absorbable Pins (Johnson & Johnson Orthopaedics, Bracknell) are currently available in many countries including the USA and Germany, and
The Mitchell’s metatarsal osteotomy is a procedure which is often attributed to Mitchell et al’ although it was described by Hawkins et a1,2 of which Mitchell was an author. In these original descriptions of the procedure, the osteotomy is held in place with a suture across the bone section, followed by a B-week period of immobilization. Mitchell used chromic catgut for the suture when describing the procedure in 1958. Maintaining the corrected position is a recognized problem of the procedure. Valgus displacement results in recurrence of the deformity, whereas dorsal displacement or angulation results in an alteration in the loadbearing in the foot with subsequent metatarsalgia. There are three main methods used to stabilize the osteotomy, each with disadvantages and all of which Correspondence to T D Prior BSc (How) Department of Foot Health, St Leonard’s London Nl SLZ, UK.
FPod A MChS, Primary Health
Care,
121
122
The Foot
have completed clinical trials in the UK for the fixation of small bone and osteochondral fragments. This study assessed the efficacy and safety of the Orthosorb Absorbable Pin in the Mitchell’s metatarsal osteotomy. A randomized single-blind study comparing the results of this osteotomy for hallux valgus in two groups of patients in whom fixation of the osteotomy site was either traditional (bone suture or K wire) or the Orthosorb Absorbable Pin was undertaken at two sites. MATERIALS
AND METHODS
Orthosorb Absorbable Pins are composed of polydioxanone stained with D&C Violet No. 2 dye (this material is sometimes referred to as PDS in the literature). The pins are 1.3 mm in diameter and 40 mm in length and are either straight or tapered. The tapered pin is attached to a K wire for application. The pins are presterilized by ethylene oxide gas. Patients of either sex between the ages of 18 and 65 years with hallux valgus and no significant radiological evidence of degenerative disease at the first metatarsophalangeal joint (MTPJ) were included in the study Patients outside this age range, with skeletal immaturity, infection near the surgical site, psychosocial disorders, rheumatoid arthritis, peripheral vascular disease or significant radiological evidence of degenerative joint disease were excluded from the study. Ethics committee approval was obtained and all patients signed informed consent forms before participating. Initial assessment for inclusion was performed Table
l-The
radiographic
and clinical
by the operating surgeon and a clinical evaluation was performed by an independent assessor. Patients were randomized at surgery into a treatment (Orthosorb Absorbable Pin) and control group (standard technique). A Mitchell’s metatarsal osteotomy was performed with follow-up care at the surgeons’ discretion. Patients were scheduled for review at 3,6 and 12 months postoperatively by the consultant surgeon and independent assessor. However, owing to the difficulties in patients attending clinics and failure of attendance at the required appointment, the review periods varied. The independent assessor was blind to the fixation device employed. Clinical and radiological measurements and observations were recorded and are summarized in Table 1. RESULTS
A total of 39 feet (28 patients) underwent surgery. Ten surgeons, from trainee to consultant level, performed surgery and an even distribution was achieved for the two groups between the two sites. Straight and tapered Orthosorb Absorbable Pins were used in the treatment group and Vicryl bone suture and K wires were used in the control group. The average final follow up was 10.7 months (2-24 months) and there was no significant difference between the two groups regarding age, weight and sex (Table 2). The radiological and clinical measurements were analysed statistically to identify any significant difference between the two groups preoperatively (Table 3)
measurements
and observations
recorded
Measurement/observation Radiological Intermetatarsal Hallux valgus 1:2 metatarsal
(IM) angle (HV) angle (Met) length
degrees degrees ratio*
Clinical First MTPJ dorsiflexion First MTPJ plantarflexion First MTPJ range of motion Hallux rotation First MTPJ pain (patient) First MTPJ pain on exam Metatarsalgia Walking ability Cosmetic appearance * The
Table
2-Age,
12 metatarsal
weight
length
degrees degrees degrees degrees none/occasional/on walking/at rest o/+/++/+++ none/slight/less than 1 hour walking full/some hmitation/marked limitation satisfactory/slight reservation/unsatisfactory ratio
was used as X-ray
and sex for the treatment Age (years)
Treatment mean (s.e) Control mean (s.e)
and control Weight
magnification
was not standardized
groups (kg)
38.8 (3.7) 44.1 (3.9)
64.3 (2.0) 70.7 (4.8)
t-test P = 0.338 not significant
t-test P = 0.184 not significant
Sex
Fishers
M
F
1 3
21 14
exact test P = 0.21 not significant
Correction of hallux abductus valgus Table &Control
vs treatment group preoperatlvely. All statistical analyses by Mann-Whitney Control
IM angle HV angle 1:2 Met ratio 1st MTPJ Dors 1st MTPJ Pl. 1st MTPJ ROM Hallux rotation
Table L-Control
Mean
SE
Number
17 17 16 17 17 17 17
13.4
0.8 1.9
21 21
0.02
21 22 22 22 21
7.1
8.4 66.3
4.7 7.3 2.3
Mean
SE
14.0
0.4
33.4 0.9 61.5 9.0 70.6 11.4
1.5
IM angle HV angle 1:2 Met ratio 1st MTPJ Dors I st MTPJ Pl. 1st MTPJ ROM Hallux rotation
Table 5-Preoperative
Control Mean
17
9.1
17 16 17
15.8 0.81
17
17 17
60.0 1.2 61.2 7.0
SE 0.7 2.2 0.02 2.7 3.8 4.9 2.2
Number
Treatment Mean
21 21 21 22 22 22 21
9.4 18.2 0.79 64.3 4.9 69.2 5.1
P
value
n.s 0.180 n.s 0.500 n.s 0.932 n.s 0.691 n.s 0.600 n.s 0.607 n.s 0.273
0.02 5.2 4.4 5.8 1.7
vs treatment group postoperatively. All statlstlcal analyses by Mann-Whitney Number
U test
S.E
P value
0.7 2.2
0.813 n.s 0.471 n.s 0.607 n s 0.427 ns 0.497 n.s 0.246 n.s 0.917 n.s
0.01 2.9 3.4 4.4 1.2
vs postoperative for all patients. All statistical analyses by Signed Rank test Number
I M angle HV angle I:2 Met ratio 1st MTPJ Dors 1st MTPJ PI. 1st MTPJ ROM Hallux rotation
57.9 10.9
U test
Treatment
Number
30.7 0.92
123
38 38 37
39 39 39 38
Preop Mean 13.7 32.2 0.90 60.0 8.7 68.7 11.2
SE
Number
Postop Mean
0.4 1.2
38 38 38 38 38 38 38
9.3 17.1 0.80 62.4 3.2 65.6 6.0
0.01 4.2 3.2 4.5 1.4
and postoperatively (Table 4). In addition, the two groups were amalgamated and analysed to identify any significant changes postoperatively (Table 5). No significant difference was observed between the two groups for each measurement both preoperatively and postoperatively. However, when the group was analysed as a whole, there was a significant reduction in the intermetatarsal angle, hallux valgus angle, hallux rotation and the length of the first metatarsal. This would be expected with a corrective procedure of this nature. The remaining clinical observations were analysed to compare the two groups (Table 6). However, these were not analysed as a complete group as they are subjective values and, therefore, of little scientific value in assessing the outcome of the procedure. No significant difference was observed between the two groups for all measurements both preoperatively and postoperatively. In addition to the clinical measurements, the radiographs were examined for changes in the density of the metatarsal head and bony union at the osteotomy site. Union was observed at the osteotomy site in 36 feet with two feet not demonstrating union. These two
SE
P
value
0.5 1.6 0.01 2.0 2.5 3.3
1.2
0.357 ll.s
feet were in the treatment group but the X-rays were at 3 and 4 months with no further follow-up available. There was no significant difference in metatarsal head density between the two groups (Table 7) with no instances of reduced density. Table 8 lists the observed complications in the two groups. All complications observed are common to this type of procedure. The infection observed was not related to the pin tract.
DISCUSSION
The use of absorbable pins has several advantages which have to be counterbalanced by the possible complications and side-effects; namely stabilization of the osteotomy site, bone-density changes and sterile abscess formation, Patton et al3 reported the results of the use of PDS pins for digital arthrodeses on 58 toes (19 patients). Good results were achieved in all cases and there were no instances of infection, foreign body reaction, vascular compromise or excessive swelling. Burnetti et al’ reported the results of the use of PDS pins for the
124
The Foot Table &Treatment vs control group both pre and postoperatively for subjective parameters. All statistical analyses by Fisher’s Exact test
Preop Treatment
Control First MTPJ pain Non/occasional Walking/rest First MTPJ pin on exam None/mild Moderate/severe Metatarsalgia None/slight < 1 hour walking Walking ability Full/some limitation Marked limitation Shoewear choice Any/some care in choice Difficulty Cosmetic appearance Satisfactory/sl. reservation Unsatisfactory
Unchanged Increased
Table
GObserved
15 2
Control
8 14
0.607
16
ns
1
13
16
0.544
17
4
6
ns
0
14
15
0265
16
3
7
ns
16 1
21 1
8
15
9
7
5
8 14
6
12
Treatment 20
P
value
0.419
1
ns
complications for the treatment and control
groups Control Swelling (12/12) Infection Pain at range of motion (6/12) Decreased range of motion (6/12) Delayed healing (3/12) Decreased first toe purchase (1202) Pain at operation site (6/12) K wire removal Cortisone injection Transfer pain Scar pain Nerve entrapment Deformity re-occurrence
value
11
Table 7-Metatarsal head density for treatment vs control group. Statistical analysis by Fisher’s Exact test
Control
P
Treatment 3
0
1
2
2 2
0 1
0
2
2
1 1 1 0 1 1
0 0 0 3
0 I
3
fixation of the Austin’s metatarsal osteotomy. They used two crossed pins for stabilization in 30 cases and reported no incidences of complications. Similarly, Heatherington et als found no incidences of displacement, delayed healing or osteonecrosis in 20 first metatarsal capital osteotomies. However, pin-track lucency persisted beyond 3 months in eight patients (40%), although all resolved. Four patients (20%) demonstrated increased pin-track lucency prior to resolution.
Postop Treatment
P
value
19 2
0.581
20 1
0.552
17 4
0.243
1
0.688
16
20
0.701
ns
1
1
ns
0.158 ns
15
18
0.607
2
3
ns
0.457
16
1
18 3
0.387
ns
ns
ns
ns
ns
Persistent and increased pin-track lucency was also reported by Friend et al6 when they used PDS for 21 fifth metatarsal osteotomies. They recorded eight (38%) cases of persistent lucency and five (24%) cases of increased lucency, but all were asymptomatic. While there were no instances of sterile abscess formation requiring drainage, there was movement of the pin in one case requiring a second operation to allow trimming and, in another case, the formation of an asymptomatic bone cyst around the pin site was observed. Jensen and Jensen’ compared the use of PDS with K wires for hand surgery and found that patients undergoing K wire fixation had a significantly increased rate of re-operation for removal, although this may be due to the nature of the surgery. Interestingly, they report a case of pin-track infection with PDS requiring surgery. However, in the discussion they recommend ‘the biodegradable pins should be cut flush to the osseous soft canals to avoid protusion of the material into the soft tissue as this may cause tethering of the sliding tissues and pin tract infection’, suggesting this was more due to surgical techniques than the pin itself. Kalla and Janzen’ report a case of foreign-body reaction when PDS was used for an Austin’s osteotomy. This was confirmed on needle aspirate and CT scan but there was no abscessformation. Similarly, Frederick et al9 report a case of foreign-body reaction when PDS was used to fixate an elevating V-osteotomy of the fourth metatarsal. This was confirmed by histopathology when the patient underwent a second procedure to correct a delayed union. While there was sinus formation and drainage of the wound, the sinus did not penetrate to the deep tissues.
Correction of hallux abductus valgus By comparison, polyglycolic acid (PGA), which is marketed as Biofix, has several reported instances of sterile abscess formation. Gerbert” reviewed six previous papers reporting the use of Biofix for foot and ankle surgery. The patient numbers ranged from 28-516 and the rate of sterile abscess formation ranged from 3-8%. In the same paper, Gerbert also reported the results of 48 Austin’s metatarsal osteotomies in which Biofix (23 cases) and Orthosorb (25 cases) were compared. The Biofix group had 7 (30%) cases of osteolysis and 1 (4%) case of sterile abscess formation, while there were no similar instances in the Orthosorb group. Parks and Nelson” reported that five (10.3%) patients from forty-nine cases developed an abscess requiring drainage when Biofix was utilized for fixation of first metatarsal capital osteotomies. They found that the average time to drainage was 78.6 days and postulate that the quicker degradation period of Biofix (90 days) compared to Orthosorb (180 days) may explain the abscess formation in the former. The results of this study are in keeping with previous literature indicating that there are no significant complications noted with the use of Orthosorb pins. Furthermore, the use of the Orthosorb pin had no detrimental effect on the outcome of the Mitchell’s metatarsal osteotomy in terms of angular correction and subjective clinical findings when compared to standard fixation techniques. Interestingly, while the hallux valgus angle was significantly reduced by surgery, the average postoperative angle of 17.1” is still abnormal if Piggot’s value of 15” is used to define abnormality.‘* This may indicate that the Mitchell’s metatarsal osteotomy is less appropriate for larger deformities. The reduction in the length of the first metatarsal is to be expected as this is a ‘step down’ osteotomy. Various complications were observed postoperatively but the relatively small numbers prevented statistical analyses between the two groups. The complications observed between the groups were consistent for this type of procedure. Mitchell’ reported the development or aggravation of metatarsalgia in 12 cases (12%) and this has become the most commonly quoted complication of this procedure. Metatarsalgia developed in 3 cases (13%) of the subject group which is comparable with those reported by Mitchell.
125
CONCLUSION The Mitchell’s osteotomy significantly reduces the intermetatarsal angle, hallux valgus angle, hallux rotation and the length of the first metatarsal. However, large deformities may not be fully correctable with this procedure. The Orthosorb Absorbable Pin is as effective at stabilizing the capital fragment in the Mitchell’s metatarsal osteotomy as standard fixation techniques and obviates the need for removal when compared to K wires. This and other studies provide no significant evidence of detrimental bone resorption or sterile abscess formation with the use of Orthosorb Absorbable Pins. ACKNOWLEDGEMENTS Many thanks to the numerous medical and administrative staff at Highlands Hospital. Enfield and Princess Alexandra Hospital, Harlow for their help with this study. Thanks to Johnson & Johnson Orthopaedlcs for their support.
REFERENCES 1 Mitchell C L, Fleming J L. Allen R, Glenney C, Sanford G A Osteotomy-bunionectomy for hallux valgus. J Bone Joint Surg 1958: 40-A: 41-58. 2 Hawkins F B, Mitchell C L, Hendrick D W. Correction of hallux valgus by metatarsal osteotomy. J Bone Joint Surg 1945; 227A: 387-394. 3 Patton G W, Shaffer M W, Kostakos D P. Absorbable pin: a new method of fixation for digital arthrodesis. J Foot Surg 1990; 29: 122-1’7. 4 Brunetti V A. Trepal M J, Jules K T. Fixation of the Austm osteotomy with bloresorbable pins. J Foot Surg 1991; 30: 56-64. 5 Heatherington V J, Scott L S, Wilhelm K R, Laporta D M, Nicklas B J, Absorbable fixation of first ray osteotomies. J Foot &Ankle Surg 1994; 33: 290-294. 6 Friend G, Grace K, Stone H A. L-osteotomy with absorbable fixation for correction of Tallor’s bunion. J Foot & Angle Surg 1993; 32: 14-19. I Jensen C H, Jensen C M. Biodegradable pins versus Kirschner wires in hand surgery. J Hand Surg 1996; 21B: 507-510. 8 Kalla T P, Janzen D L. Orthosorb: a case of foreign-body reaction. J Foot &Ankle Surg 1995; 34: 366-370. 9 Frederick J, Hulst T J. Sundareson A S. Foreign-body reaction to absorbable fixation devices: clinical correspondence. J Am Pod Med Ass 1996; 86: 396-398. 10 Gerbert .I Effectiveness of absorbable fixation devices in
Austin bumonectomies. J Am Pod Med Ass 1992; 82: 189-195. 11
12
Parks R M, Nelson G. Complications with the use of bioabsorbable pins in the foot. J Foot &Ankle Surg 1993; 153-161. Piggot H. Natural history of hallux valgus in adolescent and early life. J Bone Joint Surg 1960; 42B: 749-760.