At final review, pain and activity levels were assessed using standardised questions for all cases. Patient satisfaction with their surgical outcome was recorded qualitatively as completely satisfied, satisfied with reservations or dissatisfied. Reasons for reservations and dissatisfaction were recorded. Cosmetic concerns, footwear fitting difficulties and post-operative complications were also recorded.
Twenty four cases (73%) reported they were completely satisfied with the results of their surgery, 8 cases (24%) were satisfied with reservations and 1 case (3%) reported they were dissatisfied (table 1). All cases agreed they would be happy to undergo surgery under similar circumstance again if required, i.e. under local anaesthesia on a day case basis.
The cases that were satisfied with reservation, complained of symptoms only improved by 60% in one case, continued footwear restrictions in 5 cases and in 2 further cases who were satisfied with reservations had undergone neuroma excision from the 3rd IM space but required revision surgery because of continued pain which was performed in one case at 9 years and in the other at 11 years. After further excision of nerve tissue, their symptoms resolved.
Table 1 – Patient satisfaction and reasons for reservations and dissatisfaction
Number of cases
|
Satisfied
|
Satisfied with reservations
|
Dissatisfied
|
24 cases (73%)
|
X
|
|
|
8 cases (24%)
|
|
5 footwear restrictions
2 revision surgery
1 symptoms only improved by 60%
|
|
1 case (3%)
|
|
|
1 No improvement of symptoms
|
The one dissatisfied case reported their symptoms were no better but at review this patient presented with 2nd MTP joint capsulitis which was treated successfully with orthotics, footwear advice and cortisone therapy. However, prior to undergoing neuroma surgery clinical diagnosis had been made and diagnostic ultrasound examination identified a 6mm neuroma. Subsequent histopathology confirmed a neuroma 15mm wide had been excised. A possible cause of continued pain was capsulitis due to reduced plantar fat pad following the neuroma excision as clearly the IM nerve is part of the plantar fat pad and removal of the neuroma can leave a reduced plantar fat pad.
Twenty six of the 33 cases in the cohort (26/33) recorded a visual analogue score prior to surgery. The size of the neuroma on pre-operative ultrasound examination and the size on post-operative histopathology was compared in order to test if there was any correlation between the size of the neuroma and pre-operative pain levels. A highly statistically significant correlation value of 0.74 p>0.001 was established (table 5).
Three outcomes were measured by the MOxFQ; pain, walking/standing ability and social interaction, with the lower the score, the greater the improvement in the patients symptoms. The mean average scores for the 3 outcomes were pain 9.5/100, walking/standing 7.5/100 and social interaction 5/100. Additionally, 67% of patients (14/21) reported a score of 0 for pain and walking/standing and 76% (16/21) of patients reported a score of 0 for social interaction outcomes.
Patients were asked if their pain was better than pre-operative with 32/33 (97%) reporting they were improved; however the one case with continued capsulitis pain considered they were no better.
Cosmetically, 100% of patients were happy with the appearance of their foot and none had any concerns about the post-operative scar.
Beech et al 2000 reported a loss of sensation to the adjacent toes has been found to effect up to 59% of patients following neuroma excision [9]. All the patients in this study were sensate to a 10g monofilament plantar and dorsal to the area of surgery and adjacent toes. However, 16/33 (48%) patients reported a perception of altered sensation or ‘numbness’ in the adjacent toes. Altered sensation in the toes was recorded in 5/10 (50%) of 2nd IM space neuroma excisions and 11/23 (48%) of 3rd IM space neuroma excisions, however no case perceived this to be a problem.
All patients reported no activity restrictions at long-term follow-up whilst 100% of patients had reported footwear restrictions prior to surgery, only 1/33 (3%) reported footwear restrictions at long-term follow-up which was the patient previously described as being confined to a trainer/sport shoe.
We attempted to determine if neuroma surgery success could be predicted by considering the following four issues;
- Is the surgical outcome better when the neuroma is larger when measured on pre-operative ultrasound examination? Could it be that the larger the neuroma the more certain the diagnosis and the less likely the patient is suffering from another cause of forefoot pain? Unfortunately the number of the cases in this series was not sufficient to determine any statistically significant relationship between the size of the neuroma lesion and the subsequent surgical outcome (table 3).
- Does the pre-operative pain level relate to the outcome of surgery based on post-operative patient satisfaction? No obvious correlation was found in this series of cases (table 4).
- Does the level of pre-operative pain relate to the size of the neuroma measured on pre-operative ultrasound? When the size of the neuroma measured on ultrasound was correlated with the pre-operative visual analogue scores there was a strong correlation between size of the neuroma and the level of symptoms with neuromas greater than 7mm in diameter causing high levels of pain. In line with other studies surgical excision of neuromas measuring less than 6mm on pre-operative ultrasound is likely to have an unpredictable outcome [16] (table 5).
- Does the size of the neuroma on pre-operative ultrasound reflect the size of the neuroma measured histopathologically after excision? A weak statistically significant correlation was found between ultrasound measurement and histopathological measurement of the neuroma (table 6).
Table 2 – a comparison of studies looking at the outcomes of neuroma surgery.
Year
|
Study
|
Cohort
|
Mean follow-up (months)
|
Result
|
Complications
|
2019
|
Coutts and Kilmartin
|
33
|
106
|
73% totally satisfied
24% satisfied with reservations
3% dissatisfied
97% better from surgery
100% happy with appearance of foot
Footwear fitting improved
0% activity restrictions
|
48% numbness
6% recurrence of symptoms
|
2016
|
Flanagan and Reilly [19]
|
48
|
6
|
95% better or much better
|
2.4% recurrence of symptoms
2.4% no improvement
4.7% scar hypertrophy (plantar incision)
Numbness not reported on
|
2011
|
Lee, Kim, Young, Park, Kim, Jegal [20]
|
20
|
126
|
31% completely satisfied,
69% satisfied with minor and major reservations.
|
85% numbness
33% footwear restriction
18% activity restriction
|
2010
|
Pace, Scammell, Dhar [15]
|
82
|
54
|
82% excellent or good results
10% fair results with restriction of activities or pain
|
8% had no improvement
71% had footwear restrictions
|
2008
|
Womack et al [21]
|
120
|
66
|
50% good results,
10% fair results,
40% poor results (based on non-validated clinical scoring system)
|
78% numbness
Revision procedure excluded and number not noted.
|
2004
|
Giannini, Bacchini, Ceccarerelli, Vannini [22]
|
63
|
47
|
68% pain free
90% increase in activity
Footwear fitting improved
50% excellent results
16% good results
20% fair results
3% poor results
(based on non-validated clinical scoring system)
|
38% numbness
|
2004
|
Stamatis and Myerson [23]
|
49
|
40
|
31% completely satisfied
26.5% satisfied with minor reservations
20% satisfied with major reservations
22% dissatisfied
|
65% numbness
59% moderate or severe restriction of footwear
16% moderate restriction of activity
12% CRPS (no diagnostic criteria noted)
|
2001
|
Coughlin and Pinsonneault [24]
|
71
|
70
|
85% high patient satisfaction
65% pain free
|
70% mild/major footwear restrictions
51% numbness
|
2000
|
Beech, Rees and Tagoe [9]
|
34
|
27
|
47% completely satisfied,
47% satisfied with reservations.
91% better from surgery
|
59% numbness
6% dissatisfied
|
1996
|
Benedetti, Baxter and Davis [25]
|
19
|
69
|
53% complete resolution of pain
31% minimal residual symptoms
|
16% continued significant pain
Some degree of numbness reported in all patients
|
1995
|
Wilson and Kuwada [26]
|
59
|
180
|
68% complete pain relief
25% mild pain relief or pain progressively decreasing
|
10% stump neuromas
5% revision rate
2% no pain relief
|
1995
|
Schroven and Geutjens [27]
|
32
|
45
|
60% pain free
22% substantial improvement in pain
18% only minor improvement in pain
|
70% restriction of footwear
60% had to wear adaptive footwear or orthotics Numbness not reported
|
Table 3 - Pre-operative size on ultrasound compared to satisfaction rates N=23
Size of neuroma on ultrasound
|
Number of cases
|
Totally satisfied
|
Satisfied with reservation
|
Dissatisfied
|
4mm
|
1
|
1 (100%)
|
|
|
5mm
|
4
|
2 (50%)
|
2 (50%)
|
|
6mm
|
3
|
3 (100%)
|
|
|
7mm
|
5
|
4 (80%)
|
1 (20%)
|
|
8mm
|
5
|
5 (100%)
|
|
|
9mm
|
2
|
1 (50%)
|
1 (50%)
|
|
10mm
|
3
|
1 (33%)
|
2 (66%
|
|
Table 4 – Pre-operative VAS pain score compared to patient satisfaction compared N=24
VAS pain score pre-operatively
|
Totally satisfied
|
Satisfied with reservations
|
Dissatisfied
|
4 (n=1)
|
|
1
|
|
5 (n=3)
|
2
|
|
1
|
6 (n=10)
|
9
|
1
|
|
7 (n=2)
|
1
|
1
|
|
8 (n=3)
|
3
|
|
|
9 (n=4)
|
2
|
2
|
|
10 (n=1)
|
|
1
|
|
Table 5 – Correlation between neuroma size as measured on ultrasound and pre op VAS score. Pearson correlation r=0.74, p<0.001
Size of neuroma on ultrasound
|
Number of cases
|
Range of VAS
|
Mean of VAS (0-10)
|
4mm
|
1
|
5
|
5
|
5mm
|
4
|
5-7
|
6
|
6mm
|
3
|
6
|
6
|
7mm
|
5
|
4-6
|
5.6
|
8mm
|
5
|
6-9
|
7.6
|
9mm
|
2
|
8-9
|
8.5
|
10mm
|
3
|
9-10
|
9.3
|
Table 6 - Size of neuroma on ultrasound pre-operatively compared to post-operative histopathology report N=21. Pearson correlation r=0.43, p<0.05.
Size of neuroma on ultrasound
|
Number of cases
|
Mean size of neuroma on histopathology
|
Range of size of neuroma on histopatholgy
|
Difference ultrasound to histopathology
|
4mm
|
1
|
4mm
|
4mm
|
0mm
|
5mm
|
4
|
7.5mm
|
6-9mm
|
2.5mm
|
6mm
|
2
|
8mm
|
8mm
|
2mm
|
7mm
|
4
|
8.5mm
|
6-10mm
|
1.5mm
|
8mm
|
5
|
10mm
|
5-13mm
|
2mm
|
9mm
|
2
|
9mm
|
8-10mm
|
0mm
|
10mm
|
3
|
9mm
|
7-11
|
-1mm
|