Plantar fat pad atrophy: a cause of metatarsalgia?

Analysis of Nonweightbearing MRI Fat Pad Thickness Under Central Metatarsals in Patients With and Without Metatarsalgia

BACKGROUND

Metatarsalgia is a common diagnosis for patients with forefoot pain. Many have proposed metatarsal fat pad atrophy is a cause of metatarsalgia and therefore have suggested fat grafting instead of distal metatarsal osteotomies to treat metatarsalgia. For fat grafting to be a viable treatment, fat pad atrophy should correlate with metatarsalgia. This study looked to determine the relationship between metatarsal fat pad thickness and metatarsalgia and the correlation between metatarsal fat pad thickness and patient-reported outcomes.

METHODS

We conducted a retrospective review of patients with metatarsalgia and those with foot or ankle osteoarthritis who had a nonweightbearing MRI performed between February 1, 2021, and March 1, 2023. Data collected included demographics, PROMIS scores, metatarsal fat pad thickness in the second and third rays of the affected foot, and thinnest area on coronal section, measured on MRI. Student t test was used to compare continuous variables, whereas the χ2 test was used to compare categorical variables. Multivariable linear regression models were used to control for potential confounding factors.

RESULTS

A total of 112 patients were included in this study. Patients with metatarsalgia were significantly more likely to have a lower body mass index (29.3 vs 32.0, P = .03) than patients with osteoarthritis, but this finding was not present when controlling for confounding variables. We found no significant difference in fat pad thickness between patients with metatarsalgia vs patients with foot or ankle osteoarthritis (P = .43). We found no correlation between metatarsal fat pad thickness and pain interference (P = .59), physical function (P = .64), or mobility (P = .94) PROMIS scores.

CONCLUSION

In this retrospective comparative study of a relatively small cohort we found no significant difference in metatarsal fat pad thickness for patients with metatarsalgia vs patients with foot and ankle osteoarthritis based on nonweightbearing MRI, and no association between metatarsal fat pad thickness and patient-reported outcomes.

LEVEL OF EVIDENCE

Level III, case control study.

Efficacy of Proprioceptive Training on Plantar Pressure and Jump Performance in Volleyball Players: A Proof-of-Principle Study

Volleyball players are often subject to micro-traumatisms of the heel fat pad and ankle injuries. Recently, mat-based proprioceptive training has assumed a key role in recovery from these disorders. Therefore, this proof-of-principle study aimed to assess the efficacy of proprioceptive mat training on plantar pressures and athletic performance in volleyball players. The participants included adult semi-professional volleyball players allocated into two groups: an experimental group, with mat-based proprioceptive and balance training, and a control group, with a sham protocol. For the outcome, we evaluated the barefoot plantar pressure, performing an analysis on a baropodometric resistive platform. The countermovement jump and squat jump were measured using an inertial measurement unit. Nineteen subjects were included in the two groups: the active proprioceptive group (n = 10) or the control group (n = 9). The results show a more uniform redistribution of loads with pressure hindfoot relief in the experimental group compared to the control group (p = 0.021, RBC = 0.67). Moreover, we observed a significant increase in peak landing force and high concentric power development in the experimental group compared to the controls. Focused proprioceptive management provided hindfoot load attenuation by stimulating higher peaks of concentric force in the experimental group compared to the sham group. Even though the study included a small sample, the results obtained in this proof-of-principle study suggest a positive role of proprioceptive stimulation in the inter-seasonal scenario for volleyball players to improve their jump performance and reduce the micro-traumatisms of the heel fat pad and the ankle injury rate. However, further studies performed on larger samples are needed to confirm these preliminary results.

Radiographic factors associated with painful callosities after forefoot surgery in patients with rheumatoid arthritis

OBJECTIVES

Operative procedures for rheumatoid forefoot deformities have gradually changed from arthrodesis or resection arthroplasty to joint-preserving surgery. Although joint-preserving arthroplasty has yielded good outcomes, painful plantar callosities may occur post-operatively. This study aimed to reveal the radiographic factors associated with painful callosities after joint-preserving surgery for forefoot deformities in patients with rheumatoid arthritis (RA).

METHODS

We retrospectively evaluated 166 feet in 133 patients with RA who underwent forefoot joint-preserving arthroplasty, including proximal rotational closing-wedge osteotomies of the first metatarsal, between January 2012 and December 2015. Logistic regression analysis was performed with the objective variable set as the presence/absence of painful plantar callosities at the final observation and the explanatory variables set as several radiographic factors, including post-operative relative first metatarsal length (RML), amount of dorsal dislocation of the fifth metatarsal (5DD), and arc failure of the lesser toes.

RESULTS

At the final follow-up, 42 of the 166 feet (25.3%) had painful callosities under the metatarsal heads post-operatively. Logistic regression analysis showed that the RML, 5DD, and lesser toes' arc failure were significantly associated with painful callosities.

CONCLUSIONS

We identified that RML, 5DD, and arc failure of the lesser toes were associated with painful plantar callosities after the surgery.

Use of hyaluronic acid gel filler versus sterile water in the treatment of intractable plantar keratomas: a pilot study

BACKGROUND

Intractable plantar keratoma is a common concern in the podiatric medical office. Different treatment options are available, ranging from trimming and padding to surgery. We sought to investigate the use of hyaluronic acid gel injections as a possible minimally invasive alternative in the treatment of intractable plantar keratomas.

METHODS

Seventeen patients with intractable plantar keratomas were randomly assigned to receive a hyaluronic acid gel injection or a sterile water injection at the site of a previously trimmed plantar lesion.

RESULTS

There was no significant difference between the two groups in the evaluation of pain and function at 12 weeks, but both groups showed a clinically relevant improvement. No significant change was observed in plantar tissue thickness in both groups. A minor adverse reaction was seen in the hyaluronic acid group.

CONCLUSIONS

The use of a hyaluronic acid gel injection at the site of a trimmed intractable plantar keratoma did not seem more effective than the use of a sterile water injection. Sterile water injections seemed safe and efficient in reducing pain associated with plantar keratomas. Further investigations should concentrate on whether these results are reproducible in a larger sample and on the most effective sequence of treatment.

A stereologic study of the plantar fat pad in young and aged rats

Plantar fat pad (PFP) is a tissue structure that absorbs the initial impact of walking and running and ultimately bears body weight at standing. This study was designed to quantify the histomorphological changes of the PFP in aged rats. The most medial PFP was dissected from the hind feet of young rats (4 months old, n = 6) and aged rats (24 months old, n = 6). Histological structure and cellular senescence of PFP were analyzed stereologically and histomorphometrically. Immunohistochemistry of matrix metalloproteinase 9 (MMP9) was also performed on PFP tissue sections. Compared with young rats, the thickness of epidermis, dermis and septa of the PFP were significantly reduced in the aged rats. The total volume of adipose tissue in the PFP of aged rats was only about 65% of that in the young rats. The microvascular density and the number of fat pad units (FPU), a cluster of adipocytes enclosed by elastin septa, in the PFP were unchanged in the aged rats. In the aged rats, the number of adipocytes per FPU was reduced but the number of simple adipocyte clusters, without surrounding septa, was increased. The shift of the types of adipocyte clusters in the aged PFP was accompanied by degradation of elastin fibers and increased expression of MMP9. In conclusion, the PFP, particularly the elastic septa, degenerates significantly in aged rats and this may contribute to the pathology of PFP-related diseases.

Plantar pressures and relative lesser metatarsal lengths in older people with and without forefoot pain

Forefoot pain is a common problem in older people. We determined whether plantar pressures during gait and the relative lengths of the lesser metatarsals differ between older people with and without plantar forefoot pain. Dynamic plantar pressure assessment during walking was undertaken using the Tekscan MatScan® system in 118 community-dwelling older people (44 males and 74 females), mean age 74 (standard deviation=5.9) years, 43 (36%) of whom reported current or previous plantar forefoot pain. The relative lengths of metatarsals 1-5 were determined from weightbearing X-rays. Participants with current or previous plantar forefoot pain exhibited significantly (p=0.032) greater peak plantar pressure under metatarsal heads 3-5 (1.93 ± 0.41 kg/cm(2) vs. 1.74 ± 0.48 kg/cm(2) ). However, no differences were found in relative metatarsal lengths between the groups. These findings indicate that older people with forefoot pain generate higher peak plantar pressures under the lateral metatarsal heads when walking, but do not exhibit relatively longer lesser metatarsals. Other factors may be responsible for the observed pressure increase, such as reduced range of motion of the metatarsophalangeal joints and increased stiffness of plantar soft tissues.

The use of collagen injections in the treatment of metatarsalgia: a case report

Metatarsalgia is an increasingly common condition seen in the outpatient setting. A number of conservative and surgical management options are available for this condition. We present an interesting case that was unsuccessfully treated with'dermal filler.' To our knowledge, we have not found any published material in peer-reviewed journals documenting the use of collagen injections in the treatment of metatarsalgia. The authors feel that the lesson learned from this case should be highlighted for other foot and ankle surgeons.

Is there histomorphological evidence of plantar metatarsal fat pad atrophy in patients with diabetes?

The etiology of diabetic foot ulceration remains incompletely understood. Among other factors such as foot deformity in the presence of neuropathy, plantar fat pad atrophy has been identified as a contributory factor in diabetic foot ulceration. An association between fat pad atrophy and diabetic foot ulceration has been documented by imaging and histomorphological analysis of the calcaneal fat pad. However, histomorphological analysis of the metatarsal fat pad has not been performed to date. The present study entailed 14 patients with diabetes and 14 nondiabetic controls and was aimed at documenting histomorphological evidence for presumed plantar metatarsal fat pad atrophy in patients with diabetes. Histological stains and computer-assisted planimetry were performed on samples of metatarsal fat obtained during forefoot surgery. The histomorphological and planimetric analyses of adipocyte cross-sectional area and nuclear density demonstrated no differences between patients with diabetes and control patients. Our findings demonstrate that systemic atrophy of the metatarsal fat pad is not present in the diabetic foot and may not explain the structural changes previously proposed by noninvasive imaging.

LEVEL OF CLINICAL EVIDENCE

3.