Yes, Bunions Can Occur on the Lateral Side of the Foot
Yes, a bunion can absolutely occur on the lateral (outer) side of the foot—this is called a bunionette or "tailor's bunion," and it represents a distinct clinical entity characterized by a painful lateral prominence of the fifth metatarsal head 1, 2.
What Is a Bunionette?
A bunionette is a forefoot deformity presenting as a lateral, dorsolateral, or plantarlateral protuberance along the fifth metatarsal head 2. The condition results from a multifactorial anatomic interplay between fifth metatarsal bony morphology and forefoot soft-tissue imbalance 2. The deformity can manifest as:
- Head hypertrophy of the fifth metatarsal
- Lateral bowing of the fifth metatarsal shaft
- Splaying (widening) of the metatarsals
- Combinations of these patterns 3
Friction between the bony prominence, soft tissue, and constrictive footwear leads to keratosis (callus formation), inflammation, pain, and potentially ulceration 2.
Clinical Presentation and Assessment
The deformity affects nearly 25% of individuals in the general population 4. Key radiographic measurements include:
- Fourth-fifth intermetatarsal angle (M4M5): typically elevated from normal (~6°) to 10-13° in symptomatic cases 5
- Fifth metatarsophalangeal angle (M5P1): often increased to 16° or more 5
Important caveat: Don't focus solely on the fourth and fifth metatarsals. Research demonstrates that bunionette deformity involves splaying of all metatarsals and increased intermetatarsal angles between the second-third and third-fourth metatarsals as well 3. This whole-foot assessment is critical for surgical planning.
Treatment Approach
Conservative Management (First-Line)
Symptomatic bunionettes are usually responsive to nonsurgical management 2, which includes:
- Footwear modification (wider toe box, avoiding constrictive shoes)
- Orthoses and padding
- Activity modification
Critical limitation: No long-term studies demonstrate sustained symptom relief with conservative treatment alone 1.
Surgical Management (When Conservative Fails)
Surgical options include exostectomy and various metatarsal osteotomies (distal, diaphyseal, proximal) performed via open or minimally invasive surgery (MIS) techniques 1.
Complication Rates by Technique:
Open surgery 1:
- Proximal osteotomies: 22% complication rate
- Diaphyseal osteotomies: 21% complication rate (highest revision rate at 2%)
- Distal osteotomies: 11% complication rate
- Complication rates: 0-21.4%
- Nonunion rates: 0-5.6%
- Most common complication: hypertrophic callus formation (typically resorbs without intervention) 6
MIS appears to reduce wound-related and hardware complications compared to open techniques 1, though direct comparative studies are lacking.
Surgical Considerations:
- Distal osteotomies (most commonly used in MIS): Majority of studies (14/18) use unfixed distal osteotomy techniques 6
- Anatomic risk: The lateral dorsal cutaneous nerve (LDCN) is at significant risk during percutaneous approaches, averaging only 1.64 mm from the osteotomy site 4
- Fixation target: When using fixation, the dorsomedial quadrant of the fifth metatarsal head has the highest bone density (301 HU vs. 186-241 HU in other quadrants) and represents the optimal fixation site 7
Severity-Based Recommendations:
Critical pitfall: Minimally invasive techniques are not advisable for severe deformities 8. In one study, patients with high-grade deformities (types II and III) had significantly worse outcomes, with 9 patients (5 type II, 4 type III) stating they would not undergo the procedure again 8.
Best outcomes occur in mild to moderate deformities (type I and some type III cases), where good-to-excellent AOFAS scores (80-100) are achievable 8.
Clinical Outcomes
Both MIS and open techniques demonstrate statistically significant improvements in:
- Pain scores (VAS decreasing from 8/10 to 0.3/10) 5
- AOFAS scores (increasing from 58 to 97) 5
- Patient satisfaction (97.5% satisfied or very satisfied) 5
- Radiographic correction of M4M5 and M5P1 angles 6
However, the lack of high-quality prospective comparative trials prevents definitive conclusions about superiority of one technique over another 1.