The natural history of tarsal tunnel syndrome in diabetic subjects

INTRODUCTION

Tibial nerve entrapment is highly prevalent in diabetic subjects, resulting in significantly more neuropathic complaints and concomitant sensory disturbances. The study aim was to assess the impact of tarsal tunnel syndrome (TTS) and sensory loss at baseline on incident diabetic foot ulceration (DFU) in diabetic patients, since decompressing the tibial nerve might change the natural history of the disease.

METHODS

In this study, 113 subjects with TTS (69 bilateral, 23 left-sided and 21 right-sided) participating in the prospective Rotterdam Diabetic Foot Study were compared to 303 diabetic controls without TTS, regarding incident DFU. Kaplan-Meier analysis and Cox's regression analysis were used to determine the independent hazard of baseline variables for new DFU.

RESULTS

The median observation period was 836.5 days (IQR, 459-1077.8). In bilateral TTS, 17.4% (95% CI: 8.4-26.3%) of subjects experienced DFU versus 8.3% (95% CI: 5.1-11.6%) in controls (left or right) during follow-up (p = 0.0036). In left-sided TTS, no subjects versus 6.2% (95% CI: 3.4-9.0%) in controls had DFUs (p = 0.243). Incident ulceration was seen in 14.3% (95% CI: -0.7% to -29.3%) of right-sided TTS subjects versus 4.1% (95% CI: 1.5-6.3%) in controls (p = 0.034). Besides HbA1c, diminished sensation at the hallux independently increased the risk of ulceration, in patients with (HR: 4.692, p = 0.003) and without (HR: 2.307, p = 0.002) prior DFU.

DISCUSSION

Elevated sensory thresholds in TTS render diabetic patients at a higher risk for DFU. With effective surgery, TTS is likely to be an amenable factor to potentially prevent diabetic foot disease and thereby reduce amputation risk.

LEVEL OF EVIDENCE

II.

Prevalence and morphology of the gastrocnemius tertius: anatomical study and literature review

BACKGROUND

The gastrocnemius muscle (GM) third head or gastrocnemius tertius (GT) is a well-described GM variant. The purpose of the current study was to investigate the GT prevalence and morphology (including the proximal and distal attachments, and relationship with the neurovascular structures) in a cadaveric Central European population.

METHODS

A total of seventy-three lower limbs were dissected and investigated for GT presence; when the variant was identified, morphometric measurements were obtained.

RESULTS

The GM third head was observed in 10.96% (8/73 cases) under the form of two different morphological variants. The commonest variant type (6 cases) with proximal attachment from the femur posterior surface and fused with the GM lateral head. The second variant type (2 cases) proximal attachment was from the femur posterior surface and fused with the GM medial head. To understand this variation, we performed a brief literature review with meta-analysis. The GT variant has been identified with a pooled prevalence of 4.34%, under great morphological variability.

CONCLUSION

Clinicians, especially orthopaedics, should be aware of this variant, as it has been proven to cause popliteal neurovascular compression.