“In-situ” Joint Preparation Technique for first Metatarsophalangeal Joint Arthrodesis: A Retrospective Comparative Study with “Flat-cuts” and “Cup-and-cone” Techniques
2Department of Orthopaedic Surgery, Chaim Sheba Medical Center, Israel
Background:
The most common joint preparation techniques mentioned in literature for 1st metatarsophalangeal (MTP) joint arthrodesis are “cup and cone” and “flat-cuts”. The third option of an “in-situ” technique, has rarely been studied. This study compares the clinical, radiographic, and patient-reported outcomes of “in-situ” joint preparation with traditional 1st MTP joint preparation techniques.
Methods:
The “in-situ” technique utilizes the same dorsal surgical incision as traditional techniques. Cartilage and osteophyte removal is carried out using standard techniques without the use of specific reamers or a sagittal saw. The arthrodesis is performed in-situ with the similar freedom of joint positioning as the cup and cone technique, and traditional fixation constructs are applied. In this study, A retrospective chart review was performed for patients who underwent 1st MTP joint arthrodesis between January 2015 and December 2019. The complication, revision, and non-union rates were examined in a multivariable logistic regression model. The patient-reported outcomes were analyzed in a repeated-measures general linear model. Analysis of variance and Receiver Operating characteristics were used to assess radiographic measurements.
Results:
A total of 408 primary 1st MTP joint arthrodesis cases in 377 patients were included. Overall, 262 “Flat-Cuts”, 126 “In-Situ” and 20 “Cup-and-Cone” cases were analyzed. Compression plate system was used in 343 cases and cross-screws in 65 cases. The mean follow-up time was 294 days (median 174, SD 303). The overall union rate was 91.3% and the overall revision rate was 8.7%. The regression models demonstrated that the joint preparation technique did not have a statistically significant impact on union rates (p=0.311) or revision rates (p=0.898). Diabetes Mellitus was the most powerful predictor of non-union (p<0.001, OR 6.558, 95% CI: 2.534-16.969) and revision (p=0.02, OR 3.662, 95% CI: 1.230-10.905). Sub-analysis of the “in-situ” technique, revealed that the cross-screw construct was significantly associated with non-union (p=0.033, OR 6.402, 95% CI: 1.163-35.224). However, the revision rate associated with non-union was similar between the different fixation constructs (p=0.923). Furthermore, the cross-screw construct was not significantly associated with a higher overall revision rate (p=0.460). The overall complication rate was similar between the joint preparation technique groups (p=0.379). The rate of transfer metatarsalgia was significantly higher in “flat-cuts” versus “in-situ” (p=0.015, OR 6.808, 95% CI: 1.460-31.744). A linear regression model demonstrated that Visual-Analogue-Scale, PROMIS-10 Physical, and PROMIS-CAT-Physical significantly improved at 6 weeks, 3 months, and at last follow-up in “flat-cuts” and “in-situ” (p<0.001, p=0.004, p=0.001 respectively), however, the improvement was comparable between the two joint-preparation techniques (p=0.078, p=0.806, p=0.100). “In-situ” technique resulted in significantly less mean 1st ray shortening (3.05 mm, SD 4.07) compared with “flat-cuts” technique (7.64 mm, SD 3.27), (p<0.001, 95% CI: 3.73-5.44), and comparable shortening to the “Cup-and-Cone” technique (2.793 mm, SD 2.55), (p=0.789, 95% CI: -1.62-2.13). In a Receiver Operating Characteristic analysis of transfer metatarsalgia and 1st ray shortening, the optimal diagnostic cut-off was 6.87 mm (LR 1.67, AUC 0.652, p=0.005, 95% CI: 0.56-0.74).
Conclusion:
“In-situ” joint preparation technique is a simple, safe, and cost-effective technique for 1st MTP joint arthrodesis. In our series, the “in-situ” technique had a similar or better complication profile than the other techniques, while providing similar patient-reported outcomes. The “In-situ” technique resulted in significantly less 1st ray shortening when compared to the “flat-cuts” technique. The first ray shortening was a predictor of transfer metatarsalgia. Although the cross-screw construct was associated with higher non-union rates, the overall revision rate for non-union was similar between the different fixation constructs.