Surgical site soft tissue thickness as a predictor of complications following arthroplasty

Table 1 Soft-tissue thickness in total knee arthroplasty

Ref.	Type of study	n	Mean BMI	Mean age	Indications for surgery	Approach	STT measurement definition	Outcomes studied	Results	Inter-rater reliabilities	Challenges
Wagner et al[23]	Retrospective	528	35.5	57.8	Osteoarthritis	Not specified	PFTR measured from radiographs	SSI, BMI, PFTR	Significant association between higher PFTR and increased risk of SSI	Strong agreement (r = 0.952; P < 0.001)	Small number of infections, limited generalizability to non-obese populations
Watts et al[24]	Case-control	116	44.8	62.7	Osteoarthritis	Not specified	PPT and PTT measured from radiographs	SSI, reoperation risk, PPT, PTT	Higher PPT and PTT associated with increased risk of reoperation	Excellent (Pearson coefficients: PPT 095, PTT 098)	Retrospective design, small sample size, potential unaccounted variables
Vahedi et al[22]	Case-control	824	32.5	63.9	Osteoarthritis	Not specified	Medial STT at joint line on AP radiograph; Anterior STT 8 cm above joint line on lateral radiograph	PJI, STT, BMI	Higher medial and anterior STT associated with increased risk of PJI	Excellent (ICC: Anterior STT 094, medial STT 096)	Retrospective design, potential unmeasured confounders, variability in surgical techniques
Shearer et al[28]	Retrospective	4745	32.1	68.3	Osteoarthritis	Not specified	PPT; KAI	PJI, surgical duration	BMI > 35 was strongly associated with PJI; local adipose measures were not significant	Excellent for KAI (inter: 0.94, intra: 0.99), moderate for PPT (inter: 0.75, intra: 0.99)	Variations in measurement techniques, low incidence of PJI, retrospective design
Yu et al[25]	Retrospective	376	30.9	66.2	Osteoarthritis	Not specified	PASTI using femoral and tibial measurements	Minor and major wound complications	High PASTI (> 3.0) associated with more minor complications (tibial OR: 3.89, femoral OR: 2.09); no significant difference in major complications	Excellent for both femoral and tibial PASTI (inter: 0.980/0.984, intra: 0.985/0.967)	Retrospective design, accuracy dependent on standardized X-ray technique, limited by proper lateral radiographs only
Gupta and Kejriwal[26]	Retrospective	494	30.6	71.3	Osteoarthritis	Medial parapatellar	PPT and PTT	Superficial wound complications	PTT ≥ 12 mm associated with lower risk of superficial wound complications (RR: 0.54); PPT not significantly associated	Measurement reliabilities not evaluated in this study, but previous study by Watts et al. noted high reliabilities (PPT: Intra 095, inter 0.92; PTT: Intra 098, inter 0.96)	Retrospective design, non-standardized surgical techniques, dressing types, and rehabilitation protocols, small sample size, no comparison group for BMI ≥ 40 kg/m2
Secrist et al[27]	Retrospective	453	32.9	66	Osteoarthritis	Not specified	LEG ratio: Width of soft tissue envelope divided by bone width on lateral radiographs	90-day postoperative complications	No significant difference in LEG ratio between patients with/without complications; LEG ratio had no utility in predicting complications	Not specified	Retrospective design, novel measurement method not validated in previous studies, did not analyze intraoperative variables, limited to short-term complications

PFTR: Prepatellar fat thickness ratio; SSI: Surgical site infection; BMI: Body mass index; PTT: Pretubercular thickness; PPT: Prepatellar thickness; ICC: Intra-class correlation; PJI: Periprosthetic joint infection; STT: Soft-tissue thickness; KAI: Knee Adipose Index; PASTI: Preoperative Anterior Soft-Tissue Index; OR: Odds ratio; RR: Relative risk; LEG: Lower extremity girth.