Three Intraoperative Methods to Determine Limb-length Discrepancy in THA

Abstract

Limb-length discrepancy (LLD) is a common concern for both surgeon and patient in the setting of elective total hip arthroplasty (THA). There is a paucity of evidence guiding surgeons to an optimal method for measuring intraoperative LLD and minimizing postoperative LLD. The primary objective of this prospective, randomized, double-blinded study was to determine which of 3 intraoperative methods used at the authors' institution was best correlated to postoperative radiographic LLD. From 2011 to 2012, 81 patients undergoing either primary (75) or revision (6) THA with an anterolateral (Watson-Jones) approach were prospectively randomized and received intraoperative measurement of LLD via 1 of 3 methods: abductor shuck (AS), tranosseous pins with calibrated caliper (TP), or patella electrocardiogram (EKG) leads (PL). Intraoperative measurements of LLD were compared to clinical and radiographic postoperative measurements of LLD, and absolute differences and correlation coefficients were calculated for each method. Overall, the mean LLD preoperatively was 8.09 mm, and mean radiographic LLD postoperatively was 4.20 mm. The AS method was associated with the highest correlation to postoperative radiographic LLD (R=0.360; P<.05), whereas the other methods had mildly positive but statistically insignificant correlations (TP R=0.275; P>.05; PL R=0.301; P>.05). The AS method best correlates to postoperative radiographic LLD among the 3 techniques, although all methods were positively correlated. Clinical measurements of LLD correlate poorly with radiographic measurements and may be of limited utility.

Intraoperative measurement of limb lengthening during total hip arthroplasty

“…The accuracy of this method seemed to be similar to that of other published techniques using a standard reference pelvic point, such as techniques based on a pin in the infracotyloid groove19 (1.49 mm) or on calipers10 (1.7 mm). Moreover, the absolute value of correlation between these two measurements was similar to that of other techniques, like those based on calipers ( r = 0.89, r = 0.93), navigation systems ( r = 0.88), or a pin in the infracotyloid groove ( r = 0.82) 101519…”

“…Many studies have been published, describing techniques about the management of LLD. These methods can be divided into four main categories: (1) Based on the preoperative templating to define the correct neck cut, the correct neck length of the femoral component (in case of a modular head) or the correct depth of insertion of the femoral component (by measuring the distance of the tip of the greater trochanter to the shoulder of the femoral component),5678 (2) based on the usage of a standard pelvic reference point and of a femoral reference point, and measurement of the distance of these two points as the limb length changes intraoperatively [the marking of the pelvic reference point and the measurement can be performed with the aid of calipers,91011121314151617 bented K-wire,18 suture (tied in the skin, in a K-wire, or in a pin),19 Steinman pin in the infracotyloid groove or screw above the superior acetabular rim,2021 (3) based on clinical tests intraoperatively such as the shuck test, the drop kick test, and the leg-to-leg comparison,152223 and (4) based on navigation system's measurements 16242526. In addition, some other techniques have been described, such as measuring the gap between the tenotomy limb edges of the abductor musculotendinous insertion on the greater trochanter15 or evaluating the level of the center of the head in relation to the tip of the greater trochanter with the aid of a plate in a femoral head slot 27…”

Accuracy of leg length and femoral offset restoration after total hip arthroplasty with the utilisation of an intraoperative calibration gauge

“…A total of 360 patients in the literature were operated on using intraoperative callipers with reference points usually within the iliac bone to avoid discrepancies (Tables 2 and 3). 15,22,23,[31][32][33][34][35] This appears to effectively minimise postoperative LLD but usually does not simultaneously evaluate recreation of femoral offset. The average LLD in the literature using an intraoperative calliper was calculated at 2.89 mm, which is comparable to the presented cohort (p = 0.102).…”

Double-Stitch Technique: A Simple and Effective Method to Minimize Limb Length Discrepancy after Total Hip Arthroplasty

“…In Group II, steps of standard posterior approach were followed and after insertion of acetabular and femoral components and reduction of hip joint, length of the limb was assessed by patellar palpation method 10. As before in Group I, adjustments were made on size of implants to achieve the desired limb length.…”