A Retrospective Analysis of the Modified Intervastus Approach

PATIENTS AND METHODS

A retrospective review of functional outcomes after TKA using the MIV approach was conducted; the study was approved by the University of Illinois Institutional Review Board. A total of 127 patients of mean age 66.75 years (range, 48–86 years) with primary osteoarthritis of the knee who were indicated for a total knee replacement with 1-year follow-up were included. The patient demographics are shown in Table 1.  All patients underwent TKA using the MIV approach described above by 2 experienced orthopedic surgeons at the same institution. Patients received spinal anesthesia and a periarticular pain block intraoperatively. A measured resection technique was used by 1 surgeon, and a gap-balancing technique by the other. Surgeon 1 used the Persona PS cemented knee system (Zimmer Biomet, and Surgeon 2 used the Sigma PS cemented knee system (Depuy). Patellar resurfacing was done in all cases. Patellar tracking was checked intraoperatively using the ‘no-touch’ technique, and the need for a lateral release was noted. Drains were removed on postoperative day 1. Oral opioids were given as needed. Intravenous antibiotics were continued for 24 hours. Oral anticoagulants were used for thromboembolism prophylaxis for 3 weeks. Patients were mobilized on the day of surgery with full weight-bearing under the supervision of an experienced physical therapist. Static and dynamic quadriceps exercises were started on the same day of surgery along with active knee ROM exercises. Pain score, extensor lag, ROM, walking ability, and complications were recorded in all patients.

Table 1. Patient Demographics

The visual analog score (VAS) was obtained preoperatively and recorded on postoperative day 1. Patient walking distance with assistance was measured on the day of surgery, after surgery, and on the day of hospital discharge. Patients were assessed preoperatively and postoperatively at 1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year for knee ROM. A one-way ANOVA was conducted to compare the preoperative and postoperative day 1 VAS with significance set at P < .05 (OriginPro 2015, OriginLab Corporation). Differences in knee ROM between preoperative and postoperative follow-up periods (1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year) were identified using a 1-way ANOVA with a post hoc Tukey test. Significance was set at P < .05.

RESULTS

All patients were able to fully straight-leg raise and demonstrate functional knee ROM by postoperative day 1. The patella tracked centrally in all patients, and none required a lateral retinacular release. The majority of patients were discharged in the first 48 hours after surgery on oral narcotics. None required IV narcotics during their hospital stay or a blood transfusion. Two cases were complicated by severe knee skin blistering postoperatively due to a reaction to an adhesive dressing; one was complicated by skin necrosis leading to a flap reconstruction that became infected, requiring a 2-stage revision. A separate case had an acute postoperative infection that required irrigation and debridement with polyethylene exchange. After a 12-week course of antibiotics, the infection was eradicated. All patients reported a high satisfaction rate during their acute postoperative phase.

Postoperatively, all patients were able to walk on the day of surgery either independently or with some assistance. On the day of surgery, 10% of patients were able to walk >200 feet, and this increased to 65% of patients able to walk >200 feet on the day of discharge (compare Figure 9A and Figure 9B).  Within 2 weeks of surgery, 30% of patients could walk independently (without assistive devices), and this number increased to 78% by 8 weeks after surgery (Figure 10).

Pain assessed using the VAS was lower on postoperative day 1 (3.17 ± 1.97) than the preoperative score (3.69 ± 2.22, P< .05). Overall, knee ROM significantly increased during the follow-up after surgery. Initially, the ROM decreased 1 week after surgery (90.82 ± 10.28) compared with preoperative ROM (101.04 ± 19.48, P < .001) (Figure 10).  At 2 weeks after surgery, knee ROM returned to the preoperative value (100.70 ± 13.36). By 6 weeks after surgery, knee ROM was 17° greater than the preoperative ROM (118.45 ± 11.89, P < .001). Knee ROM remained stable at 3- and 6-month assessments, and showed further improvement by 1 year (126.62 ± 9.81, P < .001) compared with the preoperative state (Figure 10). The net improvement in knee ROM was 25° of increased knee flexion by 1 year.

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