Intramedullary sealing with a bone plug in total knee arthroplasty to reduce blood loss: a meta-analysis of randomized controlled trials

This systematic review and meta-analysis was performed following the PRISMA (preferred reporting items for systematic reviews and meta-analyses) Statement [10]. The following keywords and search combinations were used: (1) bone plug AND total knee arthroplasty (2) intramedullary sealing AND total knee arthroplasty. PubMed, Embase, Ovid, and the Cochrane Library were used for the search. Articles in any language published until May 2018 were included and analyzed.

After the initial search, all article titles and abstracts were screened independently by two authors. The full manuscripts of relevant articles were evaluated for suitability by the inclusion criteria. The inclusion criteria were as follows: (1) the study compared the efficacy of intramedullary bone plug in TKA with an unplugged opening, (2) the study should be performed in primary TKA, (3) the study should evaluate postoperative bleeding aspects, and (4) the study was randomized and controlled. The studies that did not meet these criteria were excluded. In case of disagreements of both reviewers, a discussion between both reviewers was done to get a consensus. The intervention group included patients who had TKA with an intramedullary bone plug. The control group included patients who had TKA without an intramedullary bone plug. The primary outcome was blood transfusion rate. The secondary outcomes were drained volume of blood and the reduction in hemoglobin level.

Both reviewers independently assessed the risk of bias and the quality of the studies using the Cochrane risk-of-bias tool [11] to evaluate randomized control trials (RCTs). The Cochrane Handbook for Systematic Reviews of Interventions was used to evaluate the quality of the studies. The assessments were evaluated for random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data addressed, selective reporting, and other biases.

Review Manager (RevMan, version 5.3. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014) was used to conduct this meta-analysis. The transfusion rate was calculated with risk difference and 95% confidence interval. The drain volume and hemoglobin reduction were evaluated with standardized mean differences and 95% confidence interval. Heterogeneity was evaluated by I². If I² was greater than 50%, the data were considered to be statistically significant heterogeneity. The random-effects model was then used for data analysis. On the other hand, if I² was less than 50%, the data analysis was done with the fixed-effects model.

A total of 97 relevant studies were identified through the initial search. Thirty-one studies were excluded because they were duplicates. The remaining 66 studies were evaluated according to the inclusion criteria. Finally, four studies were included for a systematic review and meta-analysis. The flow chart diagram of the search for studies and selection is shown in Fig. 1. There were 320 patients in the intramedullary bone plug group and 316 patients in the “no plug” group.

The characteristics of the included studies are reported in Table 1. There were four RCTs. The total number of subjects from all studies was 636 patients. In all studies, one group of patients had an intramedullary bone plug while in the other group the intramedullary canal opening was left open.

There were four RCTs. All studies used randomization methods. However, one study reported concealment of allocation [5]. Three studies reported blinding of the participants [5‐7], and three studies blinded the assessors [5, 7, 12]. There were no incomplete outcome data results in any of the studies. Quality assessments of the studies were evaluated and are summarized in Fig. 2.

Three studies with a total of 516 patients were evaluated for the postoperative transfusion rate comparisons between the intramedullary plug and no plug groups [5, 6, 12]. A fixed-effects model was used because homogeneity was found in the studies (χ² = 1.55, [p = 0.46]; I² = 0%). The pooled results demonstrated that patients with intramedullary plug had a lower rate of blood transfusion than patients with an unplugged intramedullary canal (p < 0.01) (Fig. 3).

Hemoglobin reduction after TKA was reported in three studies with 516 patients [5, 6, 12]. There was significant heterogeneity in the pooled data (τ² = 0.35; χ² = 18.45, df = 2 [p < 0.01]; I² = 89%). Therefore, a random-effects model was used to analyze the data. The analysis found that patients who had an open intramedullary canal had a higher level of postoperative hemoglobin reduction compared with patients in whom an intramedullary bone plug was used (p = 0.01) (Fig. 4).

Four studies with 636 patients reported the outcome of drain volume [5‐7, 12]. There was statistical evidence of heterogeneity between the four studies (τ² = 8827.59; χ² = 20.80, [p < 0.01]; I² = 86%). The patients who had intramedullary bone plug had no significant difference of drain volume comparing with patient who had an unplugged intramedullary canal (p = 0.07) (Fig. 5).