In this study, there was no association between immediate revisions after primary THA and increased complication rates, particularly infection rates, within 2 years of the index procedure. Although dislocation remains an immediate postoperative concern, leg length discrepancy (LLD) is also a main cause of immediate revision. These results could assist surgeons in determining whether immediate revision is necessary, rather than waiting for discomfort at first weight bearing.

Revision surgeries remain a major challenge for surgeons and patients due to the higher 30 day mortality rate [18]. Postoperative complications and the subsequent need for revision also pose a greater economic burden to the healthcare system [19]. Revisions due to preventable causes, such as instability, are expected to increase in the future [20].

Some teams have used intraoperative radiographs [21, 22] or digital radiographic alignment software [23] to avoid implant misplacement or LLD. However, this requires an experienced team with intraoperative radiographs and increases operative time for each primary THA. Intraoperative radiographs may not be precise enough and may not be correlated with postoperative radiographs [24]. Due to the traction table, the authors were unable to take radiographs of both hips to check for LLD. Other teams have used a standard instead of a traction table to intraoperatively control lengths, with some reporting leg length reconstruction as more accurate in the traction table group (0.56 versus 1.78 mm)[25]. However, others have reported that both techniques provided equal results [5], and some have reported that leg length restoration was significantly more accurate without a traction table (2.4 versus 3.7 mm)[26].

According to some authors, revision of THA for LLD may not always be warranted due to the increased risk of complications associated with early revisions [9,10,11, 20]. Postoperative symptomatic LLD can have a negative impact on patient satisfaction, functional outcomes, and implant survival [27]. This “surgeon-controlled variable” can cause persistent pain, instability, and early failure due to impingement and increased surface wear [28]. Symptomatic LLD can also exacerbate lower back pain, further increasing the economic burden [29].

In our study, the rate of immediate revision after primary THA was 0.3%, which is relatively low. However, immediate revision should still be considered a serious option in clinical practice. Revision surgery, particularly for aseptic reasons, carries the risk of infection, which is the most feared complication. Studies based on insurance registries have reported an increased risk of infection following revision surgery. Goldman et al. [9] analyzed a cohort of 15,357 patients who underwent THA, of whom 211 required aseptic revision within 1 year of the index surgery. They found that aseptic revisions within the first year were associated with an 8- to 13-fold increase in periprosthetic joint infection (PJI) compared with the control group. At 2 years, the PJI rate was 0.2% in the control group, 4.8% in patients who underwent aseptic revision within 90 days [hazard ratio (HR) 8, p < 0.001], and 3.2% in patients who underwent aseptic revision between three and 12 months (HR 13, p < 0.001), in line with the findings of Quinlan et al.[11]. Out of 5500 primary THA from the Medicare and Humana databases, 550 patients who underwent early aseptic revision (within 1 year of index surgery) were analyzed. They found a significantly increased risk of infection at 1 year in the aseptic revision group when compared with the control group: 5.49% versus 0.91%, OR 5.61, p < 0.001 for the Medicare registry base, and 7.21% versus 0.68%, OR 11.34, p < 0.001 for the Humana registry base. They also reported that revisions performed within 90 days led to more infections than revisions performed within 1 year (11.76% versus 7.21%). Heckmann et al. and Schwarz et al. discovered a dose effect depending on the timing of revision after index surgery [10, 20]; the earlier the revision was performed, the higher the risk of infection, with an infection rate of 14.7% for revisions within the first month and 10.6% between 2 and 3 months. This effect decreased until 12 months after the index surgery.

The study found no infections associated with immediate revision. A possible explanation for the favorable risk–benefit ratio of immediate revision is the existence of a window of opportunity for earlier revision. However, quick decision-making is crucial. Further analysis of the revision procedures revealed no new cases of intubation, only a few instances of antibiotic administration, and a very short operative time. In most cases, only the femoral head was replaced. Revision joint arthroplasty implant costs accounted for more than 50% of the total hospital costs, as compared with 43% for primary procedures. The total hospital costs for revision cases increased by 161% [19]. The length of stay for immediately revised THA was similar to that of primary THA in our series [30].

Making a decision for immediate revision is challenging and sometimes subjective. The decision should consider several procedure-related parameters, such as the type and severity of the anomaly, the patient’s contralateral side to be operated on in the short or medium term to correct the LLD, the patient’s comorbidity, and the tolerance of the first procedure. Additionally, environmental factors, such as operative time, additional operative time, late end of the procedure, available teams, and operating rooms should also be considered. While the event is rare, the psychological impact on the surgeon and their team is significant, and the indications for immediate revision are not codified. It is essential to note that immediate revision does not increase the infection rate and can help surgeons make informed decisions.

The study had some limitations. First, it was a retrospective study, although the data were collected prospectively. However, as no patients were lost to follow-up in the immediate revision group, the retrospective model did not affect the results. Second, the results may not be reproducible because all surgeons were highly experienced in an institution where a team performs > 1400 THAs per year. Third, although the sample size was small, the number of subjects exceeded the required amount, a 2 year minimum follow-up period was completed, and there were no lost-to-follow-up cases to report. Fourth, the acknowledged risk factors for PJI, such as intraoperative blood loss, previous use of immunosuppressants, and preoperative hypoproteinemia were not examined [31]. Finally, the major limitation was the timing of postoperative radiography. In our institution, a dedicated team performs radiography in the operating room, and surgeons can view the radiographs before the patient leaves the recovery room. However, in several institutions, postoperative radiography is performed at a later onset, sometimes the day after surgery, making immediate revision impossible. Although clinically suspected, only the radiograph can confirm and explain a postoperative LLD (implant positioning, size, and comparison with preoperative templating).

The study has several strengths, including its design and observation of a well-defined population (patients with primary THA undergoing immediate revision). The minimum follow-up period was 2 years, ensuring that the infection rate was not underestimated. To our knowledge, this is one of the few studies that account for the immediate revision of imperfections after primary THA. In a well-trained center with experienced joint surgeons, immediate revision appears to be a safe option when imperfections, such as LLD or instability, are identified during postoperative bed transfer or on the immediate postoperative radiograph. Although studies have shown that early revision before 12 months significantly increases infection rates, immediate revisions do not appear to be associated with this burden. Immediate same-day revision is only an extension of the initial surgery.