Periacetabular Osteotomy Often Results in Inpatient Stay: A Tertiary Referral Institution’s Experience Supporting This Common Postoperative Course

Abstract

Background:

Periacetabular osteotomy (PAO) is a complex procedure historically requiring inpatient stay. However, there is increased emphasis for other complex orthopaedic procedures (eg, arthroplasty) to be performed on an outpatient basis by insurance companies. Increasing resistance to insurance approval of inpatient listing for PAO patients at the participating institution suggests that this changing tide is affecting PAO surgery.

Purpose:

To (1) investigate the proportion of PAOs various surgical listing classifications (outpatient, outpatient-overnight, inpatient, etc), (2) determine the incidence of subsequent denial/request for additional documentation for approval of inpatient stay after PAO, and (3) characterize the accuracy of preoperative patient listing classification as well as mean length of stay (LOS) and incidence of successful same-day discharge after PAO at a single institution.

Study Design:

Case series; Level of evidence, 3.

Methods:

A retrospective chart review was performed to identify all PAOs, performed by 4 participating surgeons, at a single academic institution over a 2-year period. The initial listing status as an outpatient-overnight or inpatient procedure was identified. Whether a preoperative peer review was required for approval of inpatient listings as well as if additional documentation was necessary to convert outpatient-overnight listings to inpatient stays were also recorded.

Results:

A total of 140 PAOs among 117 patients were performed with 25 (17.9%) initially listed as an inpatient stay and 115 (82.1%) listed as outpatient-overnight. Of the 25 PAOs listed as inpatient, 2 (8.0%) required a preoperative peer review process to justify or clarify listing status. The mean LOS was 1.9 ± 1.4 days with 55.7% (78/140) of PAOs staying ≥2 nights in the hospital. Only 6 PAOs (4.3%) went home the same day as surgery. Patients who underwent PAO with concomitant hip arthroscopy stayed on average 2.4 ± 1.2 days in comparison with 1.6 ± 1.4 days for those who underwent PAO alone (P < .001). Of the 115 PAOs listed as an outpatient-overnight, 53 (46.1%) converted to an inpatient stay, all of which required service documentation to support conversion to inpatient status.

Conclusion:

Over half of PAOs performed resulted in an inpatient stay with patients spending ≥2 nights in the hospital. Additionally, all conversions from outpatient-overnight to inpatient required additional service documentation to support status conversion. Understanding trends in postoperative hospitalizations and LOS may allow for better informed partnerships between surgeons and insurance companies creating more efficient preauthorizations, billing practices, and expected patterns of patient care and discharge.

Contemporary health insurance billing practices continue to evolve. Currently, almost all elective orthopaedic surgeries require prior authorization for payment by the insurer. ¹ Typically, factors such as the appropriateness of surgery and the anticipated setting and length of stay (LOS) are critically evaluated by insurers. In a recent survey of hip and knee arthroplasty surgeons, 95% reported an increase in the rate of required surgical prior authorizations. This process can be lengthy and burdensome for care teams, with current literature reporting a mean of 15 hours of work time per week dedicated to prior authorization and a mean of 18 claims per week. Frequently, surgeons rely on administrative assistants, nurses, advanced practice providers, and even physician trainees to handle the administrative burden. In fact, up to 71% of practices employ a dedicated staff member for insurance authorizations. ¹⁰

This process for approval can sometimes result in denial for various reasons. A recent report from the U.S. Department of Health and Human Services estimates 13% of prior authorization denials may be inappropriate based on Medicare coverage rules. ⁶ In the setting of denied coverage, a peer review process can lead to successful appeal before imaging or surgery; however, it can add to an already high administrative burden. In a recent study of orthopaedic subspecialty care, 51% of denials were subsequently approved after peer review, but they could be significantly delayed in 28% of cases by up to 30 days, calling into question the efficiency of the current model for peer review. ⁷

A point of contention for surgery approval is often the classification of the setting of surgery and the anticipated LOS. Currently, elective orthopaedic surgery is most often performed on an outpatient or ambulatory basis, where discharge occurs on the same day as treatment. ¹² Less frequently, elective orthopaedic patients might require admission (eg, because of complication or extensive monitoring) to an inpatient status, which is typically defined by a stay of ≥2 midnights in the hospital by the Centers for Medicare & Medicaid Services. ³ Somewhere between is observation status, where a patient’s stay typically lasts <48 hours while the decision for admission or discharge is determined and is typically used if there was an adverse complication requiring observation or if patients are thought to be unsafe to discharge to home (ie, due to impaired mobility). This differs from instances when ambulatory surgery patients are kept for monitoring in an extended recovery setting, also known as outpatient-overnight or bedded outpatient. In these settings, the patient is housed in a hospital bed but is considered to be outpatient in terms of payment implications and generally discharged within 23 hours or before 2 midnights.

Periacetabular osteotomy (PAO) is a complex procedure that reorients the geometry of the acetabulum to optimize the biomechanics of the hip and preserve the longevity of the joint (Figure 1). ⁵ This is often performed for patients with developmental dysplasia of the hip.^8,13 The procedure entails significant patient recovery, monitoring, and care coordination. As a result, the typical postoperative LOS is 3 to 4 days with contemporary practices (eg, antifibrinolytics, postoperative analgesia, etc).^2,9 Despite this, insurers may deny approvals for inpatient stay, or require a peer review process, due to emphasis for shorter LOS to reduce costs. This has been the experience of the current authors. Care teams must then provide documentation supporting the need for inpatient stay or for peer review. Within this context, there is limited literature documenting LOS and payment approval experiences for PAO surgery. To this point, there is also no currently available literature on outpatient PAO.

Figure 1.

(A) Preoperative anteroposterior radiograph of the pelvis demonstrating developmental dysplasia of the left hip. (B) Postoperative anteroposterior radiograph of the pelvis subsequent to periacetabular osteotomy with internal fixation.

Updated data on the perioperative factors that affect LOS and ultimately surgical listing classification are vital to helping insurance companies better understand the clinical care of complex patients. This can ease the provider-payor tug of war and create more efficient billing approval practices. This is especially critical in the setting of PAO, where there is significant patient recovery, resource utilization, and care coordination that affects the cost-effectiveness of such a complex procedure. The purpose of this study was to (1) investigate the proportion of PAOs with various surgical listing classifications (outpatient, outpatient-overnight, inpatient, etc), (2) determine the incidence of subsequent denial/request for additional documentation for approval of inpatient stay after PAO, and (3) characterize the accuracy of the preoperative patient listing classification as well as mean LOS and incidence of successful same-day discharge after PAO at a single institution.

Methods

After approval from our institutional review board, a retrospective chart review was performed to identify all PAOs performed by 4 orthopaedic surgeons (R.T.T., R.J.S., E.G., M.H.) at a single academic institution from January 1, 2022, to January 31, 2024. All patients who underwent PAO during this time frame were included. The preoperative listing status of the PAO, designated by the surgeon, as an inpatient, outpatient, or outpatient-overnight procedure was identified, as it is required for listing the surgical case onto the operating room schedule. Patients were listed under Current Procedural Terminology code 27146 (osteotomy, iliac, acetabular, or innominate bone). For PAOs preoperatively listed as an inpatient stay, the need for a peer review for approval of hospital stay and surgery was recorded. Furthermore, if any additional documentation was necessary for insurance approval to convert PAOs billed as outpatient-overnight to inpatient stays were also recorded. Patients followed a standard institutional PAO protocol, including 25% weightbearing, multimodal oral pain control, generally consisting of acetaminophen, nonsteroidal anti-inflammatory medications, and oxycodone, and deep venous thrombosis prophylaxis generally in the form of 81 mg aspirin twice daily.

Patient demographics and characteristics obtained included age at surgery, sex, laterality, and insurance provider. Whether the patient underwent concomitant hip arthroscopy, the LOS, and whether the patient received a foley, epidural, or pain catheter (regional anesthesia) as well as the postoperative days they were removed were also recorded. Factors such as foley catheter or pain catheter use were up to the discretion of the surgeon and were not standardized.

Statistical Analysis

Data were extracted with continuous variables being reported as mean ± SD while categorical variables were reported as frequencies with percentages. A Mann-Whitney U test was performed to examine the difference in LOS for patients who underwent PAO with concomitant hip arthroscopy versus those who underwent PAO alone. A post hoc power analysis was performed for data comparisons between patients with and without concomitant hip arthroscopy using G*Power Version 3.1 (Heinrich-Heine-Universtät Düsseldorf), ⁴ which demonstrated an achieved power of 0.803 for detecting a statistical difference with an effect size of 0.5 when using a Mann-Whitney U test. A P value <.05 was considered statistically significant.

Results

A total of 140 PAOs among 117 patients were performed during the 2-year time frame. The mean age at surgery was 22.7 ± 8.2 years with 90.0% (126/140) of the PAOs being completed in female patients and 52.9% (74/140) occurring in the right hip (Table 1). In total, 25 (17.9%) were preoperatively listed as an inpatient stay and 115 (82.1%) listed as outpatient-overnight (Figure 2). Of the 25 PAOs listed as inpatient at the time of listing, 2 (8.0%) required an insurance company−initiated preoperative peer review process to justify or clarify listing status. All outpatient-overnight surgical listings did not result in preoperative peer review. Similarly, there were no denials for any outpatient-overnight listings.

Table 1

Demographics and Care Details of PAOs Analyzed (N = 140 PAOs) ^a

Age at surgery, y	22.7 ± 8.2
Male	10.0
Female	90.0
Left hip	47.1
Right hip	52.9
Concomitant hip arthroscopy	40.0
Foley catheter	100
Lumbar plexus pain catheter	9.3
Epidural	0.7
Length of stay, d	1.9 ± 1.4

a

Data are presented as mean ± SD or percentage. Age, procedural details (i.e. concomittant hip arthroscopy, catheter use) are provide on a per case (PAO) basis.

Figure 2.

Percentage of cases listed as inpatient and outpatient-overnight as well as the percentage of inpatient listings that required a peer review for approval and the percentage of outpatient-overnight listings that were converted to inpatient stays.

Of all PAOs, 40% (56/140) underwent concomitant hip arthroscopy. The mean LOS for these patients was 2.4 ± 1.2 days in comparison with 1.6 ± 1.4 days for those who underwent PAO alone (P < .001). Of note, for the 23 patients undergoing bilateral PAO during the study, mean LOS was 1.8 days for the first PAO and 1.4 days for the second PAO (P = .16). All PAO cases received a foley catheter, with 90.8% (128/140) having the foley catheter removed at postoperative day 0. Thirteen PAOs (9.3%) received a lumbar plexus pain catheter, with most (11/13; 84.6%) being removed on postoperative day 2 (Table 1). Only 1 PAO of the 140 total (0.7%) received an epidural, which was removed on postoperative day 1.

After PAO, the mean LOS was 1.9 ± 1.4 days (range, 0-11 days) with 55.7% (78/140) of PAOs requiring a postoperative episode of care that qualified for inpatient stay based on institutional billing practices. Of the 115 PAOs initially listed as outpatient-overnight, 53 (46.1%) were converted to an inpatient stay, all of which required service documentation to support conversion to inpatient status. Of note, only 6 PAOs (4.3%) went home the same day as surgery.

Across all patients, a total of 24 different insurance providers were used, with Blue Cross Blue Shield being the most common (65/140; 46.4%). The insurance provider Security Health Plan required a preoperative peer review for approval of 2 of the PAO patients that were listed as inpatient (Table 2). One patient did not have insurance and paid for the procedure out of pocket.

Table 2

Top 10 Insurance Providers of Patients Who Underwent PAO

Insurance	Percentage of Patients
Blue Cross Blue Shield	46.4
Medica Mayo employee	9.3
HealthPartners	5.7
Medica	5.7
United Healthcare	5.0
Sanford Health Plan	2.8
Security Health Plan	2.8 a
Avera Health Plans	2.1
TRICARE	2.1
UCare	2.1

a

Required peer review for 2 patients with PAO billed as inpatient.

Discussion

The current study set out to investigate the proportion of PAOs with various surgical listing classifications (inpatient, outpatient, outpatient-overnight, etc), the incidence of subsequent denial/request for additional documentation for approval of inpatient stay after PAO, and the characterization of the mean LOS and incidence of successful same-day discharge after PAO at a single institution. Notably, of the 140 PAOs performed during the 2-year study period, only 17.9% were classified for inpatient stay at the time of listing. Of these inpatient listings, 8.0% required a peer review process for prior authorization of inpatient status before proceeding with surgery. Meanwhile, a majority were classified as outpatient-overnight (82.1%). Interestingly, 46.1% of the outpatient-overnight designations were converted to inpatient, and all of them required additional paperwork (additional documentation, barriers preventing discharge, etc) to be submitted to insurance to justify conversion to inpatient status. These findings put into perspective the clinical setting that most of these patients needed to recover from after PAO. Even with significant advances in the care of PAO patients in recent years, only 6% of PAOs were performed on a true outpatient basis, with 94% of PAO patients requiring, at minimum, an overnight stay and 56% needing more than a 1-night stay. Current billing and insurance practices should better reflect this reality.

A closer look at the LOS after PAO in this study demonstrates a mean of 1.9 ± 1.4 days. This is less than previously described, with typically reported ranges around 3 to 10 days.^2,9 Despite substantial advances such as improved anesthesia (ie, spinal anesthesia), local analgesic injections at the time of surgery, and availability same day physical therapy to decrease this number, only 4.3% (n = 6) of PAO patients went home the same day in this study. Many of these instances were young, healthy patients <20 years of age (n = 4). An outpatient discharge is ambitious with current techniques/technology and would be considered an outlier in the usual postoperative protocol. In fact, there is no study to date, to the authors’ knowledge, documenting cost, outcomes, and associated complications for patients discharging the same day after a PAO. However, it is important to note that with continued advances in perioperative management, as has been previously seen with total hip and knee arthroplasty, more PAOs may be able to be performed as outpatient procedures.

A significant portion of the included PAO procedures also underwent concomitant hip arthroscopy (40.0%). While this is a substantial procedure in its own right, hip arthroscopy alone does not typically necessitate an inpatient or observation admission. Certainly, the PAO portion of a combined hip arthroscopy and PAO procedure is the main driver of postoperative admission and monitoring. It is important to note that patients who underwent PAO with concomitant hip arthroscopy stayed on average 0.8 days longer than those who underwent PAO alone, suggesting these patients may take longer to clear discharge criteria. It is a notable fact that 40% of the PAO surgeries performed in the current study were combined with hip arthroscopy. This allows for the observed results to be applied to patients undergoing PAO in isolation, or as a part of a combined arthroscopic/open procedure, further increasing the applicability of this study to other practices.

Even though a large proportion (46.1%) of outpatient-overnight patients subsequently underwent conversion to inpatient classification, we continue to generally list PAO patients with an outpatient-overnight designation. This facilitates a compromise between resource preparation and a pragmatic anticipation of extended monitoring with at least a projected overnight stay, and the ability to convert to inpatient if further monitoring and hospital services are needed. Yet certain patients may have substantial comorbidities or other medical factors (ie, cerebral palsy, cardiac history) that may effectively preclude the possibility of an outpatient-overnight PAO. These patients are better suited for inpatient listing for more appropriate preoperative care coordination, assurance of bed availability, and reasonable expectation setting and discharge planning.

Of note, 8% of patients listed as inpatient required a peer review process during preoperative approval process in this study. Yet, the majority of patients in this study stayed ≥2 days in the hospital after PAO. This highlights a disconnect between the most common postoperative course for these patients and the projected/predicted outcome by insurers. While no patient listed initially as outpatient-overnight prompted a peer review for listing status, listing patients in such a manner does not necessarily reflect the clinical reality of the majority of PAO surgeries and may furthermore circumnavigate appropriate resource planning (ie, bed availability).

A study by Rodriguez et al ¹¹ compared whether insurance company determinations of outpatient status are as reliable as surgeon-derived criteria in predicting outpatient discharge after a total knee arthroplasty. They found that surgeons correctly predicted outpatient discharge 92.0% of the time in comparison with 81.3% of the time for insurance companies (P < .001). Additionally, total knee arthroplasty predicted to be outpatient by insurance companies were twice as likely to be converted to inpatient in comparison with surgeons’ predictions. These findings are not surprising and are likely able to be extrapolated to the majority of surgical scenarios. Given the face-to-face interaction between a patient and his or her surgeon in the clinic, a patient’s needs (family assistance, preoperative functional status, etc) can be better assessed by the surgeon as the surgeon has better access to the patient and can be more accurate when predicting the anticipated LOS. In the setting of PAOs performed in this study, over half of them were initially listed as, or ultimately transitioned to, an inpatient stay. These data could help better inform mutually beneficial communication and planning between health care teams and insurance companies.

Limitations

The present study is not without limitations. Our institution serves as a tertiary referral center, with PAOs being performed by high-volume surgeons with substantial technical expertise in the treatment of hip dysplasia. Thus, it is likely that experienced surgeons played a vital role in the observed LOS compared with published LOS in previous literature.^2,9 Furthermore, the efficiency of postoperative recovery and discharge is dependent on high-functioning interdisciplinary teams. Thus, not all centers performing these procedures have equal access to this, which affects the generalizability of these data to lower-volume centers. Additionally, reasons determining LOS in PAO patients are multifactorial and often include pain management, difficulty with safe ambulation and associated clearance to home care, and postoperative return of bowel and bladder function, with admission and overnight stay often resulting from a combination thereof. As such, it is not possible to retrospectively define the determinants of each patient’s LOS. Our results are susceptible to the biases inherent to retrospective reviews such as incomplete recordkeeping and lack of comparison groups. As such, there may be confounding variables contributing to the initiation of peer reviews outside of predicted LOS, not accounted for by this study. Last, this study did not aim to collect and analyze data regarding complications and readmissions after PAO surgery and represents a topic of interest for future prospective studies.

Conclusion

Over half of PAOs performed required inpatient stay beyond outpatient-overnight status. Additionally, all conversions from outpatient-overnight to inpatient required additional service documentation to support status conversion. Understanding trends in postoperative hospitalizations and LOS may allow for better informed partnerships between surgeons and insurance companies in creating more efficient preauthorizations, billing practices, and expected patterns of patient care and discharge.