Abstract
Background Anterior lumbar interbody fusion (ALIF) is a well-established procedure for the treatment of spondylosis, spondylolisthesis, and degenerative disc disease but can cause sexual dysfunction and retrograde ejaculation (RE).
Objective We assessed the occurrence of sexual dysfunction and RE and explored associations between patient and surgical characteristics with sexual dysfunction, RE, and patient satisfaction with the outcome of surgery.
Methods This is a retrospective survey study. A short questionnaire on changes in sexual function, RE, and patient satisfaction was sent to 170 male patients aged 18 to 60 years who underwent a primary ALIF at L5/S1, L4/L5, or both via retroperitoneal approach between 2015 and 2020 in a high-volume spine centre in Switzerland. Factors associated with changes in sexual function and with RE were examined in univariable and multivariable logistic regressions. The multivariable logistic regression model was adjusted for age at surgery, time since surgery, level of surgery, and fusion material. The associations between satisfaction with the outcome of surgery and time since surgery and changes in sexual function were also assessed using univariable logistic regression.
Results Of the 170 patients contacted, 98 (58%) agreed to participate. The most frequent fusion level was L5/S1 (n = 74, 76% of respondents), and InductOs was generally used (n = 69, 70%). Overall, 21 patients (21%) reported changes in sexual function, and 11 (11%) felt signs of RE. The majority of patients were satisfied with the surgical outcome (n = 83, 85%) and would undergo the surgery again (n = 83, 85%). In all regression models, changes in sexual function and RE were not associated with any of the studied factors. The odds of being satisfied with the surgery were 4× higher for patients who did not observe changes in sexual function than those who did (95% CI, 1.24–12.86).
Conclusions The risk of sexual dysfunction and RE after ALIF is relevant, and patients need to be adequately informed about these complications, especially if they want to have children. At the same time, the ALIF procedure remains a successful treatment option with high patient satisfaction.
Clinical Relevance The study emphasizes the need to provide patients with adequate information regarding ALIF surgery.
Level of Evidence 4.
Introduction
Spinal fusion is a valuable surgical procedure for a variety of spinal pathologies, and there are several surgical approaches to achieve solid bone fusion. One of the most effective procedures is anterior lumbar interbody fusion (ALIF),1 which is recommended for the treatment of spondylosis, spondylolisthesis, and degenerative disc disease, among others.2
ALIF has several advantages compared with the lateral and posterior techniques. The anterior approach to the lumbosacral spine allows surgeons to expand the disc space and to regain anatomic alignment without injuring the posterior paravertebral muscles. Furthermore, the anterior approach preserves all posterior stabilizing structures and avoids epidural scarring and perineural fibrosis. However, the anterior approach also has some disadvantages, such as the risk of damage to abdominal viscera, ureters, and great vessels.3 In men, the surgical exposure of the hypogastric plexus, which lies in front of the fifth vertebra and the sacrum, medial to the internal iliac arteries, bears the risk of injury of small nerve fibers. The result is impaired innervation and dysfunctional contraction of the internal bladder sphincter, which closes the bladder during ejaculation and forces semen to exit through the urethra. Retrograde ejaculation (RE), which prevents proper ejaculation of semen, can be the result of this dysfunction. RE can present in different degrees, ranging from a reduction in ejaculated sperm to complete absence.4 The incidence of RE after ALIF varies widely in the literature. The most recent systematic review describes an overall incidence of RE of 2.3%.5
RE is associated with reduced fertility and is clearly undesirable in men who want to have children. Therefore, some surgeons avoid using an anterior approach in men of reproductive age.6 To assess the quality of care for future improvement in a high-volume spine centre in Bern, Switzerland, we aimed to survey the prevalence of RE in male patients who underwent ALIF and to analyze potential predictors associated with sexual dysfunction as well as patients’ satisfaction with the surgical outcome. Furthermore, we aimed to investigate whether there was a relationship between these two variables.
Methods
Study Design and Patients
This was a retrospective study in a high-volume spine centre in Bern, Switzerland, that performed 1561 spine surgeries in 2022 and approximately 120 to 130 ALIF surgeries per year between 2014 and 2021. We included male patients aged 18 to 60 years who underwent a primary ALIF L5/S1, L4/L5, or L5/S1 + L4/L5 (stand alone or in combination with posterior instrumentation) between January 2015 and December 2020. All of the surgeries, including the surgical approach, were performed by three experienced senior spine surgeons according to a well-established operation technique. In both groups, disc space was approached through a mini-open laparotomy via a left retroperitoneal approach followed by a complete discectomy and endplate preparation. After distraction of the disc space, a cage adapted in dimensions to the individual physiological requirements was press-fit inserted into the intervertebral disc space and fixed with screws into the adjacent cranial and caudal vertebrae according to the manufacturer’s guidelines. The implant dimensions, lordosis, and height were adapted to the estimated individual physiological size and angle of the intervertebral space. To achieve intervertebral fusion, the implanted cage was filled with a fusion material. We excluded patients with previous surgeries with an anterior or anterolateral approach.
The local ethics committee waived the requirement for approval of the study becasue it did not fall within the scope of the Human Research Act, Art. 2 (BASEC-Nr: Req-2021–00908).
Data Collection
We developed a questionnaire with the following 4 questions, which were available in German and French:
Have you noticed any changes in your sexual function after surgery? (yes, no, or unsure)
Have you noticed a decreased amount or absence of ejaculation? (yes, no, or unknown)
How satisfied are you with the outcome of the surgery? (Not at all satisfied [1] to very satisfied [10])
Would you undergo this surgery again? (yes, no, or unknown)
We extracted clinical data such as date of birth, date of the ALIF surgery, and level of the surgery from the electronic clinical information system. The time since surgery was calculated as the period between the ALIF surgery date and the survey date. The questionnaire was provided in paper form, and the data were entered into a REDCap (Research Electronic Data Capture) cloud database and stored in encrypted form. All eligible male patients received a letter of invitation to participate in the study, which included information about the study, an informed consent form, the questionnaire, and a prepaid return envelope. Nonresponders were sent another questionnaire 4 to 6 weeks later. In addition, all patients who reported changes in sexual function or were unsure of it were contacted by phone to find out what changes they had observed or why they were unsure.
Definitions
We defined changes in sexual function as any subjectively perceived change in sexual function. RE was defined as the subjective experience of less or absent ejaculation. The satisfaction of the surgical outcome was collected using a Likert-type item ranging from 1 (unsatisfied) to 10 (very satisfied). We grouped the satisfaction of the surgical outcome as follows: 1 to 3 as unsatisfied, 4 to 7 as somewhat to moderately satisfied, and 8 to 10 as satisfied to very satisfied.
Statistical Methods
We used descriptive statistics to characterize the patients by changes in sexual function and by satisfaction with the outcome of surgery.
We examined factors associated with changes in sexual function and RE in univariable and multivariable logistic regression. The multivariable logistic regression model was adjusted for age at surgery (years, continuous), time since surgery (days, continuous), level of surgery (L4/L5, L5/S1, and L4/L5 + L5/S1), and fusion material (InductOs, autologous iliac crest bone, other). In the regression analysis, we excluded patients who reported that they were unsure whether they had observed changes in sexual function or had missing data. Goodness of fit of the regression models was assessed using McFadden’s pseudo-R 2.
We also looked at whether (1) changes in sexual function and (2) the time since surgery were associated with satisfaction with the outcome of surgery (comparing satisfied and very satisfied patients vs unsatisfied and somewhat to moderately satisfied) using univariable logistic regression.
Finally, we conducted a sensitivity analysis of age among responders and nonresponders, based on the null hypothesis that there is no difference in this regard between the 2 groups.
The level of significance was 0.05. All statistical analyses were conducted using R Studio 4.2.2.
Results
Patients
We identified and contacted 170 eligible men, of whom 98 responded (response rate 58%) and were thus enrolled in the study. The median age was 44 years (interquartile range 35–52). An ALIF on L5/S1 was performed in 74 patients (76%), on L4/L5 in 6 patients (6%), and on L4/L5 + L5/S1 in 13 patients (13%). For the remaining 5 patients (5%), the surgical level could not be identified because the corresponding returned questionnaires were anonymous and, therefore, not linkable to patients’ records.
The most frequently used fusion material was InductOs (rhBMP-2; n = 69 [70%]), followed by autologous bone harvested (iliac crest bone harvesting; n = 20 [20%]) and other fusion material (n = 4 [4%]). For the 5 anonymous patients (5%), the fusion material was unknown.
Information on the time since surgery was available for 93 patients. On average, 3.8 years (median 1363 days, min 313, and max 2517 days) had passed between surgery and the survey.
Tables 1 and 2 show patient characteristics stratified by changes in sexual function (Table 1) and satisfaction with the surgery (Table 2).
Patient characteristics by changes in sexual function after anterior lumbar interbody fusion.
Patient characteristics by satisfaction with the anterior lumbar interbody fusion.
Changes in Sexual Function and Rate of Retrograde Ejaculation
Overall, 21 patients (21%) reported changes in sexual function, 72 (73%) reported no changes in sexual function, and the remaining 5 patients (5%) were unsure. Among the 21 patients with changes in sexual function, 11 (52%) reported a reduction or absence of ejaculation, 3 (15%) an erection dysfunction, 1 (5%) a sensitivity disorder in the genital area, and 1 (5%) having less sex. In the remaining 5 patients (24%), no further details could be obtained.
The predominant fusion material among patients with changes in sexual function was InductOs, which is rhBMP-2 (86% vs 64% in those without changes in sexual function). This was similar to those with RE (82%).
Both in the unadjusted and the adjusted regression models, changes in sexual function were neither associated with patient age at surgery, the time since surgery, the level of the fusion, nor with the fusion material (Table 3). The pseudo-R 2 of this model was 0.07, indicating that the model only had limited predictive ability.
Multivariable logistic regression on factors potentially associated with changes in sexual function.
Furthermore, both in the unadjusted and the adjusted regression models, RE was also not associated with patient age at surgery, the level of the fusion, fusion material, or time since surgery (Table 4). The pseudo-R 2 of this model was 0.09, indicating that the model also had limited predictive ability.
Multivariable logistic regression on factors potentially associated with retrograde ejaculation.
Satisfaction With the Outcome of Surgery
The majority of patients (n = 83, 85%) reported being satisfied to very satisfied with the surgical outcome, 12 (12%) were somewhat to moderately satisfied, and 3 (3%) were unsatisfied. Similarly, 83 patients (85%) would redo the surgery, whereas 10 (10%) would not and the remaining 5 (5%) were unsure.
Among the patients who reported changes in sexual function (n = 21), 14 (66.5%) were satisfied to very satisfied with the surgery, and 14 (66.5%) would redo the ALIF surgery. Among patients with RE, 9 of 11 (81.8%) would redo the ALIF surgery.
There was an association between patient satisfaction with the outcome of surgery and changes in sexual function, with 5 times higher odds of being satisfied with the surgical procedure for patients who did not observe changes than those who did (OR 5.00, 95% CI 1.45–17.90; P = 0.01). There was no association between the time since surgery and patient satisfaction (OR 1.00, 95% CI 0.999–1.001; P = 0.88).
The mean patient age in the responder group was 44 years (SD 11 years; CI 41–46 years; min–max 19–60 years), while the mean age in the nonresponder group was 45 years (SD 9 years; 95% CI 43–47 years; min–max 25–60 years). The mean difference in age between those groups was only 1.75 years, which was statistically not significant (P = 0.27).
Discussion
In this retrospective study of patients who underwent a primary ALIF procedure, 21% reported changes in sexual function and 11% proclaimed RE. Patient satisfaction with the surgery outcome was high, with 85% of the patients reporting that they would redo the surgery. There was a negative association between changes in sexual function and satisfaction with the surgery outcome, with a higher satisfaction in patients who did not observe changes compared with those who did.
RE is a well-known complication after anterior lumbar surgery due to the risk of hypogastric plexus injury. However, the incidence of RE reported in the literature varies greatly. A recent systematic review reported a range between 0.0% and 9.8% and calculated a pooled incidence of 2.3%.5 The RE rate of 11% observed in our study exceeds the rates reported in the studies that were included in the systematic review. On the one hand, this is surprising given that all patients in our study underwent a retroperitoneal approach, which has been reported to be associated with a 10-fold lower rate of RE than a transperitoneal approach.4 On the other hand, the rate of self-reported RE may be higher than that assessed based on objective criteria. The RE rate of 9.8% in the systematic review originated from the study by Tepper et al.7 This RE rate was diagnosed based on laboratory criteria, whereas 41.7% of patients who filled out the questionnaire in this study self-reported a decrease in ejaculate volume.7 Concurrently, the topic of sex and dysfunction or failure may be taboo and underreported in some patients, particularly if the patients are not actively and explicitly asked about it. Thus, besides the study by Tepper et al with the RE rate of 9.8%, which was diagnosed based on laboratory criteria, the systematic review by Body et al included studies that used questionnaires, queried patients directly on RE symptoms, or discussed RE as a complication as part of the informed consent, and a study in which surgeons (only) retrospectively asked other spine surgeons about their patients’ complications.5 The pooled overall incidence of RE in the review by Body et al was 2.3 %.5
Of note, the estimated natural prevalence of RE in patients attending fertility clinics ranges from 0.3% to 2%,8 which is substantial. Similarly, the prevalence of erectile dysfunction among men younger than 40 years is 1% to 9%, but between the ages of 40 and 59 years, the reported prevalence ranges from 2% to 9% to as high as 20% to 30%.9
We studied several factors that were hypothesized to be associated with sexual dysfunction and RE, namely time since surgery (as there is a recovery in almost half of patients with RE),5 age at surgery (as the prevalence of sexual dysfunction increases with age),10 and level of surgery (due to the manipulation of the autonomic plexus during an approach to the lower lumbar segments, particularly on L5/S1). None of the hypothesized and assessed factors was either associated with sexual dysfunction or with RE. The absence of an association between changes in sexual function and level of fusion is consistent with the literature.5,11
The role of rhBMP-2 as a risk factor for RE has been controversially discussed in the literature. Some studies showed an association between rhBMP-2 and rates of RE, whereas others did not.12–14 The retrospective studies by Carragee et al and Comer et al showed a higher rate of RE (7.2% in 69% and 6.9% in 239 patients, respectively) in ALIF procedures using rhBMP-2 compared with the control groups (0.6% and 0.9%, respectively).12,13 Comer et al hypothesized that this effect may be associated with an increased risk of postoperative urinary retention after BMP-2 exposure.13 Lubelski et al retrospectively studied 59 patients with and 51 patients without rhBMP-2 and observed no differences in rates of RE (8% in each group).14 An analysis that pooled data from five prospective randomized trials found that rhBMP-2 was associated with a higher incidence of RE (3.4% in 207 patients vs 1.7% in 301 patients) than other fusion materials. However, this difference did not reach statistical significance.11 In this study, rhBMP-2 was used in 86% of patients who reported changes in sexual function and in 82% of patients who reported RE vs 64% in those who reported no changes in sexual function. In neither the unadjusted nor in adjusted analysis was the fusion material associated with reported changes in sexual function or with RE. Siemonov et al, in a review article from 2014, and Malik et al, in a systematic review from 2018, emphasized the inconclusive evidence of the impact of BMP-2 usage on RE/sexual dysfunction.15,16 According to Mroz et al, there is a lack of standardized assessment for RE in the published literature, which probably causes underreported RE and a compelling need to develop such a standard assessment.17
The rates of sexual dysfunction and RE after ALIF are high and therefore require adequate and transparent patient information before surgery. This is particularly relevant for patients who wish to have children, as they may want to consider alternative surgical approaches. While ALIF maintains better sagittal alignment by restoring disc space height and lordosis, restoring foraminal height, and preserving all posterior stabilizing structures,2 it shows similar results as posterior and transformational lumbar interbody fusion regarding clinical outcomes, such as fusion rates, pain reduction, recovery rate, and quality of life.2 At the same time, patients with a desire to have children and who choose ALIF may be advised to cryopreserve sperm before surgery.
Strengths and Limitations
All patients were operated on by three experienced surgeons using the same standard surgical technique. This means a high internal validity of the underlying study. However, the transferability of the study results to other surgeons and hospitals may be limited.
Several other limitations exist. First, as a retrospective survey, our study faces the risk of recall bias. Second, patient self-reported feedback on complications has been shown to have falsely higher RE rates than those measured using objective criteria in laboratory settings.7 Third, there was a low response rate and a potential selection bias between patients who responded and those who did not, as patients without changes in sexual function and/or RE might have been less interested in responding to the questionnaire, which could have resulted in higher RE rates in our patient population. While the sensitivity analysis of age between responders and nonresponders revealed no statistically or clinically significant differences, we were unable to investigate other potential differences between these groups because such data are not routinely collected. Therefore, we cannot exclude the possibility that such differences existed. However, even assuming that all 72 nonresponders did not have RE, it would still result in a relatively high RE rate of 6%. Fourth, due to the small number of patients with an event, the quality of the multivariable model was limited, which is reflected in the relatively low value of McFadden’s pseudo-R 2. Last, due to the exploratory nature of our study, we did not collect data on mental and physical comorbidity, other surgical procedures, or the use of medications, which could also have had an effect on sexual function and the amount of ejaculate.7,10,18
Conclusions
Given the high occurrence of changes in sexual function and RE following ALIF in our patient population, adequate and transparent patient information about the risks of these conditions is required prior to ALIF surgery. This is particularly relevant and important for patients who want to have children. At the same time, the ALIF procedure remains a successful treatment option with high patient satisfaction in four out of five patients.
Acknowledgments
We thank Lukas Staub of Talus Research Consulting (talus.com.au) for the methodological support and for helping with the statistical analyses and results reporting. Moreover, we thank Loretta Scheurer and Katia Schiegg for support in data collection and Nathalie Buser for data management.
Footnotes
Funding This project was partly funded by the Wyss Foundation USA.
Declaration of Conflicting Interests T.D., E.A., Y.R., P.D., and P.F.H. have no conflict of interest. L.M.B. is consultant for icotec, Kuros, Sentryx, and a research advisor for AOSpine and Sentryx. L.M.B. reports advisory board payments from Zeiss and Kuros; participation on a data safety monitoring board/advisory board from Sentryx (compensation as study site); and leadership roles for AO Spine (expenses and per diems).
Author Contributions T.D., P.D., L.M.B., and P.F.H. designed the study. T.D. collected the data. T.D., L.K., and Y.R. drafted the manuscript. T.D., E.A., and P.F.H. interpreted the findings. E.A., Y.R., L.M.B., and P.F.H. critically reviewed the manuscript. All authors read and approved the final version of the manuscript.
- This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2025 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.
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