Introduction

High tibial osteotomy (HTO) is a valid surgical technique to treat medial degenerative osteoarthritis (OA) with varus malalignment by shifting the load to the lateral compartment through slight overcorrection [1, 3, 4, 17]. It is an effective and joint preserving procedure, especially in the young and active patient with mild unicompartmental OA [8, 18, 21, 25]. Plenty of studies show good long-term survival and clinical outcomes following HTO, as for example pain relief, return to work and sporting activities. [5, 15, 16, 19, 20, 22]. Patients’ satisfaction with surgery is rating between 77 and 98% [16]. It is known that the postoperative satisfaction is influenced by preoperative expectations and that, furthermore, unrealistic expectations of therapy can lead to dissatisfaction [2, 12, 13]. A recent study shows that patients’ expectations of osteotomies around the knee are high in terms of capacity to work, restoring functions and the relief of pain, and the progression of osteoarthritis as well as the potential need for conversion to a total knee arthroplasty (TKA) was underestimated [6]. This highlights the need for an optimal preoperative interaction between patient and surgeon to form realistic expectations for a satisfying outcome [13]. For ACL reconstruction, there is evidence that patients’ and surgeons’ expectations do not differ, and that the actual outcome shows no difference to both patients’ and surgeons’ expectations [26]. To our knowledge, there is no evidence about surgeons’ expectations on osteotomies around the knee so far.

The aim of this study was to investigate the expectations of orthopaedic and trauma surgeons of HTO. Furthermore, the postoperative treatment and the recommendations in terms of returning to sports were investigated and all results were compared to the literature. We assumed that there would be no difference between the surgeons’ expectations of HTO on the one hand and the patients’ expectations of osteotomy around the knee, as well as the outcome of HTO reported in the literature, on the other hand. Furthermore, we hypothezised that less experienced HTO surgeons would have different expectations than surgeons performing more HTOs.

Materials and methods

Study sample

A total of 461 surgeons, all members of the German speaking society for arthroscopy and joint surgery (AGA), completed an online questionnaire regarding their demographic data, their expertise and expectations concerning HTO. Most of the population was at least a specialist, 46% were proving a work experience of more than 15 years. The average age was 48.1 ± 8.6 years. 53.5% carried out up to 10 or no osteotomies at all per year (see Table 1, Figs. 1 and 2). Based on the lower experience of more than half of the study sample, two subgroups were formed [≤ 10 osteotomies/year = less experienced surgeons (n = 247) and > 10 osteotomies/year = higher experienced surgeons (n = 215)] to investigate differences concerning surgeons’ expectations depending on their experiences with HTO.

Table 1 Demographic data of the study population (age [years], gender ([% (n)], position ([%(n)])
Full size table
Fig. 1
figure 1

Demographic data of the study population (number of osteotomies around the knee [n] performed per year [%])

Full size image
Fig. 2
figure 2

Demographic data of the study population (amount of work [%] /experience [years])

Full size image

Survey of surgeons’ expectations

Surgeons’ expectations were rated using the twenty-item ‘Hospital for Special Surgery Knee Surgery Expectations Survey (HFSS-KSES)’. This represents a valid and reliable instrument that was developed patient-derived, especially for surgeries around the knee. Items are rated on a five-point Likert scale (1 = very important, 5 = this does not apply to me) and it requires less than 5 min to complete [11] (compare Table 2).

Table 2 Surgeons’ priorities of expectations of high tibial osteotomy (HTO) according to the Hospital for Special Surgery Knee Surgery Expectations Survey (HFSS-KSES)
Full size table

Additionally, a ten-item non-validated questionnaire was used to specifically investigate expectations of HTO. This questionnaire was slightly modified from a previous patients’ expectations study [6]. It refers to expectations on returning to work after surgery (distinguishing between office and physical work) (1–3), returning to sports or recreational activities (4), expected residual pain (5) and differences between the operated and a healthy knee joint (6), delay/prevention of a TKA (7) and questions on the expected plate disturbances in daily life, the aiming for plate removal as well as the question if the removal will lead to further improvement in knee function (8–10) (see Table 3).

Table 3 Non-validated ten-item questionnaire of surgeons’ expectations of high tibial osteotomy (HTO)
Full size table

To assess the postoperative treatment, a non-validated, eight-item questionnaire was conducted, referring to time and range of restriction of range of motion (ROM), time of recommended partial weightbearing and recommendations considering the return to sports (Table 4).

Table 4 Non-validated questionnaire about surgeons’ postoperative recommendations after high tibial osteotomy (HTO)
Full size table

Statistical analysis

Statistical analysis was performed using IBM SPSS Statistics for Windows (Version 27.0). Descriptive analysis of the data was performed by determining the percentages and if adequate, the mean of data. For the subgroup analysis, we performed a Mann–Whitney U test for the ordinal scaled items and an independent t test for the metric items to investigate differences. Before performing the t test, normal distribution was proven by using the Kolmogorov–Smirnov test. Significant difference was set for p ≤ 0.05.

Results

Surgeons’ ratings of the aimed outcomes of osteotomy around the knee (HFSS-KSES)

In general, surgeons’ expectations of HTO were rated between very and a little important (see Table 2). The reduction of pain was the most important item on the HFSS-KSES score being rated with 1.17. Other items showing high importance were ‘improving the ability to walk, to perform daily activities as well as having confidence in the knee, returning to work and avoiding future degeneration’. Participating in sports was rated less important (see Table 2).

Surgeons’ expectations on osteotomy around the knee

Regarding the pain reduction, only 2.2% of the questioned surgeons expected that patients would have no pain postoperative, regardless the performed activity. 35.8% expected occasional pain in demanding sports activities with contact/jumping aspects and 50.8% in less demanding sports activities. 11.3% expected their patients to have occasional pain in light physical activities or daily routine in house and garden (see Table 3).

Considering the return to work, more than 90% expected their patients to return to work on the same level without or with small limitations if having an office employment. For physical work, almost 90% expected to return on the same level with small limitations or to return to work on a slightly lower level (see Table 3). The expected average time for returning to work was 6.3 ± 2.7 weeks for office work, 10.8 ± 3.8 weeks for light/moderate physical work, 16.7 ± 6.2 weeks for heavy and 21.2 ± 5.2 weeks for heaviest physical work.

For daily activities, surgeons expected mainly slight or moderate disturbances (92.2%). Concerning the delay of knee prothesis, 95.8% expected to a delay of minimum 6–9 years (see Table 3). Regarding level of sporting activity, only 5% of the questioned surgeons expected patients to have no limitations when returning to sporting activity. They mainly expected their patients to return on to the same level as with an uninjured knee with small limitations (34.3%) or on a slightly lower level (49.7%), 11.1% expected their patients to return to a lower level.

Surgeons’ expectations depending on their experience

The ratings of the HFSS-KSES showed some significant differences between less and higher experienced surgeons. The items ‘increase knee mobility’ (p = 0.006), ‘improve ability to go up and down stairs’(p = 0.047) and ‘improve ability to squat’(p = 0.005) were rated more important of the less experienced surgeons than of the higher experienced surgeons’ (compare Table 2). The highest rated items ‘pain reduction’ (p = 0.635), ‘improvement of ability to walk’ (p = 0.130), ‘have confidence in the knee’ (p = 0.880), ‘perform daily activities’ (p = 0.065) and ‘restoring working capacity’ (p = 0.733) did not show any differences between the two subgroups.

For the surgeons’ expectations, a significant difference could be shown between less- and higher experienced surgeons’ expectations concerning the delay/prevention of a TKA (p = 0.005). Less experienced surgeons were more reluctant. Detailed information is presented in Table 3. Other significant differences appeared concerning the osteosynthesis material. Less experienced surgeons expected the material to be less disturbing (p = 0.000) while higher experienced surgeons expected patients to want the plate removed (p < 0.001), and the removal to further improve the knee function (p = 0.018). Results are presented in Table 3.

Postoperative treatment and recommendations

Concerning the postoperative treatment, 80% of the surgeons do not set restrictions on the range of motion (ROM), but recommend partial weight bearing for up to 6 weeks postoperative (52%). Almost 90% of the surgeons give recommendations on the return to sports, 59.2% considering both radiographic results and functional results, the rest considering either one. Almost 70% do not recommend knee-demanding sports like basketball, soccer, American football, rugby, handball, ice hockey, boxing after rehabilitation one year postoperative. For detailed information, compare Table 4.

Discussion

All in all surgeons’ expectations of HTO are high, the most important item being relief of pain. Further important are functional aspects like the improvement of ability to walk, having confidence in the knee, performing daily activities and restoring working capacity. For those items, there were no significant differences between the ratings of less experienced and higher experienced surgeons. For surgeons’ expectations, the most relevant significant difference regarding the experience appeared for the item ‘delay/prevention of a TKA’. The expectations of returning to work and sports, as well on pain relief and knee function did not differ between less experienced and higher experienced surgeons.

Relief of pain was already mentioned in early literature as a main indication for HTO [4]. In the present study, it indicates to be of highest importance for surgeons, and there is evidence in the literature that it is also of highest importance for patients. The former mentioned study of Grünwald et al. on patients’ expectations enrolled a total of 264 patients using the HFSS-KSES, and a similar 10-item non-validated questionnaire about expectations of osteotomies around the knee as we did in the present study. Relief of pain was rated in the HFSS-KSES by patients with a mean of 1.23 compared to 1.17 by the surgeons in the present study [6]. The results of the non-validated questionnaire on expectations of HTO show that surgeons expect more residual pain in less demanding sports (50.8%) than patients did in the former study (33%), and that patients expected more absence of pain independent of the activity d (23%) than surgeons did (2.2%) [6]. There is evidence in the literature that pain can be successfully reduced [1, 5, 7, 16, 19]. However, all of the mentioned studies asked for pain in general, using the visual analogue scale (VAS) [1, 5, 7, 19], instead of asking for activity-related pain. Pain reduction is important for both surgeons and patients regardless of the surgeons’ experience of HTO. Nevertheless, the actual expectations show a deviation where further investigations are necessary to find out about the activity-related degree of pain relief to have good evidence for preoperative preparation of patients.

As mentioned earlier, osteotomy around the knee is a treatment recommended for young and active patients [9, 18, 21, 24]. Corresponding, there is a high patients’ expectation for returning to work and sports [6]. Returning to work was rated important by surgeons in the present study as well, showing no difference between less experienced and higher experienced surgeons. Current literature gives evidence for a return to work rate to the same level of at least 90% [5, 19, 23], even for physical work. These findings are matching patients’ expectations, where 67% expected a return to work on the same level without limitations [6]. In the current study, surgeons were a bit more reluctant for returning to physical work. While 60% expected their patients to return to their physical work, only 9.5% expected so without limitations. Schröter et al. found a relation between incapacity to work and work load ranging from a median of 42 days for office work to 120 days for moderate and most heavy work [23]. This matches with the expectations in the present study expecting 6 weeks of working incapacity for office work and 21 weeks for most heavy work. Data from Faschingbauer et al. also support these findings, though by using another work-intensity classification (12 weeks for office or light physical work, 20 weeks for heavy and most heavy work).

Returning to sports was rated less important by surgeons in the present studies than it was in the patients’ expectations studies [6], again showing no difference between less and higher experienced surgeons. Having a closer look, most surgeons expected their patients to return to the same level with limitations (34.3%) or even on a lower sports level (49.7%) while more patients expected to return on the same level without limitations (23%) [6]. 87.4% of the surgeons reported to give recommendations concerning postoperative return to sport, almost 70% did not recommend knee-demanding sports. Comparing the expectations with the reported evidence in literature, the ‘return to sports rate’ is indeed more than 85% in young and active populations [5, 20, 22]. A reported shift from high- to low-impact sports [5] supports the surgeons’ expectations. Salzmann et al. [20], however, made a difference between lifetime, pre- and postoperative sports and reported a decrease of high-impact sports from lifetime to pre- and postoperative, but not between pre- and postoperative. On top of that, there is evidence about a significant impact of motivation on the return to strenuous sports postoperative [2, 22]. A preoperative individual assessment of the patients’ requirement, as for example physical aspects and motivation, is necessary to give a realistic recommendation on returning to sports.

The progress of OA and potential need for conversion to total knee arthroplasty (TKA) is underestimated by patients undergoing an osteotomy around the knee [6]. A total prevention of TKA was only expected by 3% of the surgeons in the present study while 32% of patients expected so in the former study [6]. In general, despite the relatively low evidence presented in literature, HTO seems to be a good option for delaying arthroplasty for more than 15 years in the majority of patients, the 5-, 10-, 15- and 20-year survival rates, mainly defined as no conversation to TKA over time, ranging from 86–100%, 64–97.6%, 44–93.2% and 46–85.1% [16]. While population-based studies identified a 10-year survival rate of 70–73% [15, 25], single surgeon or hospital-bound studies indicate better survival times: 94% at 5 years, 79.9% at 10 years and 65.5% at 15 years, respectively [7] and 95% at 5 years, 79% at 10 years and 56% at 15 years for patients with a potential risk factor OA Grade IV [9]. Other studies showing even better results (after 5-, 10-, 15- and 20 years 98%, 92%, 82% and 79%) have to be seen critically because of high dropout rates [1] and a comparatively young (45.8 ± 9.5 years) and small population (31 knees) [10], while higher age has been identified as a potential risk factor concerning survival time [7, 9]. All in all, HTO shows sufficient long-term outcomes, but with the longest follow-up being 20 years [1], no statements about lifetime-survival can be made. Nevertheless, the high expectations of patients and surgeons concerning delay/prevention of TKA compared to the outcome presented in the literature should be an indication to put more focus on this topic when deciding for HTO. Another important finding was the significant difference regarding the surgeons’ experience concerning their expectation for delay/prevention of TKA. Our findings indicate higher expectations of more experienced surgeons. Further studies should investigate if the experience of the surgeon influences the long-term outcome of HTO.

There is evidence that the osteosynthesis material can cause local irritations and that plate removal may cause a significant further improvement in function [14]. In the present study, higher experienced surgeons expected more irritations because of the plate and a further functional improvement after plate removal than less experienced surgeons. These findings suggest that higher experience might lead to a more realistic evaluation concerning complications, or even a better knowledge of evidence given in literature.

The literature shows high patients’ expectations regarding capacity to work, pain relief and restoring knee function when undergoing osteotomy around the knee [6]. In the present study, we found that surgeons’ expectations of HTO are also high, but deviate to the patients’ expectations found in the former study. While both surgeons and patients find the aspects ‘pain relief’, ‘improvement of ability to walk’, ‘have confidence in the knee’ and ‘restoring working capacity’ important, patients rated the aspects ‘avoiding future degeneration’ and ‘exercising’ more important than surgeons. Also, the expectations regarding the return to sports, prevention of TKA and pain relief differed in some points, surgeons being more reluctant than patients. A main difference regarding the experience of surgeons appeared for the expectation on ‘delay/prevention of TKA’ while other relevant aspects did not show any differences between the two groups.

This study has several limitations. Comparing surgeons’ expectations and patients’ expectations was only possible by comparing two different studies which were based on the same questionnaires but conducted from different populations. Outcome was also investigated from the existing literature. Also, surgeons made a general assessment regarding their expectations of HTO. However, outcome is influenced by several individual factors, which makes it hard to formulate general expectations and might lead to the more reluctant expectations in the present study.

A limitation and strength at the same time is the large population and the diversity of questioned surgeons. The large part of less experienced surgeons (10 or less HTOs per year) can represent a limitation, but by performing a subgroup analysis to investigate potential differences between less and higher experienced surgeons it rather can be rated as a strength.

To get more evident results, further investigations are necessary. A study covering both surgeons’ and patients’ expectations from the same population and including a follow-up concerning the outcome and the satisfaction of both patients and surgeons would be a possible further approach.

Conclusion

Surgeons’ expectations of HTO are high but nevertheless different to the patients’ expectations reported in the literature. Also, expectations for the delay/prevention of TKA differed regarding the experience of surgeons; therefore, both our hypotheses cannot be proven completely.

Pain reduction represents one of the most important items for surgeons and patients. The expected outcome regarding the delay/prevention of a TKA and returning to sports differs to the patients’ expectations and to the actual outcome reported in the literature. This should be considered when performing the preoperative informed consent.