Is patient-specific pre-operative preparation feasible in a clinical environment? A systematic review and meta-analysis

Abstract

Technical difficulty of an operation is associated with patient and disease characteristics, indicating the necessity for surgeons to exercise patient-specific preparation. Such methods have been shown to be effective in the simulation suite, however, application in a real clinical environment has been sporadic. This systematic review attempts to answer if patient-specific preparation in challenging surgical procedures is feasible. A systematic review of OvidMedline, Embase and all Evidence Based Medicine review databases, was conducted in search of studies who described surgical rehearsals in all specialties. Following the application of defined inclusion and exclusion criteria relevant data were extracted and summarised. Descriptive synthesis was performed for all included studies and meta-analysis of data was applied when possible. Of fourty-nine studies included, thirty-seven were case-series, ten were non-randomised comparative trials and two randomised controlled trials. Accuracy of applied methods ranged from 66.7 to 100% and a good outcome was seen in 60–100% of operations. Meta-analysis of studies comparing rehearsals to real procedures (same patients) showed that simulated procedures were significantly faster than real ones (SMD = −1.56 [−2.19, −0.93] p < 0.00001) but were similar in other outcomes (fluoroscopy time: SMD = −0.1 [−0.63, 0.42] p = 0.7, fluoroscopy volume: SMD = −0.43[−0.97, 0.11], p = 0.12). Meta-analysis of studies comparing pre-operative rehearsals to standard treatment (two distinct groups of patients), demonstrated that real procedures were performed quicker if pre-operative rehearsal took place (SMD = −0.47 [−0.79, −0.16], P  = 0.003) but the immediate clinical outcome was similar for practiced and not practiced operations (SMD =0.03[−0.23, 0.29], p = 0.82). Current evidence suggests that patient-specific pre-operative preparation is feasible and safe and decreases operational time.

Keywords:

• Patient-specific
• surgical rehearsals
• simulation
• 3D imaging

Introduction

Patient and disease-specific characteristics are associated with an operation’s technical complexity [1–6]. Hence, a methodical preparation towards challenging surgical procedures, encompassing patient-specific features, may have a significant effect on improving both the quality and outcome of surgery. Emerging technologies, such as 3D image reconstruction (e.g. fusion of 2D- into 3D-images using computed tomography (CT) slides), and rapid prototyping (building a physical model using computer aided design (CAD) software, e.g. 3D printing) facilitate the effective and accurate construction of patient-specific anatomical models, surgical guides and implants [7–10], thus opening new avenues for pre-operative rehearsals.

Despite the increase in popularity within the last twenty years the feasibility, accuracy and clinical impact of patient-specific pre-operative preparations have not been well established [7, 8, 11], impeding their uptake into routine clinical practice. The primary aim of this review was to evaluate whether patient specific pre-operative preparation is feasible in the time-pressured environment of surgical specialties. Moreover, safety, accuracy and clinical impact were assessed.

Methods

This systematic review was performed according to the PRISMA guidelines [12]. A systematic review of OvidMedline (1946-July 31st 2015), Embase (1947-July 31st 2015) and all Evidence Based Medicine (EBM) review databases, including Cochrane databases, was conducted using the following terms: “patient”, “specific”, “simulat*”, “surg*”, “planning”, “patient specific” and “rehearsal”. The search strategy was validated with the identification of eight studies familiar to the authors and believed to be appropriate for inclusion. Review papers were searched by hand for additional studies appropriate for inclusion.

Inclusion criteria

Studies on patient-specific pre-operative rehearsals or planning followed by the performance of real-time operations were included in this review. The term “rehearsals” is used here to reflect physical re-enactment using virtual surgical tools (i.e. similar to the ones used in real surgery), whilst planning refers to viewing an anatomical model and deciding on a surgical strategy with or without the use of virtual tools that are dissimilar to the ones used in a real theatre. Only studies written in English were included.

Exclusion criteria

Studies reporting merely construction of anatomical models or simulators without subsequent real-time operations were excluded because the aim of the review was to assess clinical impact of the preparation process. Case reports, reviews, editorials, abstracts and conference proceedings were excluded from further analysis. Studies on peri-operative navigation without pre-operative preparation were also excluded. Also, studies exclusively on paediatric or foetal surgery were excluded.

Identification of relevant studies

Two authors independently assessed studies identified through the literature search for relevance, by reading the title and abstract. Full text was retrieved for all studies potentially meeting the eligibility criteria.

Data extraction

Data extraction from selected studies was done using a Microsoft® Excel spreadsheet, which included the following categories: authors, country, year of publication, anatomical model type, type of surgery, number of participants, rehearsal/planning process, number of cases pre-operative planning was followed in, clinical outcomes, other outcomes, cost and time requirements for preparation of pre-operative planning session. Data extraction was conducted independently by two authors and subsequently validated by a third. Descriptive synthesis was performed for all included studies, structured around the PICO (Participants, Intervention, Comparators, Outcome measure) approach [13].

Meta-analysis

For the purposes of the meta-analysis assumption of normal distribution of the data was made and the following mathematical equations were used to calculate Standard Deviation (SD) on different occasions (collaboration):

1. SD = IQR (Interquartile range) width/1.35

2. SD = √N (CI (Confidence Interval) upper limit – CI lower limit)/4.128

3. SD = SE (Standard Error)/√(1/N_E+1/N_c), SE = Mean Difference (MD)/t

N: sample size

N_E: sample size of intervention group

N_c: sample size of control group

t: ratio of difference in means to standard error of difference in means

Results

The literature search yielded 1779 records. Of these, 652 were duplicate studies and were therefore excluded. Titles and abstracts of the remaining 1127 studies were assessed for relevance, by two of the authors. Full text was acquired for 130 studies. From these, 45 matched the inclusion criteria. Manual search of references (from review studies identified during the literature search) yielded 4 additional studies for inclusion (Figure 1).

Figure 1. PRISMA flowchart.

Study characteristics and description

Studies were published between 1998 and 2015 (Table 1). Of fourty-nine studies matching the inclusion criteria, 37 were case-series, 10 were non-randomised comparative trials and 2 randomised controlled trials. The most common surgical specialities in the included studies were maxillofacial surgery (n = 16) [7, 8, 14–27] and orthopaedics (n = 15) [9, 10, 28–40] (Table 1).

Table 1. Characteristics of included studies

Author - Year – Country	Study design	Procedure	Sample size	Intervention
Perry et al. [23] – UK	CS	Orbital reconstruction	21	Virtual planning of procedures and (for selected cases) inspection of physical models
Kockro et al. [11] – Singapore	CS	Brain tumour excision and vascular malformation repair	21	Planning using a virtual reality platform
Lo et al. [22] – Taiwan	CS	Fronto-orbital defects reconstruction	4	Rehearsals using physical models created through CAM – manufacturing of synthetic implants
Leong et al. [16] - USA	CS	Excision of sino-nasal lesion	22	Preoperative virtual planning and 18/22 intraoperative navigation
van Steenberghe et al. [50] - Switzerland, Belgium, Sweden	CS	Surgery for fully endentulous maxillae	27	Planning using virtual 3D images and construction of physical surgical guides and prostheses
Radecka et al. [49] - Sweden	CS	Nephrolithotripsy	8	Rehearsals with synthetic models manufactured using CAD
Gateno et al. [20] -USA	CS	CMF deformity repair	5	Virtual planning and CAM of physical surgical splints and templates – intraoperative navigation for some cases
Xia et al. [27] – USA	CS	CMF deformity repair	5	Virtual planning and CAM of physical surgical splints and templates – intraoperative navigation for some cases
Hislop et al. [44] - US	NRC	CAS	5	Virtual operation on simulator
Lu et al. [53] - China	CS	Insertion of laminar screws	9	Virtual planning and manufacturing of navigational template through rapid prototyping
Ng et al. [47] –Singapore	CS	Cerebral AV malformation	23	Planning using a virtual reality platform (Dextroscope, Volume Interactions, Singapore)
Dhanda et al. [17] - USA	CS	TMJ replacement	4	Physical models manufactured from virtual models – design and manufacturing of implants and guides
Fornaro et al. [29] - Switzerland	CS	Acetabular fracture repair	7	Virtual surgery and virtual adaptations of implants (prebending)
Qiu et al. [43] – China	CS	Cerebral gliomas resection	45	Planning using virtual reality platform (Dextroscope, Volume Interactions,Singapore)
Dong et al. [28] – China	CS	Extremity tumour resection	5	Virtual planning
Essig et al. [18] - Germany	CS	Mandibular reconstruction	3	Planning with virtual and physical models – surgical plates pre-bent during preparation
Ferrari et al. [48] - Italy	CS	Various general surgery ops	10	Planning of cutting planes using virtual models
Hu et al. [31] - China	CS	Acetabular fracture repair	7	Virtual planning of procedure and plate contouring
Tepper et al. [7] - US	CS	CMF reconstruction	2	Virtual surgery and inspection of physical models as well as preparation of physical surgical splints and implants
Derand et al. [16] – USA, Sweden	CS	Various CMF ops	4	Virtual planning of operation – design and manufacturing of plates, mesh and cutting guides
Kanzaki et al. [54] - Japan	CS	Thoracoscopic multi-subsegmentoctomy	11	Virtual planning
Kerens et al. [33] - Netherlands	CS	TKA	10	Virtual planning – design and manufacturing of cutting guides
Nam et al. [9] - US	NRC	TKA	Group 1 37 (41 knees) – group 2 38 (41 knees)	Computer Assisted Surgery (CAS) versus pre-operative planning and construction of Patient Specific Cutting guides (PSC)
Scolozzi [25] - Switzerland	CS	MF reconstruction	2	Virtual surgical planning – design and manufacturing of PS implants
Shen et al. [37] - China	CS		6	Semi-automatic virtual surgery and construction of virtual and real implants
Willaert et al. [45] - Australia	NRC	CAS	18 (3 excluded)	Virtual operations on simulator with the participation of the entire surgical team
Adolphs et al. [14] - Germany	CS	Dentofacial reconstruction	10	Virtual surgery with two types of splints – optimal splint manufactured with rapid prototyping
Desender et al. [41] – Belgium	NRC	EVAR	10 (1 excluded)	Virtual procedures on simulator
Hsu et al. [21] – USA	NRC	Dentofacial reconstruction	65	Virtual planning and CAM of physical surgical splints and templates – intraoperative navigation for some cases
Issa et al. [32] – USA	CS	TKA	84 (89 knees)	Computer generated preoperative plan and manufacturing of PS instrumentation and cutting blocks
Mandel et al. [57] - Brazil	CS	Various NS ops	18	Virtual planning
Pietsch et al. [35] - Austria	CS	TKA	50	Computational planning of surgery and designing of PS implants
Schweizer et al. [36] - Switzerland	CS	Malunited radial fracture repairs	6	Planning of cutting planes on virtual model – design and manufacturing of drill guides
Small et al. [38] - USA	RCT		36	Virtual procedures on VRS – patient specific implants designed and manufactured
Victor and Premanathan [39] - Belgium	CS	Knee osteotomies	14	Virtual planning and manufacturing of physical guides
Ayoub et al. [15] - Germany	RCT	Mandibular reconstruction	20	Planning using virtual and physical anatomical models – design and manufacturing of cutting guides
Franceschi et al. [30] – France	NRC	TKA	107	CT introduced in planning software for design and manufacturing of physical cutting guides
Gander et al. [19] – Switzerland, Netherland	CS		12	Virtual planning – design and manufacturing of PS implants. Intraoperative navigation for 7/12
Haq et al. [8] - UK, US	CS	TMJ ankyloses surgery	5	Interactive virtual surgery and construction of real cutting guides and implants
Leeuwen et al. [34] – Norway	CS	TKA	39 (42 knees)	Virtual planning – design and manufacturing of physical guides
Makiyama et al. [46] - Japan	CS	Lap renal surgery	13	Virtual operation on simulator
Fürnstahl et al. [10] - Switzerland	CS	Osteotomies of tibia plateau malunions	3	Semi-automatic virtual surgery and construction of real surgical guides
Isotani et al. [55] – Japan, USA	CS	Partial nephrectomy	20	Virtual surgery
Kusaka et al. [56] - Japan	CS	Kidney transplant	2	Planning with virtual and physical models
Li et al. [58] – China	CS	Revision lumbar discectomy	9	Virtual planning
Li et al. [51] – China	NRC	Management of dural A/V malformation	37	Group A: Preoperative planning using 3D printed models – Group B: routine practice.
Schepers et al. [24] -	CS	Fibula reconstruction	7	Virtual planning and CAM of physical guides for introducing implants
Steinbacher et al. [26] - USA	CS	CMF ops	6	Virtual surgery – design and 3d printing of guides, splints and implants
Vlachopoulos et al. [40] - Switzerland	NRC	Forearm osteotomies	14	Virtual surgery – design and manufacturing of physical drill and cutting guides

Participants

The participants were patients due to undergo surgery. Whilst most preparation processes involved only the surgeon, in 2 studies the entire surgical team was involved aiming to achieve improved coordination [41, 42].

Type and content of intervention

The methods for patient-specific preoperative preparation included: i) surgical planning; allowing the surgeon to establish the surgical approach and dissection sequence, but not including a complete physical rehearsal of the procedure e.g. inspection of anatomy with augmented reality environment platforms [37, 43], or ii) surgical rehearsal (i.e. simulated surgery), where the surgeon had a variety of virtual surgical tools at their disposal and performed all the physical and mental processes one would in a real theatre environment e.g. performing surgery on a virtual reality simulator [41, 44–46].

For the purposes of surgical preparation, Patient-Specific (PS) three-dimensional virtual and synthetic anatomical models were built through the processes of 3D image reconstruction [11, 29, 31, 37, 41, 43–48] and additive manufacturing [23, 49] (i.e. Stereolithography [7, 50]) respectively. In some studies, physical cutting guides and implants were designed and manufactured during the rehearsal process and then sterilised and used during the real operation [11, 29, 31, 37, 41, 43–48].

A variety of medical imaging modalities are used for image 3D reconstruction including various types of Magnetic Resonance Imaging (MRI) [11, 29, 31, 37, 41, 43–48], Computed Tomography (CT) [7, 8, 10, 11, 23, 29, 31, 37, 41, 44–47, 49, 50] and more specialised imaging such as Diffusion Tensor Imaging (DTI) [43].

Comparators

Two types of comparisons were used in the included studies: (i) results of rehearsals were compared to the ones of real operations (i.e. patients act as their own controls) [41, 44, 45] (ii) preoperative preparation methods were compared to standard treatment or computed aided surgery (i.e. two distinct groups of patients) [15, 21, 38, 51]. The overall outcome in question was similarity between rehearsal and real procedure on the first occasion and assessment of possible superiority of the rehearsed procedures compared to non-rehearsed ones (evaluating for possible differences) in the second type of comparisons.

Type of outcomes

Descriptive synthesis of data regarding measured outcomes yielded the following commonly emerging themes: (i) accuracy of pre-operative preparation methods and (ii) clinical outcomes.

Accuracy of pre-operative preparation methods

Accuracy of the pre-operative preparation methods is reported using several outcome measures (Table 2). The most frequently used were (i) number of cases in which the preoperatively formulated plan was successfully followed [7, 10, 14–16, 19, 20, 25, 27–29, 31, 32, 34, 35, 37, 39, 47, 49, 52, 53] (ii) anatomical accuracy of models compared to operative anatomy [7, 46], and/or (iii) validity of the pre-operative processes, as reported by surgeons/surgical team [41, 44–46, 48]. The results for accuracy range from 66.7–100% (Figure 2).

Figure 2. Above: Similarity between anatomy and surgical plan during rehearsal compared with real procedure. Size of circles is indicative of sample size. Below: Face and content validity of preoperative preparation processes.

Table 2. Accuracy of pre-operative preparation methods and immediate surgical results. Additional information regarding accuracy and clinical results can be found in figures 2, 4 and 5.

Study	Good clinical outcome - Major complications
Perry et al. [23]	4/5 (80%) selected cases presented had a satisfactory outcome
Kockro et al. [11]	4 illustrative cases presented Total tumour excision in 3/4 (75%) cases
Lo et al. [22]	Symmetry and normal orbital contours achieved in all cases No complications (29–55 months f/u)
Leong et al. [25]	NIP
van Steenberghe et al. [50]	24/27 (88.9%) implants pass one year control - Bruxism 6/27 (22.2%), 4/27 inflammation of the gingiva
Radecka et al. [49]	Complete clearance of stones 5/8 (62.5%) - Mucosal perforation 1/8 (12.5%)
Gateno et al. [20]	Deformities corrected at 6 week f/u
Xia et al. [27]	NIP
Hislop et al. [44]	Successful operations (0% residual vessel stenosis) 3/5 (60%)
Lu et al. [53]	77.8% improvement in symptoms at 9 months f/u No complications
Ng et al. [47]	Complete resection 23/23 (100%) - 4.3% had additional neurological deficit post-operatively - 1/23 severely disabled due to post-operative complications
Dhanda et al. [17]	1.43 cm average improvement in mouth openining
Fornaro et al. [29]	Anatomic or satisfactory reduction of fracture 7/7 (100%) - No serious complications
Qiu et al. [43]	Total tumour resection 33/45 (73.3%) - Decrease >10% of effective fibre of pyramidal tract 7/45 (15.6%)
Dong et al. [28]	Resection margins free of tumour in all cases
Essig et al. [18]	2/3 good results
Ferrari et al. [48]	No Information Provided (NIP)
Hu et al. [31]	NIP
Tepper et al. [7]	NIP
Derand et al. [16]	Surgeons’ opinion: Good correlation of plan and surgical steps Calculated reduction in operation time 30min
Kanzaki et al. [54]	No conversion to open Margins free of cancer 3 complications – prolonged air leak, needed pleurodesis
Kerens et al. [33]	All guides fitted well during real surgery Good stability in all cases at 6 weeks f/u No complications
Nam et al. [9]	Good alignment of lower limb for: CAS: 92.7% - PCS:70.7%
Scolozzi [25]	Satisfactory reconstruction 2/2 0 complications
Shen et al. [37]	Satisfactory or anatomical reduction in 5/6 (83.3%) cases - No complications (0%)
Willaert et al. [45]	NIP
Adolphs et al. [14]	NIP
Desender et al. [41]	NIP
Hsu et al. [21]	NIP
Issa et al. [32]	No complications
Mandel et al. [57]	NIP
Pietsch et al. [35]	Satisfactory outcome (overall axis within 3^o) 47/51 (94%)
Schweizer et al. [36]	Improvement of wrist ROM at 1 year f/u Increase of wrist strength by 10% on average No complications (no instability or crepitus)
Small et al. [38]	No differences in length of procedure or blood loss 1 complication in control group and 0 in PS preparation group
Victor and Premanathan [39]	13/14 healed well 0 complications
Ayoub et al. [15]	2 transplants failed due to venous thrombosis
Franceschi et al. [30]	Significant improvement of WOMAC score after 1 year 3.7% (4 cases) stiffness: 1 required change of insert and 3 cases arthrolysis
Gander et al. [19]	No re-operation needed No complications (no visual impairment, no sensation of foreign body)
Haq et al. [8]	Improvement of mouth opening 3/5 (60%) - No facial nerve injury (0%) - Re-operation in 1/5 cases
Leeuwen et al. [34]	10/41 HKA angle >3^o from neutral axis
Makiyama et al. [46]	NIP
Fürnstahl et al. [10]	All (100%) osteotomies healed in 3–6 months - Joint effusion 1/3 (33.3%)
Isotani et al. [55]	Resection margins negative for cancerous tissue No urological complications
Kusaka et al. [56]	NIP
Li et al. [58]	Surgeon’s opinion: anatomy accurately represented
Li et al. [51]	Shorter op time and blood loss in intervention group No difference in complication rates
Schepers et al. [24]	6/7 flaps survived (average f/u 9.7 months) 1.2–2mm discrepancy between pre and postoperative model
Steinbacher [26]	NIP
Vlachopoulos et al. [40]	All osteotomies healed after mean time of 3.6 months Increased ROM and grip strength for both groups

Clinical outcomes

Immediate surgical outcomes, including peri-operative complications, were reported in most studies. For comparison, the number of cases that had a satisfactory outcome (e.g. anatomical reduction of a fracture) are presented as a percentage of the overall number of cases (Table 2).

The majority of studies reported satisfactory immediate surgical results (60–100%). Complication reporting was sparse with two exceptions: (i) van Steenberghe et al. who reported 6/27 cases of bruxism (involuntary grinding of the teeth), a complication known to be associated with immediate loading of implants in fully endentulous maxillae [50], and (ii) Fürnstahl et al. [10] who describe severe pain postoperatively due to incomplete procedure [medial compartment of the knee not repaired in theatre, despite having achieved repair during rehearsal]. The number of participants was too small (n = 3) to embark on further analysis (Table 2).

Surgeons’ feedback

Face validity [the extent to which a simulation appears similar to the real situation] [59] and content validity [validity of tests based on detailed examination of its contents] [60] where reported as above 3.4/5, demonstrating good realism (Figure 2).

Authors found the preparation methods to be useful in different ways such as: (i) better understanding of patient individual anatomy and pathology [11, 15, 16, 19, 28, 29, 31, 39, 41, 43, 44, 46–49, 54, 55], (ii) reducing operating time or number of procedures required [7–9, 16, 18, 20, 23, 24, 28, 37, 44, 49, 50], (iii) reducing complications or assisting in the avoidance of damage to vital structures [7, 8, 23, 29, 31, 37, 41, 43–48], and (iv) promoting a minimally invasive approach (e.g. reduce amount of dissection needed) [7, 29, 37, 43]. Drawbacks were also highlighted, for example technical issues encountered during the application of pre-operative rehearsals, including reliance of anatomical models on quality of imaging for accuracy [9, 11, 23, 41, 45, 47, 49]. Definition can be increased by increasing the number of images or acquiring thinner slices [9, 47, 49], however, additional resources would be needed and the ionisating radiation dose received by patients may increase [7]. In fact, three of the included studies reported that additional imaging was required [9, 10, 49].

Technical troubleshooting [11, 23, 41, 43, 45] as well as unrealistic biomechanical properties, mostly concerning soft tissue, [11, 31, 41, 43–47] have been reported. On occasion, the contralateral, healthy, side was used as a template for the repair of the diseased one [15, 18, 20, 25, 26, 39, 40], which could be troublesome in cases of bilateral pathology or asymmetry.

It should also be noted that many authors propose PS preoperative preparation for “difficult” cases (e.g. severely comminuted fractures or cranial base tumours surrounded by vital structures) [7, 9, 11, 23, 47, 48] and find no additional benefit in what they would traditionally consider a “straightforward” case [7, 10, 23, 44, 46].

A number of studies reported the cost of pre-operative preparation with PS anatomical models, ranging from hundreds to thousands pounds [14, 15, 25, 36, 54]. The manufacturing time ranged from hours to weeks [16, 19, 28, 55].

Quality assessment of included studies

The quality of the studies was appraised using the Cochrane Collaboration’s Tool for Assessing Bia [61], the Newcastle – Ottawa Quality Assessment Scale (NOQAS) [62] and three minute case series appraisal tool [63] for RCTs, cohort and case control studies and case series respectively (Figure 3).

Figure 3. Quality assessment scores. a. NOQAS b. Three minute case series appraisal tool.

RCTs

Introduction of bias to the study conducted by Small et al. [38] is very unlikely because enough information is given regarding the randomisation and the concealment allocation processes. The assessors of the outcome were blinded and there was sufficient completeness of outcome data. The authors reported both positive and negative results, reducing the possibility of reporting bias. There do not, however, appear to have taken into account personnel blinding, which would be practically very difficult [38].

In comparison, Ayoub et al. [15] do not provide information on how randomisation took place or if there was allocation concealment or personnel, and patient and assessor blinding. In regards to the reported outcomes there were data provided about the clinical results but not about the accuracy of the pre-operative preparation technique. Finally, introduction of reporting bias is unlikely because both positive and negative results are reported [15].

Case-series and non-randomised trials

The majority of case series and non-randomised trials are well designed as shown in Figure 3. All non-randomised trials scored six or more stars out of maximum nine and most case series had more than five (out of maximum eight) elements of well-designed case series.

Meta-analysis

Meta-analysis was applied where permitted by similarity of the research question and the measured outcomes. Hislop et al. [44], Desender et al. [41] and [45] all assessed the likeness of rehearsals and real procedures in vascular surgery and employed three common outcomes to do so (i.e. time to complete procedure, fluoroscopy time and fluoroscopy volume) (Figure 4). The results of the meta-analysis demonstrate that although rehearsals were significantly quicker than real procedures (SMD = −1.56 [−2.19, −0.93] P < 0.00001), the other two outcomes measured during the rehearsal, resembled the results of the real procedure (fluoroscopy time (min): SMD = −0.1 [−0.63, 0.42] P = 0.7, fluoroscopy volume (ml): SMD= −0.43 [−0.97, 0.11] P = 0.12).

Figure 4. Meta-analysis comparing rehearsals and real procedures. a. Comparison of time to complete procedure b. Comparison of fluoroscopy time c. Comparison of fluoroscopy volume.

Li et al. [51], Ayoub et al. [15], Small et al. [38], and Hsu et al. [21] recruited two distinct groups of patients to compare the clinical results of surgical procedures that were rehearsed to standard surgical treatment, while Nam et al. [9] compared the former to real time computer assisted surgery. The pre-rehearsed operations were completed in significantly less time (SMD −0.47 [−0.79, −0.16] P = 0.003) but the immediate clinical outcome was similar for practiced and not practiced operations (SMD =0.03 [−0.23, 0.29] P = 0.82) (Figure 5).

Figure 5. Meta-analysis of rehearsal compared with standard or other intervention (e.g. Nam et al patient specific preparation compared to computer assisted surgery). a. Time (min) to complete procedure. b. Linear translation (mm) of rehearsal outcome compared to the one of real procedure. Two different measured outcomes are included for Nam et al (for femoral and tibial compartment).

Discussion

This review demonstrates that patient specific pre-procedural are feasible and safe. The accuracy of the anatomical models and the immediate clinical outcomes of the rehearsed procedures were satisfactory. Meta-analysis comparing rehearsals and real procedures showed good correlation, whilst when operations following rehearsals were compared to non-rehearsed ones the former were performed quicker and yielded the same surgical outcome. Practical issues in the design and manufacturing of anatomical models are also highlighted in this review and can act as focus points for future studies.

The potential of patient-specific pre-procedural rehearsals shown in our review is also highlighted in the current literature. For example, [64] conducted a review on the use of 3D printing in medicine, giving a favourable opinion regarding the usefulness of additive manufacturing techniques for patient-specific preoperative planning and for building bespoken implants and prosthetics. However, the authors recognise that their conclusions are limited by the small number of cases currently reported and should be validated by larger scale trials.

Similarly, Pratt et al. [65] looked into preparation prior to foetal surgery, suggesting that although early evidence is promising, the exact impact on surgical outcomes cannot be accurately determined due to small numbers of reported cases. A beneficial impact was also reported by See et al. [66], investigating the impact of endovascular surgery rehearsals on trainees’ performance. The lack of randomised controlled trials was highlighted in both studies.

This systematic review has some limitations. Only two RCTs are included in this review whilst a significant volume of the presented evidence stems from case-series and non-randomised trials. This is a frequent occurrence in literature regarding emerging technologies in surgery [67]. Whilst some studies have shown case series to have a wider range of measured outcomes and estimates of effect size when compared to RCTs [68, 69], and to report the best achievable outcome rather then the one routinely accomplished [70], others do not find these conclusions to be true. For instance, Linde et al. [71] showed non-randomised trials to have consistent results to RCTs. Similarly, Dalzier et al. found a good correlation of case series and RCT results [68]. Nevertheless, case-series can demonstrate feasibility and safety.

Application of meta-analysis was limited by the diverse outcome measures employed in various studies and was reflected in the high heterogeneity found mostly in the comparison of two distinct groups of patients (I² test 80% an 86%). This could be due to various reasons, one of them being small sample size in each study, which is known to be associated with high heterogeneity [72]. Further, the potential variance in population, surgical specialty and intervention implementation may confound the results [73]. However, as we are inquisitive about the application of PS rehearsals in all surgical specialties we felt it was important to continue with this analysis and report the results.

Although the introduction of pre-operative rehearsals in routine clinical care should be preceded by the provision of high level evidence, they are worth exploring because they may lead to increased efficiency and reduced operating time, whilst maintaining safe outcomes. Rapid technological advances are expected to augment the accuracy of these procedures and reduced manufacturing times for virtual and synthetic anatomical models may increase the applicability of patient-specific preprocedural rehearsals.

Additional information

Funding

Leeds Teaching Hospitals Charitable Foundation