Sensor and machine learning-based assessment of gap balancing in cadaveric unicompartmental knee arthroplasty surgical training

SMART (self- monitoring analysis and reporting technology) and sensor based technology applications in trauma and orthopaedic surgery

Background

Innovations in implant designs and computer technology have led to the development of smart implants and prostheses in the field of orthopedics and trauma. Sensor-guided devices enable close monitoring of physical, chemical and biological environment around the implants, which has been purported to meliorate the intra-operative precision and post-operative surveillance of patients.

Objective

We evaluate the current applications of sensor-based technology in the management of patients with a spectrum of musculoskeletal conditions.

Material and methods

A thorough search of literature was performed on May 1, 2023, using the 5 databases (Embase, PubMed, Google Scholar, Cochrane Library and Web of Science) in order to identify suitable studies published between 2000 and 2023. All the studies which reported on SMART implants and Sensor based technology in the diverse sub-specialties of orthopedics like trauma, arthroplasty, spine surgery, infections, arthroscopy or sports medicine and paediatric orthopedics were considered. The keywords used for the search included 'Sensor technology', 'SMART implant' and "Orthopedics".

Results

Thirty articles were considered for this narrative review. A generation of SMART implants has been developed due to advancements in the microchip technology. Sensor based technology has been utilised in various subspecialties of arthroplasty (in assessing ligament balancing intra-operatively; or prosthetic loosening and gait analysis during follow-up), trauma surgery (as SMART instruments intra-operatively; or in the assessment of bone healing, distraction osteogenesis and functional recovery during follow-up), spine surgery (identification and protection of neural elements from iatrogenic injuries intra-operatively; and assessment of fusion across the instrumented levels during follow-up), paediatric orthopedics (compliance assessment for foot abduction orthosis in congenital talipes equinovarus), infection (monitoring of infection and biofilm formation), rehabilitation (gait analysis) and sports medicine (rotational stability and ligament compliance in patients with ligament injuries or reconstruction).

Conclusion

SMART implants and Sensor based technology have applications in the surgical planning, intra-operative performance, post-operative monitoring and patient surveillance diverse subspecialties of orthopedics and trauma. Future research in newer designs, cost-effective SMART implants and refinement of Sensor based technology will enhance Patient Related Outcome Measures (PROMs).

Lateral meniscus with tears or with histologic calcification does not increase the risk of lateral osteoarthritis after medial unicompartmental arthroplasty

PURPOSE

Meniscal tears or histological meniscal calcifications (in the absence of radiological chondrocalcinosis) are frequent in osteoarthritis. Whether lateral meniscal lesions influence clinical outcomes after medial unicompartmental knee arthroplasty (UKA) is unknown.

METHODS

We analyzed 130 patients (130 knees) with medial unicompartmental knee arthroplasties between 2005 and 2015. These 130 knees had full articular cartilage thickness in the lateral compartment and no radiological chondrocalcinosis on preoperative radiographs. The lateral meniscus was analyzed with preoperative MRI and a biopsy of the anterior horn at the time of surgery. Synovial fluid was collected and analyzed for calcium pyrophosphate dihydrate crystal deposition (CPPD crystals). Lateral meniscal tears were untreated when detected on MRI or during surgery, with the hypothesis that these tears on the opposite compartment would remain asymptomatic in medial UKA. At average 10-year follow-up, patients were evaluated with clinical and radiographic outcome, with a focus on the risk of joint space narrowing of the lateral femorotibial compartment.

RESULTS

CPPD crystals were present in the synovial fluid of 70 knees. Lateral meniscal tears were seen on MRI in 34 (49%) normal meniscuses of the 60 knees without CPPD crystals and in six other knees without histological meniscal calcification despite CPPD crystals. Histological calcification was present on 61 lateral meniscuses with 53 meniscal tears. The results showed no significant differences in the clinical outcomes between knees with lateral meniscal tears or lateral meniscal histological chondrocalcinosis or both lesions and those without these conditions. Additionally, radiographic progression of osteoarthritis in the opposite femorotibial compartment of the knee was not more frequent in patients with these meniscal issues. The ten year cumulative survival rates, measured by the need for total knee arthroplasty, were 91% for knees without meniscal lesions and 92% for knees with these lesions.

CONCLUSION

On this basis, treatment of meniscal tears of the lateral compartment and routine aspiration of the knee to assess for birefringent crystals in the planning of medial UKA do not appear necessary.

Intraoperative sensor technology quantifies inter-prosthesis pressure for predicting lower limb alignment after Oxford unicompartmental knee arthroplasty

Purpose: The aim of this study is to quantify inter-prosthetic pressures at different knee angles in Oxford unicompartmental knee arthroplasty (OUKA) and its correlation with postoperative lower limb alignment. Methods: This study included 101 patients (122 knees) who underwent OUKA from March 2022 to July 2022. The previously designed matrix flexible force sensor was used to measure the inter-prosthesis pressure of different knee joint angles during the UKA operation, and the force variation trend and gap balance difference were obtained. The correlation between inter-prosthesis pressure and postoperative lower limb alignment index including hip-knee-ankle angle (HKAA) and posterior tibial slope (PTS) was analyzed. The effect of PTS change (ΔPTS) on the inter-prosthesis pressure and the range of motion (ROM) of the knee joint was analyzed. Radiographic and short-term clinical outcomes of included patients were assessed. Results: The inter-prosthesis pressure of the different knee joint angles during the operation was not consistent. The mean inter-prosthesis pressure and gap balance difference were 73.68.28 ± 41.65N and 36.48 ± 20.58N. The inter-prosthesis pressure at 0° and 20° was positively correlated with postoperative HKAA (p < 0.001). ΔPTS was positively correlated with the pressure at the end of knee extension and negatively correlated with the pressure at the end of knee flexion (p < 0.001). The HKAA, ROM, degree of fixed knee flexion deformity, and knee society score of the included patients were significantly improved compared with those before the operation (p < 0.001). Conclusion: The inter-prosthesis pressure measured at the knee extension position can predict postoperative HKAA to some degree. Changes in PTS will affect the inter-prosthesis pressure at the end of flexion and end of knee extension, but this change is not related to the range of motion of the knee joint.

Gap balance difference of unicompartmental knee arthroplasty between hanging leg and supine leg position: a prospective cohort study

PURPOSE

Gap balance is critical in Oxford unicompartmental knee arthroplasty (OUKA) surgery; the effect of lower limb positioning on gap balance judgements has not been reported. There are two mean operative positions for OUKA patients, the hanging leg (HL) and the supine leg (SL) position. This study aimed to investigate the gap balance achieved by current UKA surgical techniques by using a force sensor, to compare the differences in gap balance between the two different positions, and to test whether the difference in gap balance leads to different outcomes in terms of component alignment and early post-operative clinical outcomes.

METHODS

This prospective study included 97 knees (76 patients), who underwent OUKA from June 1, 2020, to July 31, 2021, of which 67 knees underwent UKA in the supine leg position and the other 30 in the hanging leg position. When the operator was satisfied with the gap balance, the contact forces between the trial and the spacer block were measured at 90° of knee flexion (flexion gap) and 20° of knee flexion (extension gap) using a pre-developed matrix flexible force sensor. X-rays were reviewed three to five days after surgery. Knee Society Scores (KSS) were obtained at the six month follow-up.

RESULTS

Compared to the HL group, the contact force at the flexion gap was higher in the SL group: 55.15N (SD 43.36N) vs. 34.25N (SD 27.56N) (p < 0.05), whereas in the extension gap, there was no significant difference, 90.19 N (SD 43.36N) in the SL group and 86.72N (SD 43.08N) in the HL group (ns.). The contact force was greater in the extension gap than in the flexion gap in both groups (p < 0.01). The gap balance difference in the HL group was 52.46N (SD 31.33N), which was greater than that of the SL group at 35.03N (SD 19.50N) (p < 0.05). There were no significant differences in component alignment or lower limb mechanical alignment between the two groups. There was no significant difference in pre-operative and post-operative KSS between the two groups, while post-operative KSS was significantly higher in both groups compared to the pre-operative period.

CONCLUSION

The intra-operative contact forces between the flexion and extension gaps differed in the two groups; the hanging leg position appeared to produce a greater difference in the judgement of gap balance than the supine leg position, but this difference did not adversely affect the alignment of the component or the early post-operative clinical outcome.

Bone conductivity and spine fluoroscopy, Hand-Eye-Ear dialogue, during pedicle screw positioning: a new human cognitive system for precision and radiation-decrease; better than artificial intelligence and machine learning system?

PURPOSE

There is an increasing need for pedicle screw positioning while decreasing radiation exposure. This study compares intra-operative radiation dose using posterior internal fixation using impedancemetry-guided pedicle positioning by the Pediguard system versus standard free-hand sighting when surgery was performed with a trainee or expert surgeon.

MATERIAL AND METHODS

Using the electrical properties of bone, the Pediguard detects iatrogenic penetration of the pedicle wall and gives auditory feedback to the surgeon. A single centre, two surgeons (one experienced and the other novice) conducted a continuous prospective randomized study for one year. Twenty patients were randomized into one group (free-hand control group) receiving pedicle instrumentation without the use of the Pediguard and the second group receiving pedicle instrumentation with the use of the Pediguard. The total screw placement times and fluoroscopic times for each screw was recorded and pedicle screw position was analyzed on post-operative CT scan.

RESULTS

Among the 104 screwed pedicles, 22 unrecognized perforations were detected by CT scan, while no perforation signal was observed intra-operatively. Only one perforation was greater than 2 mm. The overall screwing time was 4.33 ± 1.2 minutes per screw for experienced surgeon and 5.84 ± 2.5 minutes per screw for the novice. Pediguard did not increased significantly the time (0.3 mn per screw) for the experienced surgeon, but the time with Pediguard was longer (2 mn more per screw) for the novice surgeon, particularly at the thoracic level. The overall fluoroscopic average time per screw for the experienced surgeon is 5.8 ± 2.3 s and 10.4 ± 4.5 s for the novice surgeon. For the novice surgeon, radiation time reduced from 12 (without Pediguard) to 6 s (with Pediguard). There was no significant difference for the experienced surgeon in terms of improvement in radiation time with the use of Pediguard.

CONCLUSION

The overall time was longer for the novice surgeon with the Pediguard system, but allowed to decrease by 50% the fluoroscopy time.

Concerns surrounding application of artificial intelligence in hip and knee arthroplasty

Literature surrounding artificial intelligence (AI)-related applications for hip and knee arthroplasty has proliferated. However, meaningful advances that fundamentally transform the practice and delivery of joint arthroplasty are yet to be realized, despite the broad range of applications as we continue to search for meaningful and appropriate use of AI. AI literature in hip and knee arthroplasty between 2018 and 2021 regarding image-based analyses, value-based care, remote patient monitoring, and augmented reality was reviewed. Concerns surrounding meaningful use and appropriate methodological approaches of AI in joint arthroplasty research are summarized. Of the 233 AI-related orthopaedics articles published, 178 (76%) constituted original research, while the rest consisted of editorials or reviews. A total of 52% of original AI-related research concerns hip and knee arthroplasty (n = 92), and a narrative review is described. Three studies were externally validated. Pitfalls surrounding present-day research include conflating vernacular (“AI/machine learning”), repackaging limited registry data, prematurely releasing internally validated prediction models, appraising model architecture instead of inputted data, withholding code, and evaluating studies using antiquated regression-based guidelines. While AI has been applied to a variety of hip and knee arthroplasty applications with limited clinical impact, the future remains promising if the question is meaningful, the methodology is rigorous and transparent, the data are rich, and the model is externally validated. Simple checkpoints for meaningful AI adoption include ensuring applications focus on: administrative support over clinical evaluation and management; necessity of the advanced model; and the novelty of the question being answered.

Cite this article: Bone Joint J 2022;104-B(12):1292–1303.

Exploring the relationship between bearing extrusion and postoperative persistent pain in Oxford unicompartmental knee arthroplasty: A trajectory measurement study

Objective: The aim of the study is to explore the relationship between the extrusion of the meniscus bearing and postoperative persistent pain of Oxford unicompartmental knee arthroplasty.

Methods: Patients undertaking Oxford UKA from January 2019 to June 2020 were retrospectively analyzed. Intraoperatively, the displacement and movement trajectory of the meniscus bearing was recorded by the specially designed gridding mold of the tibial component. The k-means clustering analysis was applied based on the incidence of postoperative persistent knee pain and the bearing extrusion distance. The intraoperative meniscus bearing movement trajectories were analyzed between the two groups and the patients’ clinical outcomes and radiographic assessments.

Results: The k-means clustering analysis indicated that the extrusion of the bearing of 5 mm was the grouping standard. There were 27 patients with 30 knees in the extrusion group and 58 patients with 68 knees in the non-extrusion group. The proportion of optimal bearing movement trajectories in the extrusion group was significantly lower than that in the non-extrusion group (p < 0.05). Postoperative persistent knee pain occurred in six cases (6.1%), with four and two cases in the extrusion and non-extrusion groups, respectively. The incidence of postoperative persistent knee pain in the extrusion group was higher than that of the non-extrusion group (p < 0.05). Radiographic assessment showed that the continuity of the femoral and tibial components in the extrusion group was greater than that in the non-extrusion group (p < 0.05). However, there were no differences in pre- and postoperative HKAA, the varus/valgus degree of both femoral and tibial components, and the flexion/extension angles of the femoral component, and the tibial slope also showed no statistical difference (p > 0.05).

Conclusion: For Oxford mobile-bearing UKA, the extrusion of meniscus bearing over 5 mm may increase the incidence of postoperative persistent knee pain, while the improvement of the bearing movement trajectory can effectively reduce this complication.

Can mobile-bearing unicompartmental knee arthroplasty achieve natural gap-balancing? An observational study with a novel pressure sensor

Background

Mobile-bearing unicompartmental knee arthroplasty (MB-UKA) is an effective treatment for anteromedial knee osteoarthritis. Meticulous intraoperative soft tissue balancing remains challenging yet consequential for a successful operation. Currently, surgeons rely mostly on their experience during soft tissue balancing, yielding unreproducible results. The purpose of this study was to quantified measure the soft tissue tension of medial compartment and determine if an optimal "target" tension values with the natural state exists.

Methods

This was an observational study of 24 consecutive patients. All 30 UKAs were performed by a single surgeon. The piezoresistive sensor was custom designed to fit in the medial compartment gap. Contact pressures were measured at 5 angular positions of the knee intraoperatively: 0°, 20°, 45°, 90°, and 110° of flexion. The change in pressure from extension (20° position) and flexion (110° position) was also calculated (E-FPD). Data on age, sex, body mass index, operative side, and bearing size were collected. Outcome measures were measured at baseline and at the 6-month postoperative follow-up; Oxford Knee Score, visual analog scale score, and range of motion were compared to evaluate clinical outcomes.

Results

There was a significant improvement in patients in all measured outcomes at 6 months from baseline (P < 0.05). The E-FPD of 14.9 N (8.9, 24.6) was indicative of appropriate soft tissue balancing throughout the functional range of knee motion. Of 30 knees, 22 were 3-mm bearing and 8 were 4- or 5-mm bearing. The pressure data of the 3-mm bearing group was larger than that of the non-3-mm bearing group for each knee flexion degree, but the difference was not statistically significant (P > 0.05).

Conclusions

Objective data from sensor output may assist surgeons in decreasing loading variability during MB-UKA. The data suggested that MB-UKA could not accurately restore soft tissue tension to the natural state, which was related to the inability of MB-UKA surgical instruments to fine adjust the bone cut and soft tissue release.

Study registration

Chinese Clinical Trial Registry (http://www.chictr.org.cn): ChiCTR1900024146.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03255-6.