Interventional procedure overview of synthetic cartilage implant insertion for first metatarsophalangeal joint osteoarthritis (hallux rigidus)

Function

In a randomised controlled trial (RCT) of 219 patients, 79% of patients who had implant insertion and 62% of patients who had arthrodesis had a successful outcome in the intention-to-treat population. This was defined as improvement from baseline in the VAS of pain of 30% or more at 12 months, maintenance of function from baseline in Foot and Ankle Ability Measure (FAAM) sports subscore at 12 months, and absence of major safety events (p<0.001 for non-inferiority). In a modified intention-to-treat population (all patients who had treatment), the proportion of patients with a successful outcome was 80% in both groups (p<0.0075 for non-inferiority).The mean FAAM sports score was 66.6 in the implant group (n=120) and 78.6 (n=42) in the arthrodesis group at 6-month follow up (p=0.01). At 1 year, the scores were 75.8 (n=120) and 84.1 (n=43; p=0.043), and at 2 years they were 79.5 (n=113) and 82.7 (n=41) respectively (p=0.461). The mean SF-36 physical functioning scores were 72.3, 78.9 and 83.2 in the implant group at 6 months (n=124), 1 year (n=123) and 2 years (n=116) respectively and 82.8, 83.7 and 85.1 respectively in the arthrodesis group (n=43, n=43 and n=41; p=0.021, p=0.247 and p=0.613) (Baumhauer, 2016). Success rates between the groups were similar when stratified by hallux rigidus grade, gender, age, body-mass index, symptom duration, previous surgery status, preoperative VAS pain, hallux valgus and range of motion (Goldberg, 2017). In a case series of 119 patients who were in the implant group of the RCT, the mean change in FAAM sports was 47.9 points (95% confidence interval [CI] 39.3 to 57.1) at final follow up (mean 5.8 years). Of 105 patients who still had the implant at final follow up, 97 (93%) had a clinically significant improvement in FAAM sports score (Glazebrook, 2019).

In a non-randomised comparative study of 72 patients, the mean postoperative FAAM sports scores were 76% for patients who had implant insertion and 81% for patients who had arthrodesis (p>0.3, Brandao, 2020a). In a non-randomised comparative study of 133 patients treated by cheilectomy and Moberg osteotomy with or without a synthetic cartilage implant, there were statistically significant improvements in the Patient-Reported Outcomes Measurement Information System (PROMIS) for physical function, pain interference, pain intensity, and global physical health domains within each group after surgery (p<0.01). Patients who did not have an implant inserted had statistically significantly higher postoperative physical function, lower pain intensity and a greater improvement in physical function compared with those patients who did have an implant (Chrea, 2020). In a non-randomised comparative study of 78 patients who had synthetic cartilage implant insertion or cheilectomy, the mean postoperative FAAM sports scores were 74.9% and 82.7%, respectively (p=0.11) (Brandao, 2020c).

In a case series of 55 patients, the mean objective FAAM ADL scores improved from 64% at baseline to 87% at follow up (mean 21 months; p<0.0001) (Brandao, 2020b).

In a case series of 60 patients (64 implants), the mean PROMIS physical function score was 42 at follow up (mean 15 months), reported as corresponding to mild dysfunction (Cassinelli, 2019). In a case series of 103 patients, the mean PROMIS physical function score improved from 44.7 to 48.2 at follow up (mean 14 months; p=0.009) (Eble, 2020).

In a case series of 16 patients (18 implants) who had MRI after the implant insertion because of persistent pain or dysfunction at the metatarsophalangeal joint, the mean PROMIS physical function score was 41 (range 27 to 56) at follow up (mean 21 months), reported as corresponding to moderate dysfunction (An, 2020).

In a non-randomised comparative study of 181 patients, the mean PROMIS physical function score improved from 47.1 to 51.1 in patients who had synthetic cartilage implant insertion and from 43.9 to 45.9 in patients who had arthrodesis at final follow up (mean 27 months and 38 months respectively). The difference in scores between the groups was statistically significant at both baseline and final follow up (p<0.01) (Joo, 2021).

In a case series of 90 patients (96 implants), the range of motion was better after surgery in 69% (66/96) of implants and worse in 24% (23/96) of implants (Lee, 2021).

Dorsiflexion

In the RCT of 219 patients, the mean active peak dorsiflexion angles were statistically significantly higher in the implant group compared with the arthrodesis group after treatment. The results were 25.1, 28.1, 28.8 and 29 at 6 weeks, 6 months, 1 year and 2 years, respectively, in the implant group compared with 13.0, 14.9, 16.0 and 15.1 in the arthrodesis group; p<0.0001 for all time periods (Baumhauer, 2016).

Pain

In the RCT of 219 patients, the VAS pain scores were statistically significantly higher in the implant group compared with the arthrodesis group after treatment. The scores were 33.2, 28.9, 17.8 and 14.5 at 6 weeks, 6 months, 1 year and 2 years, respectively, in the implant group compared with 17.2, 11.7, 5.7 and 5.9 in the arthrodesis group; p<0.0001, p<0.000, p<0.0011, p<0.002 (Baumhauer, 2016).

In the case series of 60 patients, the mean PROMIS pain interference score was 60 at follow up (mean 15 months), reported as corresponding to mild pain (Cassinelli, 2019). In the case series of 103 patients, the mean pain interference score reduced from 58.0 to 52.5 (p<0.0001) and pain intensity score reduced from 50.9 to 43.5 (p<0.0001) at follow up (mean 14 months) (Eble, 2020).

In the non-randomised comparative study of 78 patients who had synthetic cartilage implant insertion or cheilectomy, the MOXFQ pain score was 27.5 and 27.2, respectively, after the procedure (p=0.6818) (Brandao, 2020c).

In the case series of 16 patients, the mean PROMIS pain interference score was 63 at follow up (mean 21 months), reported as corresponding to moderate pain (An, 2020).

In the non-randomised comparative study of 181 patients, the mean PROMIS pain interference score improved from 55.6 to 49.4 in patients who had synthetic cartilage implant insertion and from 57.4 to 48.2 in patients who had arthrodesis at final follow up (mean 27 months and 38 months, respectively). The difference between the groups was not statistically significant (Joo, 2021).

In the case series of 90 patients (96 implants), the mean VAS pain score reduced from 7.9 at baseline to 1.5 after the procedure (p<0.001) (Lee, 2021).

Quality of life

In the RCT of 219 patients, the mean FAAM ADL scores reported at 6 weeks, 6 months, 1 year and 2 years were 69.0, 82.7, 88.6 and 90.4 in the implant group compared with 59.6, 89.9, 94.1 and 94.6 in the arthrodesis group (p=0.008, p=0.014, p=0.0176, p=0.082), respectively (Baumhauer, 2016). In the non-randomised comparative study of 78 patients who had synthetic cartilage implant insertion or cheilectomy, the MOXFQ index was 27.0 and 14.1, respectively, after the procedure (p=0.012) (Brandao, 2020c).

Need for further surgery or implant survivorship

In the RCT of 219 patients, 11% (17/152) of patients who had synthetic cartilage implant insertion had the implant removed or another operation at the 2-year follow up. Of these, 14 had conversion to arthrodesis, 1 had joint manipulation for motion, 1 had debridement and implant repositioning and 1 had Moberg osteotomy of the proximal phalanx for improved toe positioning, motion and pain relief (Baumhauer, 2016). In the case series of 119 patients from the implant group of the RCT, 9 (8%) patients had implant removal and conversion to arthrodesis between years 2 and 5. Kaplan−Meier implant survivorship was 85% at 5.8 years of follow up (Glazebrook, 2019).

In the non-randomised comparative study of 72 patients, 1 patient in the implant group had revision to arthrodesis 17 months later because of persistent pain (Brandao, 2020a). In the non-randomised comparative study of 133 patients, 5% (3/60) of patients who had an implant needed revision surgery compared with 1% (1/73) of patients who did not have an implant (Chrea, 2020).

In the case series of 60 patients (64 implants), reoperation was needed after 20% (13/64) of procedures. This included 5 conversions to fusion, 4 lysis of adhesions, 1 Moberg osteotomy and 3 implant exchanges with bone grafting. Conversion to fusion was done at a mean of 16 months after the implant insertion (Cassinelli, 2019). In the case series of 55 patients, there were 2 revisions at 14 and 17 months, respectively. Of the 55 patients, 15 (27%) had manipulation under anaesthesia and steroid and local anaesthetic injection at 12 weeks after the operation because of stiffness (Brandao, 2020b).

In the case series of 103 patients, the revision rate was 2% (2/103). One patient had a conversion to arthrodesis at 14 months after the index procedure; the implant was noted to be loose, with inflammation and fibrous tissue at the joint. The other patient had a hemiarthroplasty with synthetic cartilage implant, done at 21 months after the operation. The implant was found to have marked loss of contour at the medial aspect of the toe (Eble, 2020).

In the case series of 16 patients, the reoperation rate by 2 years was 38% (6/16), including 2 conversions to fusion (An, 2020).

In the non-randomised comparative study of 181 patients, 3% (2/59) of patients who had a synthetic cartilage implant inserted had the implant removed and conversion to arthrodesis after 12 and 21 months, respectively (Joo, 2021).

In the case series of 90 patients (96 implants), 2% (2/96) of implants were revised to arthrodesis at 13 and 23 months, respectively, after the index procedure (Lee, 2021).

Patient satisfaction

In the case series of 119 patients, 56% (59/105) of patients strongly agreed and 31% (33/105) agreed to the statement that their overall wellbeing had improved. When asked if they would have the procedure again, 93% (99/106) said they would and 7% (7/106) said they would not (Glazebrook, 2019).

In the case series of 60 patients (64 implants), 14% (9/64) of patients were very satisfied, 28% (18/64) were satisfied, 20% (13/64) were neutral, 11% (7/64) were unsatisfied and 27% (17/64) were very unsatisfied after the procedure. The proportion of patients who said they would have the same surgery again was 66% (42/64) (Cassinelli, 2019). In the case series of 55 patients, patient satisfaction was 89% (Brandao, 2020b).

In the case series of 16 patients, the mean satisfaction rating was 2.25 on a 5‑point Likert scale (An, 2020).

In the case series of 90 patients (96 implants), patients were very satisfied after 42% (40/96) of implants, satisfied after 32% (31/96), neutral after 8% (8/96), unsatisfied after 8% (8/96) and very unsatisfied after 9% (9/96) of implants (Lee, 2021).