To the Editor,
Recently, The National Healthcare Institute of the Netherlands reviewed several publications on joint distraction to decide on reimbursement of this treatment in the Netherlands. During their survey, The National Healthcare Institute also reviewed the publication of Jansen et al. 1 published in Cartilage.
On reviewing the publication, they found an inconsistency between described data and data presented in tables. Based on that they contacted us as main authors and inquired the correct data. As such, an immediate thorough recheck on all source data files was performed. It was discovered that there was indeed an inconsistency present for some of the parameters.
We feel that despite the minor difference between the published data and the correct data, and despite the fact that the general conclusion and discussion of the publication do not change, this needs to be amended. As such, we will outlie the textual changes by presenting the updated text by paragraph, with changes shown in italics, and present updated versions of Table 2 , Table 3 , and Figure 1 .
Table 2 (Amended).
Baseline Characteristics of Patients from the 2 Randomized Controlled Trials. a
| Characteristic | KJD vs. TKA |
KJD vs. HTO |
||
|---|---|---|---|---|
| KJDTKA (n = 19) | TKA (n = 34) | KJDHTO (n = 20) | HTO (n = 41) | |
| Male gender, n (%) | 8 (42) | 12 (35) | 15 (75) | 24 (58) |
| BMI, kg/m2 | 27.1 (3.8) | 28.4 (6.0) | 27.4 (3.3) | 27.1 (3.3) |
| Age, years | 55.7 (7.4) | 55.4 (6.0) | 51.2 (5.8) | 49.3 (6.3) |
| Axis, deg | 2.1 (7.0) | 2.8 (6.2) | 5.9 (2.7) | 6.1 (2.2) |
| Kellgren-Lawrence grade | 4 (1.0) | 3 (0.0) | 3 (1.8) | 3 (1.0) |
| Grade 0, n (%) | 0 (0) | 0 (0) | 0 (0) | 1 (2) |
| Grade 1, n (%) | 0 (0) | 0 (0) | 5 (25) | 4 (10) |
| Grade 2, n (%) | 1 (5) | 7 (21) | 4 (20) | 11 (27) |
| Grade 3, n (%) | 8 (42) | 21 (62) | 10 (50) | 21 (51) |
| Grade 4, n (%) | 10 (53) | 6 (18) | 1 (5) | 4 (10) |
| Flexion, deg | 121 (10.5) | 123 (7.7) | 130 (7.2) | 132 (8.5) |
| Total WOMAC (0-100) | 49.5 (10.8) | 46.0 (12.4) | 57.8 (17.8) | 51.9 (17.0) |
| Total KOOS (0-100) | 38.4 (9.2) | 35.8 (11.6) | 45.7 (14.4) | 40.6 (12.8) |
| VAS pain (100-0) | 68.2 (17.4) | 72.6 (16.4) | 52.5 (22.1) | 64.4 (18.1) |
| EQ-5D (0-1) | 0.66 (0.25) | 0.61 (0.24) | 0.70 (0.20) | 0.72 (0.18) |
| ICOAP Combined (100-0) | 46.4 (16.1) | 56.8 (18.2) | 46.2 (18.4) | 50.0 (18.6) |
| SF-36 PCS (0-100) | 33.6 (9.0) | 31.3 (7.2) | 37.7 (6.7) | 35.8 (8.1) |
| SF-36 MCS (0-100) | 54.5 (8.4) | 54.0 (9.8) | 55.0 (8.2) | 55.1 (8.5) |
| Minimum JSW, mm | 0.65 (1.3) | – | 0.49 (0.7) | 0.54 (1.0) |
| Mean JSW, mm | 1.93 (2.0) | – | 1.99 (1.5) | 1.89 (1.2) |
EQ-5D = EuroQol-5D-3L; HTO = high tibial osteotomy; ICOAP = Intermittent and Constant Osteoarthritis Pain score; JSW = joint space width; KJDTKA = knee joint distraction patients from the clinical trial comparing KJD with TKA; KJDHTO = knee joint distraction patients from the clinical trial comparing KJD with HTO; KOOS = Knee Injury and Osteoarthritis Outcome Score; MCS, mental component summary; PCS = physical component summary; SF-36 = Short Form 36; TKA = total knee arthroplasty; VAS = visual analogue scale; WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index.
Mean values and standard deviation are given for all continuous parameters. For the categorical Kellgren-Lawrence grade the median and interquartile range are given. Separate Kellgren-Lawrence grades and gender are given in numbers and percentages. Ranges from worst to best are indicated for the clinical parameters.
Table 3 (Amended).
Two-Year Changes in Clinical and Structural Parameters. a .
| Parameter | KJD vs. TKA | KJD vs. HTO | |||||
|---|---|---|---|---|---|---|---|
| KJDTKA (n = 19) | TKA (n = 34) | P b | KJDHTO (n = 20) | HTO (n = 41) | P b | ||
| WOMAC (0-100) | Total | 30.4* (23.0-37.9) | 42.4* (38.1-46.8) | 0.011 | 21.6* (13.8-29.4) | 29.2* (23.6-34.8) | 0.294 |
| Stiffness | 30.9* (22.3-39.4) | 34.4* (27.2-41.6) | 0.277 | 16.3* (5.2-27.3) | 24.8* (18.2-31.4) | 0.314 | |
| Pain | 28.5* (18.5-38.4) | 45.4* (39.6–51.2) | 0.003 | 23.7* (15.5-31.9) | 31.9* (25.4-38.3) | 0.416 | |
| Function | 31.0* (23.0-38.9) | 42.5* (38.2–46.9) | 0.033 | 21.6* (13.7-29.6) | 28.9* (23.1-34.7) | 0.319 | |
| KOOS (0-100) | Total | 28.7* (20.4-37.1) | 43.3* (38.7-47.9) | 0.002 | 21.6* (14.4-28.8) | 30.0* (25.0–35.1) | 0.109 |
| Symptom | 28.3* (20.5-36.0) | 33.6* (27.5-39.6) | 0.212 | 16.7* (10.2-23.3) | 22.6* (17.7-27.5) | 0.276 | |
| Pain | 29.8* (20.3-39.3) | 47.9* (42.3-53.5) | 0.001 | 25.7* (17.6-33.8) | 32.5* (27.0-38.1) | 0.347 | |
| Function | 31.0* (23.0-38.9) | 42.5* (38.2-46.9) | 0.034 | 21.6* (13.6-29.6) | 28.9* (23.1-34.8) | 0.317 | |
| Sport | 28.3* (14.6-42.0) | 49.2* (41.0-57.5) | 0.007 | 25.7* (15.1-36.3) | 33.8* (25.3-42.3) | 0.314 | |
| QOL | 26.3* (13.7-38.8)* | 44.5* (36.4-52.6) | 0.015 | 17.7* (10.1-25.2) | 32.2* (25.4-39.0) | 0.013 | |
| VAS (100-0) | Pain | −36.5* (−49.8 to −23.2) | −56.0* (−64.8 to −47.3) | 0.014 | −21.8* (−34.8 to −8.8) | −38.4* (−47.1 to −29.8) | 0.269 |
| EQ-5D (0-1) | Index | 0.10 (−0.02 to 0.22) | 0.27* (0.16-0.38) | 0.023 | 0.16* (0.06-0.26) | 0.11* (0.04-0.19) | 0.564 |
| ICOAP (100-0) | Constant | −33.0* (−43.5 to −22.5) | −48.8* (−58.0 to 39.6) | 0.109 | −29.3* (−39.6 to −19.0) | −29.8* (−38.5 to −21.0) | 0.913 |
| Intermittent | −32.6* (−44.0 to −21.3) | −44.9* (−52.4 to −37.5) | 0.355 | −25.3* (−35.0 to −15.7) | −31.9* (−39.7 to −24.0) | 0.559 | |
| Combined | −32.8* (−43.6 to −22.0) | −45.6* (−54.4 to −38.7) | 0.216 | −26.7* (−36.3 to −17.1) | −30.4* (−37.7 to −23.1) | 0.692 | |
| SF-36 (0-100) | PCS | 5.3 (−0.5 to 11.1) | 17.9* (14.6-21.2) | <0.001 | 6.5* (2.6-10.4) | 11.9* (8.9-14.9) | 0.051 |
| MCS | 0.4 (−6.0 to 6.7) | −0.6 (−6.6 to 5.3) | 0.728 | 1.0 (−2.9 to 4.9) | −1.1 (−4.5 to 2.3) | 0.468 | |
| Flexion (deg) | Knee | – | – | – | 1.4 (−2.3 to 5.0) | −2.0 (−5.0 to 1.0) | 0.254 |
| JSW (mm) | Minimum | 0.90* (0.22-1.57) | – | – | 0.94* (0.50-1.37) | 0.62* (0.31-0.92) | 0.233 |
| Mean | 0.99* (0.32-1.65) | – | – | 0.83* (0.34-1.32) | 0.88* (0.58-1.18) | 0.884 | |
EQ-5D = EuroQol-5D-3L; HTO = high tibial osteotomy; ICOAP = Intermittent and Constant Osteoarthritis Pain score; JSW = joint space width; KJDTKA = knee joint distraction patients from the clinical trial comparing KJD with TKA; KJDHTO = knee joint distraction patients from the clinical trial comparing KJD with HTO; KOOS = Knee Injury and Osteoarthritis Outcome Score; MCS, mental component summary; PCS = physical component summary; SF-36 = Short Form 36; TKA = total knee arthroplasty; VAS = visual analogue scale; WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index.
Mean and 95% confidence intervals are given and ranges from worst to best are indicated for the clinical parameters. Changes between patient groups from each separate trial (KJD/TKA and KJD/HTO) are compared and corrected for baseline values using linear regression. Flexion parameters were not measured at 2 years in the KJD/TKA and TKA groups.
Boldfaced P values indicate statistically significant differences between groups.
Statistically significant change (P < 0.05) compared with baseline.
Figure 1.
Total WOMAC (A) Total Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) score over 2 years, for the TKA-indicated subgroups (KJDTKA and TKA), represented as mean ± standard error of the mean (SEM). (B) Two-year change in WOMAC score for each individual TKA-indicated patient (markers) and for the KJDTKA and TKA subgroups (average ± SEM, dashes). (C) Total WOMAC score over 2 years for the HTO-indicated subgroups (KJDHTO and HTO), represented as mean ± SEM. (D) Two-year change in WOMAC score for each individual HTO-indicated patient (markers) and for the KJDHTO and HTO subgroups (average ± SEM, dashes). HTO, high tibial osteotomy; TKA, total knee arthroplasty; HTO, high tibial osteotomy; KJDTKA = knee joint distraction patients from the clinical trial comparing KJD with TKA; KJDHTO = knee joint distraction patients from the clinical trial comparing KJD with HTO.
The P values above subgroups indicate significant 2-year changes while the P values between subgroups indicate the differences between each 2 groups.
Abstract
At 2 years, the total WOMAC score (KJDTKA: +30.4 [95% CI 23.0-37.9] points; TKA: +42.4 [95% CI 38.1-46.8]; KJDHTO: +21.6 [95% CI 13.8-29.4]; HTO: +29.2 [95% CI 23.6-34.8]; all: P < 0.05) and radiographic minimum JSW (KJDTKA: +0.9 [95% CI 0.2-1.6] mm; KJDHTO: +0.9 [95% CI 0.5-1.4]; HTO: +0.6 [95% CI 0.3-0.9]; all: P < 0.05) were still increased for all groups.
Results: Patient-Reported Outcome Measures
As primary outcome, a clear and clinically significant improvement in total WOMAC score ( Fig. 1 ) was present 2 years after treatment for all 4 groups (KJDTKA Δ30; TKA Δ42; KJDHTO Δ22; HTO Δ29; all Ps < 0.001).
Results: Patient-Reported Outcome Measures: KJD Versus TKA
The TKA group showed statistically significantly greater improvements than the KJDTKA group for most of the clinical parameters ( Table 3 ), including the total WOMAC and total KOOS and most of their subscales (all Ps < 0.035), the VAS pain (P = 0.014), the EQ-5D (P = 0.023), and the SF-36 PCS (P < 0.001). There was no significant difference for WOMAC stiffness (P = 0.277), KOOS stiffness (P = 0.212), the ICOAP (P = 0.216), and ICOAP subscales (both P > 0.108). As the change in WOMAC over 2 years was on average considerably more than 15 points and with that clinically significant, this change in WOMAC was not clinically relevantly different between both treatments: Δ30.4 points (95% CI 23.0-37.9) versus Δ42.4 (95% CI 38.1-46.8). The total WOMAC score at 2 years was 81.0 (95% CI 73.3-88.7) for the KJDTKA group and 88.1 (95% CI 84.2-91.9) for the TKA group, indicating no clinically significant difference cross-sectionally at 2 years in the primary outcome.
Results: Patient-Reported Outcome Measures: KJD Versus HTO
The improvements over 2 years follow-up in total WOMAC score as primary outcome was clinically relevant for both treatment arms, exceeding the 15 points, whereas the change over 2 years was not clinically relevantly different between both treatments: Δ21.6 points (95% CI 13.8-29.4) versus Δ29.2 points (95% CI 23.6-34.8).
Results: Radiographic Evaluation: KJD Versus TKA
In the KJDTKA group, the minimum JSW increased significantly from 0.69 (±0.33) mm at baseline to 1.58 (±0.28) mm at 2 years (P = 0.013) while the mean JSW of the MAC increased from 1.89 (±0.51) mm to 2.87 (±0.44) mm (P = 0.006), as shown in Figure 3.
(Note: The minimum and mean JSW changes are correct in the table and figure, but the numbers in the text are not correct for the KJDTKA group.)
Tables and Figure
Amended versions of Table 2 , Table 3 , and Figure 1 are included. In both tables, changes were made to the WOMAC, VAS pain, and ICOAP parameters, as indicated in italics. In Figure 1 , the most important changes are seen in 1B and 1D, including a change in P values for differences between groups, which in the case of KJD versus TKA is now significant.
On behalf of all authors,
Sincerely,
Mylène Jansen and Floris Lafeber
Reference
- 1. Jansen MP, Besselink NJ, van Heerwaarden RJ, Custers RJH, Emans PJ, Spruijt S. et al. Knee joint distraction compared with high tibial osteotomy and total knee arthroplasty: two-year clinical, radiographic, and biochemical marker outcomes of two randomized controlled trials. Cartilage. Published online February 13, 2019. doi: 10.1177/1947603519828432 [DOI] [PMC free article] [PubMed] [Google Scholar]