2018 年 65 巻 10 号 p. 991-999
Acromegalic arthropathy is a common complication of acromegaly and harms the quality of life of the patients even after acromegaly is in long-term remission. A recent study demonstrated by knee MRI the characteristic structural features of acromegalic arthropathy. However, the effects of treatment for acromegaly on such structural features are almost unknown. This study was undertaken to analyze the effects of transsphenoidal surgery (TSS) on acromegalic arthropathy and elucidate whether knee MRI findings are reversible or irreversible. We analyzed 22 patients with acromegaly (63.7% females, median age 58 years) by knee MRI at diagnosis. Out of these 22 patients, 16 who underwent TSS (68.9% female, median age 58 years) were also subjected to knee MRI 2 months after TSS. As for X-ray undetectable findings, MRI detected synovial thickening, bone marrow lesion, ligament injury and meniscus injury in 22.7%, 22.7%, 4.7% and 59.1% of the patients, respectively. With respect to the 16 patients who underwent TSS, clinical and structural improvements were observed respectively in 100%, 66.7% and 66.7% of the patients who showed knee joint pain, synovial thickening and bone marrow lesion before TSS. However, no patient showed structural improvement of meniscus injury after TSS. In acromegalic arthropathy, synovial thickening and bone marrow lesions are reversible while meniscus injury is irreversible. Because all those findings are associated with the exacerbation of arthropathy, they may be therapeutic targets for preventing the progression of arthropathy by endocrinological and orthopedic intervention.
ACROMEGALY is a chronic disorder due to the overproduction of growth hormone (GH) and resultant persistent elevation in the concentration of insulin-like growth factor-1 (IGF1), also called somatomedin-C, mainly because of pituitary adenoma [1]. Patients with acromegaly demonstrate higher mortality and morbidity such as malignant and benign neoplasms, sleep apnea syndrome (SAS), hypertension, diabetes mellitus and heart failure [1]. A certain number of patients with acromegaly also suffer from secondary osteoarthropathy (OA) that is termed as acromegalic arthropathy [2]. Acromegalic arthropathy has been regarded as one of the most frequent complications of acromegaly [3, 4] and 70% of patients with active acromegaly have joint complications at diagnosis. Those joint-related complications are also observed in more than 70% of patients with acromegaly and they impair physiologically and psychologically the quality of life (QOL) of those patients even if the disease is in long-term complete remission [3, 5]. Therefore, acromegalic arthropathy has been considered as an irreversible complication although the early stage of the disease is sometimes thought to be reversible by appropriate therapies [6]. Excessive GH-IGF1 signal is considered to be the major pathogenic and aggregative factor for acromegalic arthropathy [7, 8], however, the precise pathophysiological evidences remain to be elucidated.
So far, the pathological image of acromegalic arthropathy has been evaluated mainly with knee X-ray [3, 7, 9]. Osteophytosis and joint space widening has been thought to be the characteristic features of acromegalic arthropathy [9]. Joint space widening indicating periarticular hypertrophy has sometimes been regarded as a feature of the early stage of the disease and has been associated with reversibility of joint complications [3]. On the other hand, osteophytosis and joint space narrowing has been regarded as features of the chronic stage of the disease due to persistent excess of GH-IGF1 [3]. Recently, there was a study in which joint complications of acromegaly were evaluated by knee magnetic resonance imaging (MRI) to further characterize the structural features of acromegalic arthropathy compared with primary OA [10]. In that study, 10 patients with active acromegaly, 16 patients in biological remission of acromegaly and 25 patients with primary OA were included. Compared to the patients with primary OA, higher prevalence of cartilage thickness and lower prevalence of subchondral cysts and bone marrow lesions were observed in those with acromegaly [10]. The study also demonstrated that cartilage thickness was more apparent in the patients with active acromegaly than those in remission [10]. Although that study has contributed greatly to the knowledge about the structural features of acromegalic arthropathy, additional MRI data are necessary for further understanding the pathophysiology of the disease. Moreover, a comparison of knee MRI findings before and after transsphenoidal surgery (TSS) in the same patients will also contribute to classify the “reversible” and “irreversible” features of acromegalic arthropathy. Here, we report a structural characterization of knee MRI findings in 22 patients with acromegaly. We also evaluated 16 patients who underwent TSS and compared knee MRI findings before and after surgery to clarify additional characteristics of knee MRI findings in patients with acromegaly for further understanding of the pathology of acromegalic arthropathy.
This was a retrospective single-center study. We recruited 22 patients with acromegaly. The patients were entered into the study from February 2010 to October 2016. All the patients fulfilled the criteria of acromegaly established by the Japanese Endocrine Society. Study subjects were identified through the endocrine unit of Tohoku University Hospital and through 7 endocrinologists in private practice. In all patients, knee MRI was performed at diagnosis. When the patients were confirmed as candidates for surgery, knee MRI was also performed at the postoperative hormonal evaluation of acromegaly. The ethics committee of Tohoku University School of Medicine approved this protocol, which was consistent with the principles of the Declaration of Helsinki and Title 45, US Code of Federal Regulations, Part 46, Protection of Human Subjects.
Knee MRIThe knee MRI images were evaluated with gadolinium-enhanced fat-saturated techniques by a radiologist belonging to Tohoku University Hospital. Because one patient had severe chronic kidney disease, spectral pre-saturation with inversion recovery (SPIR) imaging was selected (Case 14). As MRI findings, synovial thickenings and bone marrow lesions were defined by the contrast enhancement of synovial membrane detected with gadolinium-enhanced MRI and by the high-signal lesions in bone marrows detected with fat-saturated MRI, respectively.
Evaluation of the complications of acromegalyThe history of knee joint pain, diabetes mellitus, hypertension, SAS and benign and malignant neoplasms were evaluated. Knee joint pain was assessed by medical interview and physical examination. History of diabetes mellitus was defined based on medication with antidiabetic drugs or elevated serum level of HbA1c (>6.5%). History of hypertension was defined from use of antihypertensive drugs. History of SAS was defined by abnormal results of a screening test performed using a screening device (APNOMONITOR, CHEST Medical Instruments Inc, Tokyo, Japan) or continuous positive airway pressure (CPAP) for SAS. History of benign and malignant neoplasms was defined from their medical history and systemic screening with ultrasound and computed tomography (CT).
Biological testsSerum IGF1 level was measured by immunoradiometric assay (FUJIREBIO Inc, Tokyo). Standard deviation (SD) scores of IGF1 according to age and sex were also calculated [11] using a specific web tool for Japanese patients (http://ghw.pfizer.co.jp/adult/information/igf-i/index.html). Serum GH level was measured by electrochemiluminescence immunoassay (Roche Diagnostics, Tokyo). Serum concentration of HbA1c was measured by standard procedures.
Statistical analysisData are expressed as the median value followed by the first and third quartiles in parentheses. GraphPad Prism 6 (MDF Co Ltd, Tokyo) was used for statistical analysis. Wilcoxon matched-pairs signed rank test was used for comparison of pre- and post-surgical parameters, while Mann-Whitney test and chi-squared test were used to compare clinical characteristics between patients with and without knee joint pain. The level of statistical significance was set at p < 0.05
Among the 22 patients with acromegaly included in this study, 11 (50%) suffered from knee joint pain. Other clinical characteristics of the patients are shown in Table 1. There were no differences between the patients with and without knee joint pain (Supplementary Table 1). Joint space narrowing and osteophytosis, which are detectable by knee X-ray, were also detected in 12 (54.5%) and 15 (68.2%) patients, respectively, by knee MRI (Fig. 1a). We also found that synovial thickening, bone marrow lesion, ligament injury and meniscus injury, which are undetectable by knee X-ray, were observed in 5 (22.7%), 5 (22.7%), 1 (4.5%) and 13 (59.1%) of 22 patients, respectively (blue bars in Fig. 1). Especially, among the patients in whom synovial thickening, bone marrow lesion and meniscus injury were observed by MRI, knee joint pain occurred in 4 of 5 (80%), 5 of 5 (100%), and 6 of 13 (46.2%) patients, respectively (yellow bars in Fig. 1). Since joint space narrowing and osteophytosis are irreversible and observed at the later stage of acromegalic arthropathy, we thought that existence of those findings might predict pathological stages of acromegalic arthropathy. Therefore, we compare the frequency of those findings between the patients with or without knee joint pain. Joint space narrowing was observed in 7 (63.6%) and 5 (45.5%) patients of each 11 patient with and without knee joint pain, respectively. And osteophytosis was observed in 6 (54.5%) and 9 (81.8%) patients of each 11 patient with and without knee joint pain, respectively. And the number of patients who did not show both joint space narrowing and osteophytois was 2 (8%) and 2 (8%) in each 11 patient with and without knee joint pain. Those data showed that, in this study, the duration of acromegalic arthtopathy was not different between patients with and without knee joint pain (Supplemental Table 1).
| n | 22 |
| Gender Males/Females (%) | 8/14 (36.3/63.7) |
| Age, years | 58 (50–65) |
| Body mass index (kg/m2) | 25.2 (23.6–27.4) |
| Knee joint pain, % | 50.0 |
| Diabetes mellitus, % | 22.7 |
| HbA1c, % | 6.0 (5.7–6.2) |
| History of malignant neoplasm, % | 4.5 |
| History of benign neoplasm, % | 86.4 |
| Sleep apnea syndrome, % | 68.2 |
| Hypertension, % | 59.1 |
| IGF1, ng/mL | 521.0 (449.5–757.5) |
| IGF1, SD | 6.3 (5.5–7.9) |
| Nadir GH for 75 g OGTT, ng/mL | 5.8 (3.3–17.2) |
Data are median (first and third quartiles) values.
Abbreviation: OGTT, oral glucose tolerance test; SD, standard deviation.
| Knee joint pain (–) | Knee joint pain (+) | p value | |
|---|---|---|---|
| n | 11 | 11 | 1.00 |
| Gender Males/Females (%) | 4/7 (36.3/63.7) | 4/7 (36.3/63.7) | 1.00 |
| Age, years | 64 (48–65) | 56 (48–60) | 0.30 |
| Body mass index (kg/m2) | 25.4 (23.3–28.8) | 24.4 (23.7–25.3) | 0.43 |
| Diabetes, % | 18 | 27 | 0.61 |
| HbA1c, % | 5.8 (5.7–6.1) | 6.0 (5.8–6.3) | 0.39 |
| Malignant neplasm, % | 0 | 9.1 | 0.30 |
| Benign neoplasm, % | 90.9 | 81.8 | 0.53 |
| Sleep apnea syndrome, % | 63.6 | 72.7 | 0.65 |
| Hypertension, % | 63.6 | 54.5 | 0.66 |
| IGF1, ng/mL | 513.0 (436.4–661.0) | 574.0 (428.5–826.0) | 0.93 |
| IGF1, SD | 5.3 (6.2–6.8) | 6.4 (5.3–8.6) | 0.73 |
| Joint space narrowing (%) | 45 | 63 | 0.39 |
| Osteophytosis (%) | 81 | 54 | 0.16 |
| Nadir GH for 75 g OGTT, ng/mL | 5.8 (3.8–13.7) | 6.6 (4.3–32.4) | 0.59 |
Data are median (first and third quartiles) values.
Knee MRI findings from the 22 patients with acromegaly
Data on each blue and yellow bar represented the percentage of the patients whose knee MRI findings were positive and the percentage of whom with knee joint pain in those having each knee MRI finding, respectively in all 22 patients with acromegaly. The MRI findings are divided from 2 groups, the X-ray detectable group and the X-ray undetectable group. The numbers above and inside the parentheses indicate the percentage and the number of patients, respectively. Abbreviation: MRI, magnetic resonance imaging.
TSS was performed for 16 of the 22 patients with acromegaly. As shown in Table 2, the median age was 58 years (51.8–64.3 years) and 11 patients (68.9%) were females. The median presurgical and postsurgical IGF1 values were 6.8 SD (5.8–8.3 SD) and 2.6 (1.9–3.5 SD), respectively. The median presurgical and postsurgical BMI were 25.2 kg/m2 (23.3–28.2 kg/m2) and 24.6 (21.9–26.6 kg/m2), respectively. The median reduction of SD scores of IGF1 and BMI were 65.3% (42.1–74.9%, p < 0.0001) and 4.4% (2.5–6.2%, p < 0.0001), respectively (Table 2). To clarify the effects of the amelioration of GH-IGF1 signals on the knee joints, postsurgical knee MRI was performed for all 16 patients at about 7.5 weeks (median, 6–10 weeks) after TSS. All of the 7 patients who complained about knee joint pain showed improvement after TSS (Fig. 2). With regard to joint space narrowing and osteophytosis, MRI showed no structural changes after TSS in any of the patients even though knee joint pain had ameliorated (Supplementary Table 2). With respect to bone marrow lesion, MRI showed a decrease in size in 2 of 3 (66.7%) and a slight increase in 1 of 3 (33.3%) patients after TSS. The signal intensity of synovial thickening decreased in 2 of 3 (66.7%) and remained unchanged in 1 of 3 (33.3%) patients after surgery. On the other hand, meniscus injury showed no structural change after TSS. Representative images of signal changes of synovial thickening and bone marrow lesion by TSS are shown in Fig. 3. The two cases of improved synovial thickening and the two cases with reduction of the bone marrow lesion, these structural changes seemed to be associated with the amelioration of knee joint pain (Table 3), but meniscus injury did not show any association with knee joint pain (Supplementary Table 2).
| Age | Sex | Weeks after TSS |
IGF1 (ng/mL) | IGF1(SD) | Nadir GH (ng/mL) | BMI (kg/m2) | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Pre | Post | Pre | Post | Pre | Post | Pre | Post | ||||
| Case 1 | 25 | F | 7 | 869 | 357 | 5.8 | 2.0 | 21.4 | 2.3 | 29.2 | 26.5 |
| Case 2 | 32 | M | 10 | 1,190 | 257 | 12.4 | 1.4 | 40.3 | 0.1 | 28.0 | 27.4 |
| Case 3 | 49 | M | 12 | 902 | 270 | 9.1 | 2.4 | 62.4 | 0.2 | 24.0 | 23.5 |
| Case 4 | 51 | M | 10 | 562 | 335 | 6.2 | 3.5 | 10.1 | 8.1 | 29.4 | 28.7 |
| Case 5 | 52 | F | 8 | 418 | 164 | 5.2 | 0.9 | 5.0 | 1.8 | 23.6 | 22.0 |
| Case 6 | 55 | F | 11 | 504 | 244 | 6.1 | 2.7 | 5.5 | 0.1 | 19.1 | 18.4 |
| Case 7 | 56 | F | 7 | 1,029 | 292 | 10.0 | 3.5 | 8.1 | 1.6 | 23.8 | 22.4 |
| Case 8 | 57 | M | 6 | 795 | 295 | 8.3 | 3.0 | 21.2 | 2.0 | 22.6 | 21.5 |
| Case 9 | 59 | F | 6 | 439 | 382 | 5.4 | 4.8 | 1.4 | 0.9 | 27.5 | 26.8 |
| Case 10 | 59 | F | 10 | 652 | 387 | 7.7 | 4.8 | 49.8 | 6.0 | 25.2 | 24.2 |
| Case 11 | 60 | F | 6 | 750 | 730 | 8.1 | 8.0 | 4.2 | 3.8 | 21.9 | 20.6 |
| Case 12 | 64 | F | 7 | 760 | 192 | 8.3 | 2.0 | 3.3 | 0.1 | 37.8 | 35.8 |
| Case 13 | 65 | F | 6 | 443 | 134 | 5.7 | 0.7 | 5.8 | 0.1 | 25.4 | 25.1 |
| Case 14 | 65 | F | 8 | 500 | 171 | 6.3 | 1.6 | 1.3 | 0.1 | 22.5 | 21.0 |
| Case 15 | 72 | M | 9 | 311 | 272 | 4.3 | 3.6 | 1.5 | 0.7 | 25.2 | 25.0 |
| Case 16 | 74 | F | 6 | 529 | 169 | 7.2 | 2.1 | 17.2 | 0.6 | 28.4 | 26.5 |
Pre, presurgical data; Post, postsurgical data.
Post surgical data were collected at the weeks after TSS represented in this table (“Weeks after TSS”).
Abbreviations: TSS, transsphenoidal surgery; M, male; F, female; SD, standard deviation; BMI, body mass index
The percentages of the improvement of knee joint pain and reduction of signal intensity and size of MRI findings
Data on each bar represents the percentage of the patients with acromegaly whose presurgical clinical symptom and MRI findings were improved after TSS. The number above and inside the parentheses indicate the percentage and the number of patients whose symptom and MRI findings were improved after TSS per the number of patients who had each symptom and MRI finding before TSS, respectively. Because there was no patient with ligament injury in the 16 cases that undertook TSS, no data was shown about the ligament injury. Abbreviations: TSS, transsphenoidal surgery; MRI, magnetic resonance imaging; ND, no data.
| Age | Sex | Knee joint pain | Joint space narrowing | Osteophytosis | Meniscus injury | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pre | Post | Pre | Post | Pre | Post | Pre | Post | |||
| Case 1 | 25 | F | – | – | – | – | – | – | – | – |
| Case 2 | 32 | M | + | Improved | – | – | + | Unchanged | – | – |
| Case 3 | 49 | M | + | Improved | + | Unchanged | + | Unchanged | + | Unchanged |
| Case 4 | 51 | M | – | – | – | – | + | Unchanged | + | Unchanged |
| Case 5 | 52 | F | + | Improved | – | – | – | – | – | – |
| Case 6 | 55 | F | – | – | + | Unchanged | + | Unchanged | + | Unchanged |
| Case 7 | 56 | F | + | Improved | + | Unchanged | – | – | + | Unchanged |
| Case 8 | 57 | M | – | – | – | – | + | Unchanged | – | – |
| Case 9 | 59 | F | + | Improved | + | Unchanged | – | – | – | – |
| Case 10 | 59 | F | + | Improved | + | Unchanged | + | Unchanged | + | Unchanged |
| Case 11 | 60 | F | + | Improved | + | Unchanged | + | Unchanged | + | Unchanged |
| Case 12 | 64 | F | – | – | + | Unchanged | + | Unchanged | + | Unchanged |
| Case 13 | 65 | F | – | – | + | Unchanged | + | Unchanged | + | Unchanged |
| Case 14 | 65 | F | – | – | – | – | + | Unchanged | + | Unchanged |
| Case 15 | 72 | M | – | – | + | Unchanged | + | Unchanged | + | Unchanged |
| Case 16 | 74 | F | – | – | + | Unchanged | + | Unchanged | + | Unchanged |
Pre, presurgical data; Post, postsurgical change.
Abbreviations: MRI, magnetic resonance imaging; TSS, transsphenoidal surgery; M, male; F, female; ND, no data; +, positive; –, negative.
Representative images of synovial thickening and bone marrow lesion in knee MRI of patients with acromegaly before and after MRI
Gadolinium-enhanced fat-saturated MRI revealed synovial thickening (upper, Case 9 from Table 2) and bone marrow lesion (bottom, Case 7 from Table 2). Compared with those MRI findings before TSS (left), the signal intensities were decreased about 2 month after TSS (right). Abbreviations: TSS, transsphenoidal surgery; MRI, magnetic resonance imaging.
| Age | Sex | Knee joint pain | Synovial thickening | Bone marrow lesion | ||||
|---|---|---|---|---|---|---|---|---|
| Pre | Post | Pre | Post | Pre | Post | |||
| Case 1 | 25 | F | – | – | – | – | – | – |
| Case 2* | 32 | M | + | Improved | + | Reduced | – | – |
| Case 3 | 49 | M | + | Improved | – | – | – | – |
| Case 4 | 51 | M | – | – | – | – | – | – |
| Case 5 | 52 | F | + | Improved | – | – | – | – |
| Case 6 | 55 | F | – | – | – | – | – | – |
| Case 7* | 56 | F | + | Improved | + | Reduced | + | Increased |
| Case 8 | 57 | M | – | – | – | – | – | – |
| Case 9* | 59 | F | + | Improved | – | – | + | Reduced |
| Case 10* | 59 | F | + | Improved | + | Unchanged | + | Reduced |
| Case 11 | 60 | F | + | Improved | – | – | – | – |
| Case 12 | 64 | F | – | – | – | – | – | – |
| Case 13 | 65 | F | – | – | – | – | – | – |
| Case 14 | 65 | F | – | – | – | – | – | – |
| Case 15 | 72 | M | – | – | – | – | – | – |
| Case 16 | 74 | F | – | – | – | – | – | – |
Pre, presurgical data; Post, postsurgical change.
Abbreviations: MRI, magnetic resonance imaging; TSS, transsphenoidal surgery; M, male; F, female; ND, no data; +, positive; –, negative.
* indicated the cases which both of knee joint pain and knee MRI findings were ameliorated after knee MRI.
Because there have been few patients with acromegalic arthropathy evaluated using MRI, although a recent study has firstly demonstrated the characteristics of knee MRI findings [10], we considered further analysis of those findings was important to examine the effects of TSS [10]. In this observational study, we evaluated knee MRI findings from patients with acromegaly and found 2 novel facts.
First, we found that about 25% of our patients with acromegaly showed synovial thickening and bone marrow lesion on knee MRI and some of those abnormal MRI findings tended to shrink along with the improvement of knee joint pain at about 2 months after TSS. The occurrence of bone marrow lesion was consistent with the observations of a previous study [10], but that of synovial thickening has not been reported previously. Synovial thickening corresponds to a mild chronic synovial inflammation termed as synovitis [12]. In primary knee OA, synovitis is strongly associated with cartilage damage and bone marrow lesion [13] and the immune reaction induced by the cartilage or subchondral breakdown products [14] has been regarded as one of the major pathological mechanisms of synovial inflammation. Synovial inflammation causes further destruction of the articular cartilage resulting in the progression of osteoarthritis [15]. Bone marrow lesions have also been shown to be strongly associated with joint pain and synovitis [16]. Bone marrow lesions of the knee can be caused by multiple pathologies that are mainly classified into traumatic or non-traumatic and reversible or irreversible [17]. Bone marrow lesions associated with primary OA are generally non-traumatic and reversible [17]. Bone marrow lesions in primary OA occur where the articular cartilage is defective [18] and are considered to induce knee joint pain through stimulation of the periosteal nerve fibers via cellular mediators derived from necrotic tissue, trabecular microfractures and pressure [19]. Bone marrow lesions are also regarded as a prognostic factor for the progression of primary OA [20]. Those previous reports indicated that synovial thickening and bone marrow lesions might be closely associated with the exacerbation of osteoarthritis. With respect to patients with acromegaly, excessive GH-IGF1 signal is considered to affect the homeostasis of bone and cartilage tissue [3, 21]. Moreover, the fact that the frequency of bone marrow lesions in acromegalic arthropathy is lesser than that in primary OA indicates that specific pathological mechanisms may be involved in acromegalic arthropathy. Therefore, our findings that synovial thickening and bone marrow lesions ameliorated after TSS indicate that excessive GH-IGF1 signal may affect the pathogenesis and progression of synovial thickening and bone marrow lesions in patients with acromegaly. Although bone marrow lesions are less frequently observed in patients with acromegalic arthropathy than in those with primary OA [10] and the frequency of synovial thickening in those 2 types of arthropathy has not been compared, our data suggest an improvement of excessive GH-IGF1 signal through appropriate therapy is important for ameliorating synovitis and bone marrow lesion, and thereby prevent the progression of acromegalic arthropathy, which has been considered to be irreversible despite biochemical control of acromegaly itself.
Second, we also detected on MRIs a meniscus injury in more than half of our patients with acromegaly and that injury remained unchanged 2 months after TSS, the same as joint space narrowing and osteophytosis. Meniscus injury is a common feature in middle-aged and elderly people in the general population and in most of them it does not cause knee joint pain [22]. However, meniscus injury has also been considered an aggravating factor for osteoarthritis which causes persistent knee joint pain [23]. Therefore, the existence of meniscus injury with no improvement on MRI may be one reason why acromegalic arthropathy is irreversible and harms the quality of life of patients even after GH-IGF1 signal is improved by appropriate therapy [5]. Usually, the first treatment for asymptomatic meniscus injury is conservative/non-operative management such as weight reduction, rehabilitation or physical exercise [22, 23]. On the other hand, severe and prolonged meniscus injury causing knee joint pain will sometimes require surgical treatment [22, 23]. Those facts also remind us that assessment with knee MRI should be actively considered for patients with acromegaly who are suffering from persistent knee joint pain; besides, appropriate therapies, including surgery, should be employed for arthropathy even after successful treatment for acromegaly.
This study has various limitations: 1) the number of patients was too small to draw definite conclusions, 2) the interval to assess biological control after TSS was too short, 3) the follow-up data gathered for the analysis of knee MRI after TSS was not enough, 4) the approach of fat-suppression analysis of MRI differed among patients, 5) the lack of data concerning long outcome of arthropathy and 6) the lack of clear diagnostic criteria to differentiate acromegalic arthropthy and primary OA, are the major limitations of this study. Because the recent clinical guideline for acromegaly [1] recommends that postoperative testing should be evaluated at 12 weeks or later, a follow-up period for performing postoperative knee MRI might also be appropriate at the same period for biological evaluations.
In conclusion, we analyzed knee MRI in the patients with acromegaly and found that knee MRI could detect synovial thickening and bone marrow lesions that are potential aggravating factors for osteoarthropathy, and that those findings ameliorated along with the improvement of GH-IGF1 signal by TSS. Knee MRI could also detect meniscus injury that is also an aggravating factor for osteoarthropathy but it was not affected by TSS. Those facts contribute to the understanding of “reversible” and “irreversible” findings of acromegalic arthropathy and indicate that it is necessary to reconsider an appropriate assessment of treatment, including surgical approach for acromegalic arthropathy.
We thank Ms. Yasuko Tsukada and Ms. Akane Sugawara (Tohoku University) for technical support and secretarial assistance.
The authors declare that they have no conflicts of interest to disclose.
M.N., M.K., and R.M. designed this study. M.N., M.K., and F.S. wrote the manuscript. M.N., M.K., R.M., Y.O., K.O., Y.T., and Y.I. examined each patient and acquired the data. M.H. analyzed radiological examination by MRI. K.T., S.I., and F.S. supervised this project.
