Acetabular Cysts Research Articles

A modified non-contrast MRI in the preoperative examination of periacetabular osteotomy at 3.0T

PurposeTo investigate whether the modified hip non-contrast magnetic resonance imaging (MRI) can replace the direct MRI hip arthrography (d-MRA) at 3.0T in developmental dysplasia of the hip (DDH) patients undergoing periacetabular osteotomy (PAO) preoperative examination, and also to assess the difference between these two methods.Materials and methodsThis retrospective study involved 35 patients (38 hips) with DDH who underwent periacetabular osteotomy, age 9–41 years old (mean age 25), 4 males (4 hips) and 34 females (34 hips). Each patient underwent both d-MRA and modified 3.0T non-contrast MRI examination of the hip joint. All patients underwent hip-preserving PAO surgery subsequently. Statistical analyses were performed to compare the joint injury examined by the two imaging methods.ResultsThe modified non-contrast MRI detected the labral injury with a sensitivity of 94%, a specificity of 75%, an accuracy of 92%, and a positive predictive value of 97%. Among the 38 hips, 10 hips had labral varus (i.e., inward deviation or angulation of the acetabular labrum) with an incidence rate of 26% (10/38), 9 hips had acetabular cysts (i.e., the fluid-filled sacs that develop in or around the acetabulum, the socket of the hip joint) with an incidence rate of 23% (9/38). One patient had both the labral cyst and acetabular cartilage injury, and two patients had labral cyst only (overall incidence rate of labral cyst 7% (3/38)). The results were comparable to those of d-MRA in the examination of cartilage injury, labral varus, acetabular cyst, and labral cyst.ConclusionFor preoperative hip-preserving surgery in DDH patients, the modified non-contrast MRI performed similarly to the d-MRA at 3.0T in diagnostic capabilities. The labral injury mostly occurs in the anterior upper quadrant.

Arthroscopic Bone Grafting of Deep Acetabular Cysts in Hip Preservation Surgery: A Matched Case-Control Study.

Acetabular subchondral cysts are commonly identified signs of joint degeneration and arthritis. This pathology is generally considered a relative contraindication for hip preservation surgery. To investigate the effect of arthroscopic bone grafting for the treatment of acetabular subchondral cysts. Cohort study (diagnosis); Level of evidence, 3. We completed a retrospective analysis of hip arthroscopies performed by the senior author between 2013 and 2021. Patients with radiologic evidence of acetabular cysts who underwent arthroscopic bone grafting, with or without subsequent periacetabular osteotomy (PAO) and/or derotational femoral osteotomy with a minimum of 2-year follow-up, were included in the analysis. Patients undergoing surgical treatment for diagnoses of slipped capital femoral epiphysis, Legg-Calves-Perthe disease, osteochondromatosis, or postdislocation syndrome, as well as patients who refused to participate in the study, were excluded. We compared the patient-reported outcomes (PROs) for patients who underwent arthroscopic bone grafting with a case-matched control group without acetabular cysts with the same surgical route (hip arthroscopy or hip arthroscopy followed by PAO). An "inside-out" arthroscopic bone grafting technique was utilized, which allowed for precise access to the cystic cavity through the articular side. We analyzed postoperative PROs at a minimum of 2 years postoperatively using the international Hip Outcome Tool (iHOT-12) and Nonarthritic Hip Score (NAHS). In total, there were 44 hips in the experimental group and 78 hips in the control group. The mean PRO interval in the experimental group was 3.4 years (range, 2-5 years postoperatively), with 20 patients reaching PROs 5 years postoperatively. The experimental group reported significant improvement of iHOT-12 and NAHS scores postoperatively (both P < .001). Postoperative iHOT-12 and NAHS scores did not significantly differ between groups over a 5-year follow-up interval (P = .26 and .17, respectively). Radiographic evidence of cyst healing was achieved in all 7 patients who underwent postoperative magnetic resonance imaging, with 3 cases of complete resolution. Acetabular subchondral cysts treated with an inside-out method of arthroscopic bone grafting in the setting of hip preservation surgery with or without PAO was associated with a significant improvement in midterm PROs, comparable with a control group of patients without acetabular cysts who did not undergo bone grafting. Our results support the use of arthroscopic grafting in appropriately selected patients and suggest that hip preservation is not contraindicated in patients with acetabular subchondral cysts.

Are degenerative findings detected on traction MR arthrography of the hip associated with failure of arthroscopic femoroacetabular impingement surgery?

ObjectivesTo identify preoperative degenerative features on traction MR arthrography associated with failure after arthroscopic femoroacetabular impingement (FAI) surgery.MethodsRetrospective study including 102 patients (107 hips) undergoing traction magnetic resonance arthrography (MRA) of the hip at 1.5 T and subsequent hip arthroscopic FAI surgery performed (01/2016 to 02/2020) with complete follow-up. Clinical outcomes were assessed using the International Hip Outcome Tool (iHOT-12) score. Clinical endpoint for failure was defined as an iHOT-12 of < 60 points or conversion to total hip arthroplasty. MR images were assessed by two radiologists for presence of 9 degenerative lesions including osseous, chondrolabral/ligamentum teres lesions. Uni- and multivariate Cox regression analysis was performed to assess the association between MRI findings and failure of FAI surgery.ResultsOf the 107 hips, 27 hips (25%) met at least one endpoint at a mean 3.7 ± 0.9 years follow-up. Osteophytic changes of femur or acetabulum (hazard ratio [HR] 2.5–5.0), acetabular cysts (HR 3.4) and extensive cartilage (HR 5.1) and labral damage (HR 5.5) > 2 h on the clockface were univariate risk factors (all p < 0.05) for failure. Three risk factors for failure were identified in multivariate analysis: Acetabular cartilage damage > 2 h on the clockface (HR 3.2, p = 0.01), central femoral osteophyte (HR 3.1, p = 0.02), and femoral cartilage damage with ligamentum teres damage (HR 3.0, p = 0.04).ConclusionJoint damage detected by preoperative traction MRA is associated with failure 4 years following arthroscopic FAI surgery and yields promise in preoperative risk stratification.Clinical relevance statementEvaluation of negative predictors on preoperative traction MR arthrography holds the potential to improve risk stratification based on the already present joint degeneration ahead of FAI surgery.Key Points• Osteophytes, acetabular cysts, and extensive chondrolabral damage are risk factors for failure of FAI surgery.• Extensive acetabular cartilage damage, central femoral osteophytes, and combined femoral cartilage and ligamentum teres damage represent independent negative predictors.• Survival rates following hip arthroscopy progressively decrease with increasing prevalence of these three degenerative findings.Graphical

Arthroscopic Bone and Cartilage Grafting of Acetabular Cysts With Autologous Tissue

Repair of acetabular cysts and cartilage defects presents a challenge for the hip-preservation surgeon. Currently, most techniques involve allograft sources or open surgery. We present an arthroscopic technique using autologous graft sources for both bone and cartilage to repair subchondral acetabular cysts and the overlying cartilage defect. This technique uses new technology in combination with familiar arthroscopic instruments to decrease morbidity, hasten rehabilitation, and possibly improve the prognosis of these difficult to treat lesions.

Factors Associated with Failure following Hip Arthroscopy for FAI in Patients over 40

Hip arthroscopy is considered one option in preserving the hip. Previous studies have shown age may be a predictor of failure; however, it is unclear what factors lead to failure in older patient. The purpose of this study was to determine factors associated with conversion to total hip arthroplasty in patient over 40 undergoing hip arthroscopy. 268 patients were identified who were over 40 years of age, had primary hip arthroscopy for FAI with labral repair. All had minimum joint space of >2mm. There were 144 females and124 males, with an average age of 49±6. Hips were evaluated using the modified Harris hip score(mHHS), Hip Outcome Score (HOS), WOMAC and patient satisfaction (1 to 10; 10=very satisfied). Conversion to THA was confirmed by patients. 87 patients underwent THA. Patients who converted to THA were significantly older (50 vs 48;p=0.001), higher Tonnis angle (10.7 vs 6.8;p=0.016), lower lateral center edge (34 vs 37;p=0.044), larger alpha angle (77 vs 70;p=0.028). The following preoperative subjective complaints were associated with THA: stiffness interfering with activity were 3.7 [95%CI, 2-7] time more likely to convert to THA(p<0.001); weakness were 2.7[95%CI,1.5-5] times more likely to convert to THA(p=0.001) and loss of motion were 1.9{95%CI,1.1 to 3.2] times more likely to convert to THA. At arthroscopy, the presence of femoral cyst was not associated with THR, but patients with an acetabular cyst were 3.0 [95%CI,1.6-5.4] times more likely to convert to THA. Patients with microfracture were 10 [95%CI, 6-18] times more likely to convert to THR. Using regression analysis, preoperative weakness, microfracture, and acetabular cyst were independent predictors of THA (p<0.001, R2=0.408). Of the patients who did not have THA, at an average 7-year follow-up (5 to 11 years), the mean SF-12 PCS was 51.7±9, and mHHS was 85±17, HOS ADL was 89±15. The median WOMAC was 5 [95%CI 8.7-12.9] and median patient satisfaction with outcome was 10 [95%CI 8-9]. HOS-ADL PASS was achieved in 75% of patients. Factors associated with THR following arthroscopy in patients over 40 include age, symptoms of weakness, stiffness, and loss of motion, and microfracture and acetabular cysts at arthroscopy. Those patients who do not require THR, have excellent outcomes and high patient satisfaction.

Surgical Treatment of Subchondral Bone Cysts of the Acetabulum With Calcium Phosphate Bone Substitute Material in Patients Without Advanced Arthritic Hips

Subchondral acetabular edema and cysts, as a consequence of degenerative changes of the hip, are associated with disability, pain, and worsened function in this joint. The arthroscopic treatment of intra-articular pathologies, such as femoroacetabular impingement syndrome and labral tears, when associated with those alterations, has been suggested to provide inferior outcomes to those in patients without subchondral changes. Yet, the direct treatment of subchondral pathology has been limited. Recently, a technique for insufflating bone substitute into the bone marrow lesions of the knee, Subchondroplasty (Zimmer Knee Creations, Exton, PA), has led to promising results. Subchondroplasty has raised attention as a possible minimally invasive procedure to treat cystic changes in the acetabulum in patients who are not yet candidates for hip replacement. We present the technique of acetabular Subchondroplasty, in which a bone substitute material is injected into subchondral acetabular cysts under fluoroscopic guidance. In this technique, hip arthroscopy is used in conjunction with fluoroscopic guidance to address intra-articular pathologies and assess for possible intra-articular extravasation of the injectable material.

Acetabular Labral Tears Are Common in Asymptomatic Contralateral Hips With Femoroacetabular Impingement.

The number of patients undergoing hip arthroscopy for labral tears has increased, but labral tears are sometimes seen in asymptomatic patients with femoroacetabular impingement (FAI). The frequency of this finding, however, has not been well characterized nor is the proportion of patients with previously asymptomatic labral tears who may later become symptomatic. The purpose of this study was to determine (1) the prevalence of labral tears and other intraarticular pathology in the asymptomatic contralateral hip of patients undergoing surgery for symptomatic FAI; (2) the likelihood that the asymptomatic hip had become symptomatic at latest followup; and (3) any association between MRI findings and age, sex, and body mass index (BMI) in both symptomatic and asymptomatic sides. This study included patients who were diagnosed with unilateral symptomatic FAI between 2013 and 2015 and who had an available MRI of both hips. The study included 100 patients (47 females, 53 males) with a mean age of 33 years (range, 17-57 years). Patients with a symptomatic contralateral hip (n = 56) or an unsuitable MRI for review based on both reviewers' consensus (n = 344) were excluded. The MRI of both hips was independently evaluated by two orthopaedic surgeons and interobserver reliability tested. The interobserver reliability for the two surgeons' MRI ratings was almost perfect (κ ≥ 0.85). The presence of a labral tear, an acetabular chondral lesion, subchondral acetabular cysts, and fibrocystic changes in the femoral head-neck junction was documented for both hips. At latest followup, asymptomatic hips were investigated for any symptomatic labral tears or surgical procedures resulting from FAI. A labral tear was recorded in 97 (97%) and 96 (96%) of symptomatic hips, respectively, for each surgeon's evaluation. A labral tear was also detected in 41 (41%) and 43 (43%) of asymptomatic hips. In addition, an acetabular chondral lesion was detected in 32 (32%) and 35 (35%) of the symptomatic hips and 15 (15%) and 17 (17%) of the asymptomatic hips. At latest followup, nine of the patients were diagnosed with symptomatic labral tears in the contralateral asymptomatic hip and were treated. None of the radiologic parameters examined demonstrated an association with patient age, sex, or BMI in either symptomatic or asymptomatic hips. Labral tears and acetabular chondral lesions are common in the asymptomatic contralateral hip of patients undergoing surgery for FAI. The incidence of a symptomatic labral tear in these asymptomatic hips was 9% during 2 years of followup. We suggest that the decision to perform chondral or labral surgery in patients with FAI should be made with caution considering the relatively high prevalence of labral tears in asymptomatic hips and the low chance of development of symptoms. Level IV, case-series study.

Results of hip arthroscopy in patients with MRI diagnosis of subchondral cysts-a case series.

The aim of this article is to examine the results of arthroscopic management of patients with labral pathology who have preoperative magnetic resonance images (MRIs) demonstrating subchondral cysts. This institution’s database was searched for patients who underwent hip arthroscopy and had subchondral cysts on MRI and >2-year follow-up. Exclusion criteria included previous hip surgery, Tönnis grade >1, inflammatory arthritis, Perthes, slipped capital femoral epiphysis or abductor repair. Patient-reported outcome (PRO) scores including visual analog scale, modified Harris hip score (mHHS), non-arthritic hip score and hip outcome score sports-specific subscale (HOS-SSS) were gathered preoperatively, at 3 months, and annually thereafter. The change in PRO scores was compared with the minimally clinical important difference (MCID) to quantify improvement. Sixty-nine patients were eligible for this study, of which 65 (94%) had >2-year follow-up. All PROs were significantly improved at latest follow-up (P < 0.001). Mean patient satisfaction was 7.2. There was no correlation between Outerbridge grade III or IV cartilage damage noted during arthroscopy and subchondral femoral and acetabular cysts noted on MRI. Seventeen patients required reoperation [13 total hip arthroplasty (THAs) and 4 revision arthroscopies]. Patients with femoral subchondral cysts converted to THA 36% of the time. MCIDs for mHHS and HOS-SSS were surpassed by 63% and 68% of patients, respectively. Hip arthroscopies performed on patients with subchondral cysts present on preoperative MRI should be approached with caution. The rate of conversion to hip arthroplasty appears to be higher than that reported in the literature for patients who undergo arthroscopy without preoperative subchondral cysts. For patients who did not require hip arthroplasty or revision arthroscopy, patients demonstrated significant improvement in symptoms compared with the preoperative state.

Detection of Acetabular and Proximal Femoral Radiographic Abnormalities Showed by Hip Digital Tomosynthesis in Special Functional Position Compared with Conventional Radiography

Background: The acetabular and proximal femoral bone abnormalities are very common in the clinical practice. Conventional radiography has some difficulties in detecting early osseous changes. Digital tomosynthesis (DT) can remove the overlap of the anatomical structures, which improves the detection of early osseous changes. A special functional position can simulate the status of clinical symptoms; provide more evidence for clinical study of the acetabular and proximal femoral bone abnormalities and improve the accuracy. Objectives: To evaluate the diagnostic value of hip digital tomosynthesis at special functional position (DT-SFP) in detecting acetabular and proximal femoral radiographic abnormalities compared with conventional radiography. Patients and Methods: Ninety-four consecutive patients with discomfort around the hip joint underwent DT-SFP and conventional radiography. The imaging features of the acetabular and proximal femoral bone abnormalities were analyzed and the detection rate of the two methods was compared by chi-square test. Results: The herniation pits (HPs) of the femoral neck, acetabular/labral ossification, femoral head-neck junction bone protrusion, acetabular cysts, and acetabular osteophytes were detected by DT-SFP and conventional radiography. The detection rates of DT-SFP were 35%, 21%, 33%, 17% and 40% respectively, which were significantly higher than conventional radiography (21%, 9%, 10%, 7% and 31% respectively) (P = 0.000, 0.000, 0.000, 0.000, 0.001). The detection rate of coxa profunda, posterior wall sign and hip joint space narrowing showed no significant difference between using DT-SFP and conventional radiography (41%, 8% and 6% respectively) (P = 1.000, 1.000, 1.000). Conclusion: DT-SFP can improve the detection of relatively early bone abnormalities in acetabular and proximal femur compared with conventional radiography. DT-SFP can also observe the abnormal impact between acetabular and proximal femur.

Arthroscopic Bone Grafting of Deep Acetabular Cysts Using a Curved Delivery Device

Acetabular intraosseous cysts are frequently encountered in patients with dysplasia or femoroacetabular impingement. Small cysts are typically addressed by removing the cyst lining and stimulating healing via microfracture or abrasion chondroplasty. In contrast, larger cysts involving 1-3 cm3 frequently require additional fortification with bone graft material to facilitate osseous ingrowth and cyst healing. Previous arthroscopic reports have described the use of rim trimming to access the extra-articular side of the cyst, with subsequent use of straight metal cannulas for delivery of bone graft material. The downsides of this technique include the requirement for rim trimming, which may be ill advised in patients with normal coverage or dysplasia, as well as the creation of a second breach in the cyst wall, precluding pressurization of the bone graft material. We describe an arthroscopic technique using a curved delivery device allowing for deeper penetration into the cyst cavity through the articular side and greater delivery of bone graft material.

Is Subchondral Acetabular Edema or Cystic Change on MRI a Contraindication for Hip Arthroscopy in Patients With Femoroacetabular Impingement?

Background: The outcome for arthroscopic treatment of femoroacetabular impingement (FAI) can worsen with increasing arthritis. However, there remains a subset of hips with relatively maintained joint space but with acetabular subchondral edema and cystic change with unknown outcome on magnetic resonance imaging (MRI). Purpose: (1) To correlate MRI findings of subchondral acetabular edema/cystic change with arthroscopy grading of articular cartilage and (2) to determine whether postoperative outcome was worse for patients with subchondral edema/cystic change compared with a matched control group. Study Design: Cohort study; Level of evidence, 3. Methods: The records of all patients who underwent arthroscopic hip surgery for FAI at a single institution between 2007 and 2013 were reviewed for subchondral edema/cyst on preoperative MRI. Lesions were characterized by grade using an established classification system and were correlated with arthroscopic articular cartilage changes. A matched cohort of patients without evidence of subchondral edema or cyst was identified. Minimum 2-year outcomes were compared using prospectively collected Hip Outcome Score (HOS) activities of daily living and sport subscales as well as the modified Harris Hip Score (mHHS). Results: Overall, 104 patients were included. Thirty-six patients (18 men, 18 women) with a mean age of 41 years (range, 19-67 years) had subchondral edema, with or without the presence of cystic acetabular changes, at minimum 2-year follow-up (range, 24-60 months). Two patients who underwent total hip replacement were excluded in the outcome score comparison. Thirty-one of 34 patients (91%) had a grade 4 full-thickness cartilage lesion at the time of diagnostic arthroscopy. The mean mHHS was inferior for all patients with subchondral edema/cystic change (79.9 ± 18.7 vs 86.6 ± 12.5; P = .03), and the HOS was also lower (69.1 ± 27.0 vs 79.5 ± 21.4; P = .02). The overall success rate was 67% for all patients with subchondral edema/cystic change compared with 85% in the control group (P = .04). Conclusion: The presence of a subchondral edema with an acetabular cyst on MRI is indicative of a full-thickness cartilage lesion at the time of arthroscopy. These patients have inferior outcomes for arthroscopic treatment of FAI compared with patients with similar age and activity level without MRI subchondral cystic changes.

Is MRI Subchondral Acetabular Edema or Cystic Change a Contraindication for Hip Arthroscopy in Patients with FAI?

Objectives:Arthroscopic treatment for femoroacetabular impingement (FAI) generally has good results, but the outcome can worsen with increasing arthritis, largely defined as joint space narrowing. There remains a subset of hips with maintained joint space but with subchondral edema and cystic change of the acetabulum on MRI, with unknown outcome. Therefore, the purpose of this study was (1) to determine if postoperative outcome was worse for patients with subchondral edema on preoperative MRI compared to a matched control group and (2) to identify risk factors on MRI leading to inferior outcome.Methods:A review of patients who underwent arthroscopic hip surgery for FAI between 2007 and 2013 identified 530 patients. Of these, 39 patients had evidence of subchondral edema or subchondral cyst on the preoperative MRI with maintained joint space on preoperative radiographs. Lesions were characterized by grade, location and type using an established radiographic MRI classification system. A matched cohort of patients without evidence of subchondral edema or cyst was identified, and 2:1 matching was based on patient age, surgeon, surgery year within one year, surgical procedure, Tegner activity score, and Tonnis grade osteoarthritis changes on preoperative x-ray. Outcome was compared using the Hip Outcome Score and Modified Harris Hip Score between the two groups. Risk factors were then analyzed for type of lesion, grade and location of bone marrow lesion.Results:Thirty-nine patients (20 males, 19 females) showed preoperative MRI evidence of subchondral edema, and were followed for a mean of 23 months postoperatively (range, 12 - 60 months). Patients had an average age of 41 years (range, 19 - 67) and a preoperative Tegner score of 3.8 (range, 1 - 9). 87% of patients with subchondral cystic change had evidence of a grade IV full thickness cartilage lesion at the time of hip arthroscopy. Average Modified Harris Hip Scores were inferior for the subchondral group (79.9 ± 18.7) compared to the control group (86.6 ± 12.5; p = 0.027). In addition, Sport sub-scales of the Hip Outcome Score showed significantly lower scores for the subchondral group for both score (69.1 ± 27.0 vs. 79.5 ± 21.4, p = 0.018) and rating (66.7 ± 27.5 vs. 78.0 ± 20.8, p = 0.044). No radiographic risk factors, including type, location, or size of lesion were significant predictors of outcome. Two patients in the subchondral group were later converted to a total hip replacement.Conclusion:The presence of a subchondral acetabular cyst on MRI is indicative of a full thickness cartilage lesion at the time of arthroscopy. These patients have inferior outcomes for arthroscopic treatment of FAI compared to patients with similar age and activity level without MRI subchondral changes. Therefore, we recommend caution with consideration of hip arthroscopy in this patient subset.

Curved periacetabular osteotomy for the treatment of dysplastic hips.

Curved periacetabular osteotomy (CPO) was developed for the treatment of dysplastic hips in 1995. In CPO, the exposure of osteotomy sites and osteotomy of the ischium are made in the same manner as Bernese periacetabular osteotomy, and iliac and pubic osteotomies are performed in the same manner as rotational acetabular osteotomy. We studied the dynamic instabilities of 25 dysplastic hips before and after CPO using triaxial accelerometry. Overall magnitude of acceleration was significantly decreased from 2.30 ± 0.57 m/sec2 preoperatively to 1.55 ± 0.31 m/sec2 postoperatively. Pain relief and improvement of acetabular coverage resulting from acetabular reorientation seem to be related with reduction of dynamic instabilities of dysplastic hips. Isokinetic muscle strengths of 24 hips in 22 patients were measured preoperatively and after CPO. At 12 months postoperatively, the mean muscle strength exceeded the preoperative values. These results seem to be obtained due to no dissection of abductor muscles in CPO. The preoperative presence of acetabular cysts did not influence the results of CPO. An adequate rotation of the acetabular fragment induced cyst remodeling. Satisfactory results were obtained clinically and radiographically after CPO in patients aged 50 years or older. CPO alone for the treatment of severe dysplastic hips classified as subluxated hips of Severin group IV-b with preoperative CE angles of up to -20° could restore the acetabular coverage, weight-bearing area and medialization of the hip joint. CPO without any other combined procedure, as a treatment for 17 hips in 16 patients with Perthes-like deformities, produced good mid-term clinical and radiographic results. We have been performing CPO in conjunction with osteochondroplasty for the treatment of acatabular dysplasia associated with femoroacetabular impingement since 2006. The combined procedure has been providing effective correction of both acetabular dysplasia and associated femoral head-neck deformities without any increased complication rate. We have encountered an obturator artery injury in one case and two intraoperative comminuted fractures. Although serious complications such as motor nerve palsy, deep infection, necrosis of the femoral head or acetabulum, and delayed union or nonunion of the ilium were reported, such complications have never occurred in our 700 cases so far.

Rapid hip osteoarthritis development in a patient with anterior acetabular cyst with sagittal alignment change.

Rapidly destructive coxarthrosis (RDC) is rare and develops unusual clinical course. Recent studies suggest multiple possible mechanisms of the development of RDC. However the exact mechanism of RDC is still not clear. The difficulty of the study on RDC is attributed to its rareness and the fact that the data before the onset of RDC is normally unavailable. In this report, we presented the patient having the radiographic data before the onset who had rapid osteoarthritis (OA) development after contralateral THA, which meets the current criteria of RDC. We thought that the increased posterior tilt of the pelvis after THA reinforced the stress concentration at pre-existed anterior acetabular cyst, thereby the destruction of the cyst was occurred. As a result the rapid OA was developed. We think that there is the case of rapid osteoarthritis developing due to alternating load concentration by posterior pelvic tilt on preexisting anterior acetabular cyst such as our patient among the cases diagnosed as RDC without any identifiable etiology. The recognition of sagittal alignment changes and anterior acetabular cyst may play important role in prediction and prevention of the rapid hip osteoarthritis development similar to RDC.

Trilogy-constrained acetabular component for recurrent dislocation.

32 patients received a Trilogy- or Trilogy-Longevity-constrained acetabular liner for recurrent dislocations after total hip replacement. The constrained liner was inserted into a well-fixed Trilogy acetabular shell with snap fit. At 1.8-year followup (range 3–63 months), 4 patients had suffered further dislocation(s) (12%), and one patient had revision surgery for a loosened acetabular shell. Radiologic evaluation detected no definitively loose components, but one patient with progressing radiolucent lines around the femoral component and one patient with an acetabular cyst were found, as well as a patient with a loose locking ring (but otherwise no failure). The nineteen patients who were available for the present followup had a mean Harris Hip Score of 81. The constrained liner is an effective method of dealing with recurrent dislocations in well-fixed components.

Localised bone grafting of acetabular cysts during total hip replacement

Localised bone grafting of acetabular cysts during total hip replacement

Localised bone grafting of acetabular cysts during total hip replacement

Bone cysts are commonly found when preparing the acetabulum during a total hip replacement (Fig 1). We describe a simple yet effective technique of localised bone grafting using the Exeter™ (Stryker, Newbury, UK) plug trials already available when using the Exeter™ total hip system (Fig 2). Figure 1 Anteroposterior x-ray of right hip with a superiorly located acetabular cyst Figure 2 Exeter™ plug trial head is ideal for bone graft impaction within cyst The Exeter™ plug trials used to measure cement restrictors can be employed to pack bone graft into cysts. They are supplied in diameters from 6mm to 20mm and allow the surgeon to choose the appropriate sized plug trial to fit the bone cyst for optimal impaction. The long T-handle allows this technique to also be applied in overweight patients with deeply located acetabuli.

Subchondral cysts in dysplastic osteoarthritic hips communicate with the joint space: analysis using three-dimensional computed tomography

Bone cyst formation in hips increases as osteoarthritis worsens. Although bone cysts in hips have been described in many studies, their etiology remains unclear and under debate. The purpose of this study was to investigate the communication between a bone cyst and the joint space, as well as the relationship between the severity of osteoarthritis and the formation of subchondral bone cysts in dysplastic hips. We studied bone cysts from 150 dysplastic hips in 97 patients by computed tomography (CT) and plain radiography. We investigated the distribution of the bone cysts and the presence or absence of a communication path between the cysts and the joint space by three-dimensional (3D) CT. Of the 150 hips, 94 acetabula and 55 femoral heads were found to contain cysts. Of the 94 hips containing acetabular cysts, 89 and 5 hips showed black lines and gray lines connecting the cyst and the joint space, respectively, on 3D-CT. The rate of cyst presentation in the hip increased as the joint space became narrower. The number of hips that possessed cysts in the anterior and/or middle portion was significantly higher than that in the posterior portions. Bone cysts in dysplastic osteoarthritic hips were found to communicate with the joint space in all cases. This suggests that the formation and enlargement of the cysts in dysplastic hips may be greatly influenced by the joint fluid. Cyst formation was initially observed in the anterior acetabulum, gradually progressing to involve the entire joint, including the posterior acetabulum and the femoral head, with worsening of the osteoarthritis.

Cyst Volume in the Acetabulum and Femoral Head Decreases after Periacetabular Osteotomy

In a series of 26 consecutive patients scheduled for periacetabular osteotomy (PAO), we examined how many had acetabular or femoral head cysts, investigated whether the volume of the cysts changed after PAO, calculated the precision of the method applied and scored their hip symptoms. Magnetic resonance imaging (MRI) was performed before PAO and at 1 and 2½ years post-operatively. The number of cysts was noted and the total cyst volume in each patient was estimated with a design-based stereological method and the precision of the method was calculated.The patients filled out The Hip disability and Osteoarthritis Outcome Score (HOOS) four years after PAO. Preoperatively, 12 patients had acetabular or femoral head cysts (22 cysts), 1 year postoperative, 15 patients had cysts (23 cysts) and 2½ years postoperative, 15 patients had cysts (18 cysts). Mean total acetabular cyst volume per patient decreased significantly from 1 year (1.96 cm³, SD 3.97) to 2½ years (0.96 cm³, SD 1.70) after PAO (p= 0.04). The Limits Of Agreement for measurement of cyst volume was ± 1.73 cm³. The mean subscore for Pain was 75, Symptoms 75, ADL 83, Sport/recreation 63 and Quality Of Life 62. The number of patients having cysts did not change notably after PAO. But the mean total cyst volume/patient decreased significantly between 1 and 2½ years after PAO. The PAO patients rated their hip comparable to the scores for patients six months after total hip replacement.

Arthroscopic Grafting of Chondral Defects and Subchondral Cysts of the Acetabulum

We present a novel arthroscopic-assisted technique to graft chondral defects and subchondral cysts of the acetabular socket using a synthetic osteochondral plug. Four patients with groin pain, solitary cysts in the roof of the acetabulum and radiographic evidence of early osteoarthritis were treated. A bone tunnel was prepared from the region of the iliac crest to the acetabular articular surface. A synthetic osteochondral plug was inserted in an ante-grade fashion and positioned flush with the lunate articular cartilage. The minimum follow-up from surgery was 8 months (mean 10 months, range 8 to 11 months). There were no peri-operative complications related to the procedure. All patients reported an improvement in symptoms and function at the latest follow-up. One of the patients underwent a re-look arthroscopy at 5 months for persistent dull groin and buttock pain. Capsular adhesions of the labrum were identified and released. The mean non-arthritic hip score improved from 53.8 (range 43.8 to 70) pre-operatively to 84.6 (range 78.8 to 87.5) at 6 months. Computed tomography and magnetic resonance imaging at 6 months confirmed the stability of the osteochondral plugs and on-going healing. This procedure offers an arthroscopic means to treat patients with solitary acetabular cysts and may prove effective for chondral grafting of denuded acetabular areas in early to moderate degenerative hip disease.