Osteonecrosis of the knee: a review of three disorders

Does the osteonecrotic volume/other factors predict progression to total knee arthroplasty in spontaneous osteonecrosis of the knee? An MRI study

Background

The aim of this study is to determine whether the volume of the osteonecrotic lesion in spontaneous osteonecrosis of the knee (SONK) or other prognostic factors predict progression to total knee arthroplasty (TKA). The secondary aim is to analyse co-relation of volume of osteonecrotic lesion versus other prognostic factors The authors hypothesize that a greater osteonecrotic volume predicts progression to TKA.

Materials and methods

A retrospective study was conducted at a single tertiary hospital. All patients under the care of a single surgeon with magnetic resonance imaging (MRI)-proven SONK were included from the period of January 2011 to January 2018. Survival analysis was conducted to evaluate for progression to TKA based on volume and location of osteonecrotic lesion. Univariate and multivariate analyses were performed to identify potential risk factors for TKA.

Results

42 patients with MRI-proven SONK were evaluated. 9 patients (21.4 %) required TKA. There was no significant association between progression to TKA with volume of the osteonecrotic lesion. Other factors such as age, gender, body mass index, degree of bony edema and cartilage damage, presence of meniscal tear and subchondral fractures and location of osteonecrotic lesion were also not significant.

Conclusion

The volume of the osteonecrotic lesion and other evaluated prognostic factors were not predictive of the progression to TKA for patients with SONK.

Spontaneous Osteonecrosis of Knee: A Case Report

A 49-year-old man with no prior history of trauma, steroid use, or alcohol consumption presented with spontaneously developing progressive left knee discomfort that worsened after intense activity for 1.5 years. Normal x-rays indicated local discomfort along the joint line, and magnetic resonance imaging (MRI) revealed a T1-weighted hypointense line with bone infarcts in the medial and lateral condyle and the lower part of the left femur in addition to diffuse bone edema. Spontaneous osteonecrosis of the knee (SONK) was identified. Initially, he was treated conservatively with painkillers and calcium supplements. Then, the patient showed a significant improvement.

Spontaneous Osteonecrosis of the Knee: State of the Art

Osteonecrosis is a terrible condition that can cause advanced arthritis in a number of joints, including the knee. The three types of osteonecrosis that can affect the knee are secondary, post-arthroscopic, and spontaneous osteonecrosis of the knee (SPONK). Regardless of osteonecrosis classification, treatment for this condition seeks to prevent further development or postpone the onset of knee end-stage arthritis. Joint arthroplasty is the best course of action whenever there is significant joint surface collapse or there are signs of degenerative arthritis. The non-operative options for treatment at the moment include observation, nonsteroidal anti-inflammatory medications (NSAIDs), protective weight bearing, and analgesia if needed. Depending on the severity and type of the condition, operational procedures may include unilateral knee arthroplasty (UKA), total knee arthroplasty (TKA), or joint preservation surgery. Joint preservation techniques, such as arthroscopy, core decompression, osteochondral autograft, and bone grafting, are frequently used in precollapse and some postcollapse lesions, when the articular cartilage is typically unaffected and only the underlying subchondral bone is affected. In contrast, operations that try to save the joint following significant subchondral collapse are rarely successful and joint replacement is required to ease discomfort. This article's goal is to summarise the most recent research on evaluations, clinical examinations, imaging and various therapeutic strategies for osteonecrosis of the knee, including lesion surveillance, medicines, joint preservation methods, and total joint arthroplasty.

MRI Bone Abnormality of the Knee following Ultrasound Therapy: Case Report and Short Review

Ultrasound (US) therapy in sports and medical pathologies is widely used by many physiotherapists and sports medicine clinicians; however, data regarding their potential side effects remain rare. We report a case of a 21-year-old woman with iliotibial band (ITB) syndrome treated with a physiotherapy session combined with US therapy. She had twenty 7 min US sessions on the knee, for 3 months (US at 1 Mhz with an intensity between 1 and 2 W/cm²). Due to persistence of the ITB syndrome's symptomatology after the 3 months of physiotherapy sessions, an MRI (magnetic resonance imaging) was carried out and revealed osteonecrosis-like bone abnormalities on the external femoral condyle, the external tibial plateau, and the proximal fibula. In view of these lesions, the ultrasonic therapy was stopped, and a repeat MRI demonstrated the progressive disappearance of these imaging abnormalities one year after the last US (ultrasound) treatment. In light of this case, we propose here a short review of reported osseous "osteonecrosis" abnormalities associated with US therapies.

[Drug treatment of osteonecrosis]

The medicinal treatment of osteonecrosis is described as part of the conservative treatment for atraumatic femoral head necrosis of the hip in adults and for Ahlbäck's disease of the knee joint. For femoral head necrosis, iloprost is used in the early stages (ARCO I and II) as a treatment attempt to eliminate pain and the accompanying bone marrow edema. This also applies to the use of bisphosphonates, whereby preferably small defects (< 30%) are suitable for treatment. Bisphosphonates are successfully used in the knee joint to treat Ahlbäck's disease, although the results are sometimes contradictory. Other locations, such as the humeral head, talus, scaphoid, lunate, proximal tibia, and metatarsal head, are sometimes successfully treated with bisphosphonates. Although the results seem promising, the groups are far too small to derive treatment recommendations in this regard.

Satisfactory Outcomes of All-Poly Fixed Bearing Unicompartmental Knee Arthroplasty for Avascular Osteonecrosis Versus Osteoarthritis: A Comparative Study With 10 to 22 Years of Follow-up

BACKGROUND

While good mid-term results for treating spontaneous knee osteonecrosis (SPONK) with unicompartmental knee arthroplasty (UKA) have been reported, concerns remain about implant survival at long-term. This study aimed to compare outcomes and survivorship of UKA for SPONK vs osteoarthritis at a minimum of 10 years.

METHODS

This case-control study included medial UKA for femoral SPONK operated between 1996 and 2010 with a minimum 10-year follow-up (n = 47). Each case was matched with a medial UKA for osteoarthritis based on body mass index (BMI), gender, and age. Knee Society Score (KSS), complications and radiological (loosening) data were collected at the last follow-up. Kaplan-Meier survivorship analysis was performed using revision implant removal as endpoint.

RESULTS

The mean follow-up was 13.2 years (range 10 to 21 years). Mean age and BMI were 72.9 ± 8.4 years and 25.5 ± 3.6 Kg/m² in SPONK group. At last follow-up, knee and function KSS were 89.5 ± 12 and 79 ± 18 in SPONK group vs 90 ± 15 (P = .85) and 81.7 ± 17 (P = .47) in control group. Complications and radiological results showed no significant differences. The survival rate free from any revision was 85.1% at last follow-up in SPONK group and 93.6% in control group (P = .23). The leading cause for revision was aseptic tibial loosening (57.1%) in SPONK group. The 15-year survival estimate was 83% in SPONK group.

CONCLUSION

Satisfactory clinical outcomes at long-term after UKA for femoral SPONK were observed, similar to those after UKA for osteoarthritis, despite a higher risk of tibial loosening in the SPONK group. No symptomatic femoral loosening leading to a revision was observed.

LEVEL OF EVIDENCE

IV.

A Case of Subchondral Insufficiency Fracture of the Knee at Lateral Femoral Condyle Treated With Unicompartmental Knee Arthroplasty

Spontaneous insufficiency fracture of the knee is a potentially devastating yet poorly understood disease entity that can lead to secondary osteoarthritis. Most cases involve the medial femoral condyle, and the lateral femoral condyle is rarely affected. The optimal treatment for spontaneous insufficiency fracture of the lateral femoral condyle remains undetermined, and there are no previous dedicated reports on treatment outcome with unicompartmental knee arthroplasty. A middle-aged lady presented with subacute left knee pain and a locked knee. Subsequent imaging studies revealed a spontaneous insufficiency fracture of the lateral femoral condyle. In view of the isolated compartment involvement, unicompartmental knee arthroplasty was performed with satisfactory outcome. At 1 year postoperatively, the patient had complete resolution of knee pain and was able to resume working.

Regeneration of Bone Defects in a Rabbit Femoral Osteonecrosis Model Using 3D-Printed Poly (Epsilon-Caprolactone)/Nanoparticulate Willemite Composite Scaffolds

Steroid-associated osteonecrosis (SAON) is a chronic disease that leads to the destruction and collapse of bone near the joint that is subjected to weight bearing, ultimately resulting in a loss of hip and knee function. Zn2+ ions, as an essential trace element, have functional roles in improving the immunophysiological cellular environment, accelerating bone regeneration, and inhibiting biofilm formation. In this study, we reconstruct SAON lesions with a three-dimensional (3D)-a printed composite made of poly (epsilon-caprolactone) (PCL) and nanoparticulate Willemite (npW). Rabbit bone marrow stem cells were used to evaluate the cytocompatibility and osteogenic differentiation capability of the PCL/npW composite scaffolds. The 2-month bone regeneration was assessed by a Micro-computed tomography (micro-CT) scan and the expression of bone regeneration proteins by Western blot. Compared with the neat PCL group, PCL/npW scaffolds exhibited significantly increased cytocompatibility and osteogenic activity. This finding reveals a new concept for the design of a 3D-printed PCL/npW composite-based bone substitute for the early treatment of osteonecrosis defects.

Medial meniscus extrusion as a predictor for a poor prognosis in patients with spontaneous osteonecrosis of the knee

BACKGROUND

Risk factors for the progression of spontaneous osteonecrosis of the knee (SONK) remain unclear. The purpose of this study was to investigate the association between magnetic resonance imaging (MRI) findings of the meniscus and the prognosis of SONK.

METHODS

A total of 78 consecutive patients (female 85%; mean age 75.6 ± 7.2 years old) diagnosed with SONK were included. Of these, 30 patients did not receive surgery within 1 year from the onset of SONK (conservative group), while the remaining 48 patients underwent unicompartmental knee arthroplasty due to worsening of symptoms (UKA group). Using MRI findings obtained within 3 months of the onset, we compared the types of meniscus tear and medial meniscus extrusion between the conservative group and UKA group. We performed a receiver operating characteristics (ROC) analysis to estimate the cut-off value.

RESULTS

Patients in the UKA group showed greater medial meniscus extrusion (absolute value, 4.2 mm ± 1.9 vs. 2.8 mm ± 1.2, P = 0.001; relative percentage of extrusion (RPE), 45.7% ± 21.5 vs. 30.7% ± 12.9, P = 0.001) and a higher prevalence of radial tear (P = 0.021) than those in the conservative group. In the multivariate analysis, RPE remained a relevant independent factor (P = 0.035) for future UKA. An ROC analysis found that the cut-off point of RPE was 33% (sensitivity, 81.2%; specificity, 63.3%).

CONCLUSION

RPE was a predictor of the prognosis of patients who underwent UKA within 1 year after the onset of SONK. Our results suggest that patients with RPE ≥ 33% are at high risk for progression.

Post-arthroscopic Subchondral Insufficiency Fractures of the Knee Yield High Rate of Conversion to Arthroplasty

PURPOSE

To evaluate both the potential causes and resultant outcomes in patients in whom subchondral insufficiency fracture of the knee (SIFK) develops after arthroscopy.

METHODS

We performed a retrospective review of all patients with a magnetic resonance imaging diagnosis of SIFK after arthroscopic meniscectomy and chondroplasty over a 12-year period.

RESULTS

A total of 28 patients were included, with a mean age of 61 years and mean follow-up period of 5.7 years. SIFK showed a predilection for the medial compartment (n = 25, 89%), specifically the medial femoral condyle (n = 21, 75%). In 7 patients (25%), SIFK developed in both the femoral condyle and tibial plateau in the ipsilateral compartment. Fifteen patients (54%) went on to conversion to arthroplasty at a mean of 0.72 years. The rate of survival free of conversion to arthroplasty was 57%, 45%, and 40% at 1 year, 2 years, and 5 years, respectively. Furthermore, 63% of patients with a meniscal tear and SIFK in the same compartment went on to arthroplasty (P = .04). There was an increased risk of conversion to arthroplasty if SIFK was present in both the femur and tibia in the same compartment (P = .04). A higher Kellgren-Lawrence grade at the time of the SIFK diagnosis increased the likelihood of eventual arthroplasty (P = .03). The presence of SIFK in both the femur and tibia in the ipsilateral compartment, an increased Kellgren-Lawrence grade, and a meniscal tear or prior meniscectomy in the same compartment as SIFK were associated with an increased risk of eventual arthroplasty.

CONCLUSIONS

Post-arthroscopic SIFK most commonly occurs in the medial compartment, particularly in patients who underwent a prior meniscectomy. The presence of meniscal root and radial tears in these patients is notable (75%). Ultimately, there is a high rate of progression of arthrosis (33%) and eventual conversion to arthroplasty.

LEVEL OF EVIDENCE

Level IV, case series.

The Fate of Bone Marrow Lesions After Open Wedge High Tibial Osteotomy: A Comparison Between Knees With Primary Osteoarthritis and Subchondral Insufficiency Fractures

BACKGROUND

Subchondral insufficiency fracture of the knee (SIFK) is characterized by a subchondral lesion that may lead to end-stage osteoarthritis (OA). In patients who have SIFK in a precollapse state with varus malalignment, a joint-preserving technique such as open wedge high tibial osteotomy (OWHTO) should be considered.

PURPOSE

To evaluate the efficacy of OWHTO in primary OA and SIFK-dominant OA by clinical and radiological evaluations including magnetic resonance imaging (MRI).

STUDY DESIGN

Cohort study; Level of evidence 3.

METHODS

A total of 33 SIFK-dominant OA knees and 66 with primary OA that underwent biplanar OWHTO between March 2014 and February 2016 were included after 1:2 propensity score matching. The MRI Osteoarthritis Knee Score was used to assess bone marrow lesions (BMLs) preoperatively and at follow-up. The weightbearing line ratio, the hip-knee-ankle angle, and the joint line convergence angle were measured. The clinical outcomes assessed were range of motion, the American Knee Society Score, and the Western Ontario and McMaster University (WOMAC) score.

RESULTS

The mean follow-up period was 41.2 ± 12.6 months. The distribution of preoperative BML grade in the SIFK-dominant OA group was significantly higher in both the femur and tibia (P < .001 and <.001, respectively) than that in the primary OA group. However, the difference was not significant postoperatively (femur, P = .425; tibia, P = .462). In both groups, postoperative BMLs showed significant improvement compared with preoperative BMLs (primary OA [femur, P < .001; tibia, P = .001] and SIFK-dominant OA [femur, P < .001; tibia, P < .001]). The WOMAC pain score was higher in the SIFK-dominant OA group preoperatively (primary OA, 7.0 ± 3.73; SIFK-dominant OA, 9.17 ± 2.6; P = .032) even though it was not different at the final follow-up (primary OA, 2.11 ± 1.7; SIFK-dominant OA, 1.79 ± 1.32; P = .179).

CONCLUSION

OWHTO is an effective procedure not only for primary OA but also for SIFK-dominant OA. OWHTO can improve BMLs, which represent the main pathological feature of SIFK. Therefore, in patients who have SIFK with varus malalignment, OWHTO can be an attractive treatment option for preserving the joint and enhancing subchondral bone healing.

Multiple Joint Osteonecrosis in a Patient on Long-term Intranasal Corticosteroids

We present the first report of bilateral knee and left ankle osteonecrosis in a 58-year-old female patient on long-term intranasal corticosteroids. Initially, our patient presented with progressive disabling knee pain with normal radiographs. The patient was presumed to have mild degenerative joint disease; therefore, she was treated conservatively. Then, the patient developed severe left ankle pain, and she was thought to have L5/S1 radiculopathy; therefore, she underwent epidural steroid injection that did not provide any benefit. However, extensive bilateral osteonecrosis of the medial tibial plateau in addition to osteonecrosis of the talus bone of left ankle were later diagnosed by MRI. The patient underwent staged bilateral total knee arthroplasty. In conclusion, the diagnosis of osteonecrosis might be challenging because of overlapping clinical presentation with other disorders particularly in the early stage of the disease with normal radiographs. Therefore, a high index of suspicion and thorough history with supplemental MRI imaging are essential for the assessment of patients presented with atypical refractory joint pain particularly in the presence of risk factors.

Alternate treatment approach to subchondral insufficiency fracture of the knee utilizing genicular nerve cooled radiofrequency ablation and adjunctive bisphosphonate supplementation: A case report

Subchondral insufficiency fractures of the knee are commonly misdiagnosed fractures that are both very painful and difficult to treat. A conservative treatment modality to control symptoms during rehabilitation has not previously been described. This case report presents the alternate use of cooled radiofrequency ablation technique of the genicular nerves for pain relief and bisphosphonate infusion to address the underlying poor bone mineralization/density with imaging follow-up before and after instituted treatments. A middle-aged female patient presenting with atraumatic pain in the medial aspect of the left knee diagnosed on an original magnetic resonance imaging as an insufficiency fracture and debilitating pain. Multiple-surgeon opinions of total knee arthroplasty were not a consideration the patient wanted or could consider given her lifestyle. Cooled radiofrequency ablation of the genicular nerve branches was performed with significant-complete pain relief achieved that lasted at least 6 months. Bisphosphonate infusions were instituted to address the underlying osteoporosis detected by a dual energy X-ray absorptiometry (DEXA) scan. Clinical performance after the radiofrequency ablations was followed with clinically validated surveys (The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)/Knee Injury and Osteoarthritis Outcome Score (KOOS)) at 2 weeks, 1, 3, and 6 months. Patient was also asked to follow a restricted-modified weight-bearing plan for 3 months followed by physical therapy. Eight weeks apart of bisphosphonate infusions were delivered after proper administration of vitamin D. There was resolution of the insufficiency fracture at the medial femoral condyle between the magnetic resonance imaging exams within 4.5 months apart treated with restricted weight-bearing regimen. Pain resolution, significant improved function, and range of motion were the end results of our instituted treatment plan. This case reports presents an alternate pathway for the treatment of this condition especially when there is lack of consensus among physicians in how to best address this condition.

Spontaneous osteonecrosis of the knee: what do we know so far? A literature review

PURPOSE

Spontaneous osteonecrosis of the knee (SONK) is said to be a relatively common disease which may lead to an end-stage osteoarthritis of the knee. The aim of this paper was to review the literature on this field published until now, discuss the results of both conservative and surgical treatment options, as well as to introduce new methods of treatment, which may be applicable in SONK treatment.

METHODS

We searched the PubMed and Cochrane databases until November 2019 and presented the most recent findings in this work.

RESULTS

The exact aetiology of SONK still remains unclear; however, recent studies suggested that early stage of SONK is rather a result of the subchondral fracture than primary osteonecrosis. So far described conservative treatment includes non-weight bearing or protected weight bearing with a knee brace, nonsteroidal anti-inflammatory drugs, analgesics, and bisphosphonates. Surgical management includes arthroscopic debridement, core decompression, osteochondral autograft, high tibial osteotomy, and unicompartmental knee arthroplasty or total knee arthroplasty.

CONCLUSIONS

Although the aetiology of SONK remains unknown, there are many treatment options, and the choice of the most suitable one is challenging. We think that subchondroplasty may be one of the effective methods.

Medial meniscal extrusion and spontaneous osteonecrosis of the knee

PURPOSE

Causes of spontaneous osteonecrosis of the knee (SONK) have not been clearly elucidated. This study investigated the relationship between medial meniscal extrusion and SONK.

METHODS

We reviewed 108 SONK knees and determined their Aglietti stage. Meniscal extrusion is defined when it extends beyond the medial margin of tibial plateau and osteophytes are excluded for determining the margin. Both absolute extrusion (AE) and relative percentage of extrusion (RPE) were measured, and meniscal tear patterns were evaluated in the early stages of SONK (I and II).

RESULTS

All knees had meniscal extrusion. Stage I was detected in 39 knees; II, in 23; III, in 16; IV, in 18; and V, in 12. The mean AE and RPE were 4.2 mm and 42% in stage I, 5.0 mm and 52% in stage II, 6.8 mm and 71% in stage III, 7.0 mm and 69% in stage IV, and 7.8 mm and 80% in stage V, respectively. The knees in the early stages showed less AE and RPE than those in late stages IV (p < 0.05) and V (p < 0.01). Additionally, the level of AE (ρ = 0.63, p < 0.0001) and RPE (ρ = 0.58, p < 0.0001) correlated with the SONK stage. Of knees with early-stage SONK, 12 knees had no tear, 26 had horizontal tears, 1 had longitudinal tear, 6 had degenerative tears, 2 had radial tears, 1 had complex tear, and 14 had root tears. Neither AE nor RPE differed significantly among tear patterns.

CONCLUSIONS

Meniscal extrusion was recognized even in early stages, with a significant correlation between the SONK stage and extrusion. Although the most frequent tear pattern in early-stage SONK was horizontal tear, 12 knees had meniscal extrusion with no tears. Therefore, meniscal extrusion, which indicates meniscal dysfunction, may be a cause of SONK and be related with the developmental stage of SONK.

Clinical Characteristics and Treatment of Spontaneous Osteonecrosis of Medial Tibial Plateau: A Retrospective Case Study

Background:

In a small proportion of cases, spontaneous osteonecrosis of the knee (SONK) involves the medial tibial plateau (MT). Here, we introduced the clinical characteristics of spontaneous osteonecrosis of the MT and unicompartmental knee arthroplasty (UKA) as the favorable treatment for this situation based on a retrospective case study.

Methods:

Patients with spontaneous osteonecrosis of the MT, confirmed by magnetic resonance imaging (MRI) at Guangdong Provincial Hospital of Chinese Medicine (China) from March 2015 to June 2016, were included as a case serial and analyzed retrospectively. All patients underwent Oxford Medial UKA. The characteristics of their lesions, corresponding treatment, and results of follow-up were presented. The lesion scores and grade were determined according to the criteria of Ficat and Arlet.

Results:

In total, 22 patients (5 men, 17 women; mean age, 64.1 years) with spontaneous osteonecrosis of the MT were analyzed. The lesion stages assessment showed that 3 (14%) were Stage II, 10 (45%) were Stage III, 7 (32%) were Stage IV, and 2 (9%) were Stage V. In the sagittal plane, 7 (32%) were in the anterior region (MTa) and 15 (68%) were central (MTc). The lesion volume averaged 2.24 ± 0.79 cm³ (range: 1.57–3.08 cm³). Seventeen patients (77%) had Level III posterior medial meniscus root tears (MMRTs). All the patients underwent UKA. Average follow-up was 30.0 ± 6.4 months with a range of 23.0–38.0 months. The visual analog scale score was 7.78 ± 0.67 before surgery while decreased to 2.22 ± 1.09 at the final follow-up (P < 0.001). The Hospital for Special Surgery scores of pre-/post-surgery were 65.67 ± 5.45 and 84.10 ± 4.20, respectively (P < 0.001).

Conclusions:

SONK often occurs in the anterior and central tibial plateau due to abnormal stresses. Most of the patients had Level III posterior medial meniscus root tears. MRI is recommended for suspected cases to identify SONK at an early stage. The use of the Oxford Medial UKA for SONK of the MT is reliable both immediately and at follow-up.

The Role of Meniscal Tears in Spontaneous Osteonecrosis of the Knee: A Systematic Review of Suspected Etiology and a Call to Revisit Nomenclature

BACKGROUND

The cause of spontaneous osteonecrosis of the knee (SONK) and postarthroscopic osteonecrosis of the knee is unknown, and the mechanisms involved have been poorly characterized.

HYPOTHESIS/PURPOSE

The purpose of this study was to perform a detailed systematic review of the literature to examine proposed etiological mechanisms for SONK in order to establish an improved understanding of the processes involved. We hypothesized that the etiology of SONK would be multifactorial.

STUDY DESIGN

Systematic review.

METHODS

A systematic review of the literature was performed by searching PubMed, Medline, Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials. Inclusion criteria were all original research articles presented in the English language that reported on the suspected etiology of SONK. Reviews, case reports with fewer than 3 patients, cost-effectiveness studies, technical reports, editorial articles, surveys, special topics, letters to the editor, personal correspondence, and studies that only proposed factors for the progression of SONK were excluded.

RESULTS

After a comprehensive review of 255 articles, 26 articles were included for final analysis. Twenty-one (80.7%) of 26 articles implicated the role of the meniscus in the development of SONK, in an association with either meniscal tears or its development after meniscectomy. The medial meniscus and posterior meniscal root tears were implicated more frequently. All 4 studies incorporating histological findings supported the insufficiency fracture hypothesis as a pathological basis of SONK.

CONCLUSION

Physicians should be cognizant of the high prevalence of medial meniscus root tears in patients with SONK. Meniscectomy and meniscal tears, particularly of the medial meniscus posterior root, increase contact pressures and create an environment from which insufficiency fractures can emanate. We believe the term SONK is a misrepresentation of the etiology and pathogenesis of the condition and should be replaced with subchondral insufficiency fractures of the knee. Further elucidation of the etiology is required.

Osteochondral allograft in a patient with avascular necrosis of the knee secondary to lupus

Joint preservation surgery is accepted in cases of secondary osteonecrosis of the knee without joint collapse. However, there is no consensus on the best treatment: debridement and drilling, or use of auto- or allograft. The author describes a clinical case with 15 years of evolution where allogeneic osteochondral graft was used in the treatment of osteonecrosis of the lateral femoral condyle in a young woman with systemic lupus. In spite of having other options and of the results reported in the literature, the functional evaluation 15 years later presented excellent results, with total autonomy of the patient for daily life and work tasks, indicating that the option for osteochondral allograft may be a good solution.

Reliable patient-reported outcome measure and survivorship of UKA for primary spontaneous osteonecrosis

PURPOSE

Primary Spontaneous osteonecrosis of the knee (SPONK) was a result of a subchondral insufficiency fracture based on histopathological examinations. There were few studies examining patients who underwent unicompartmental knee arthroplasty (UKA) for the treatment of primary SPONK. The aim of this study was to investigate (1) patient-reported outcome measure (PROM), (2) survivorship of revision as end point and (3) survivorship of complication as end point in patients with primary SPONK.

METHODS

The clinical examinations of a consecutive series of 61 medial UKAs for primary SPONK of the medial femoral condyle from 2008 to 2012 were evaluated retrospectively at our institution. There were 18 males and 43 females with a mean age of 73.7 years (60-91). In all patients, preoperative radiographs were analyzed according to the stage of primary SPONK. We conducted Kaplan-Meier survival analyses using revision and complications for any reasons as the end point.

RESULTS

Mean follow-up was 6.6 years (range 6-10). UKA using Physica ZUK (LIMA Corporate. UD, Italy) for SPONK improved patients' 2011 Knee Society symptom score, patient satisfaction, patient activities, EQ-5D and postoperative ranges of motion compared with their preoperative status (P < 0.01). Revision surgery was required in one knee (1.6%) due to postoperative fracture of the medial tibial plateau after a fall that occurred 6 months postoperatively. The projected rate of survivorship of UKA was 90.4% at 10 years (95% confidence interval 0.80-1). The projected rate of survivorship with complication at end point was 87.7% at 10 years (95% confidence interval 0.76-0.99).

CONCLUSION

The present study demonstrated that primary spontaneous osteonecrosis of the knee (SPONK) can be successfully be treated with UKA at a mean follow-up of 6.6 years.

LEVEL OF EVIDENCE

II.

Metaphyseal burst sign: A secondary sign on MRI of subchondral insufficiency fracture of the knee

INTRODUCTION

To describe a novel secondary sign of subchondral insufficiency fracture of the knee, metaphyseal burst sign (soft tissue oedema in the meta-epiphyseal region of the affected condyle).

METHODS

An electronic database research of 7926 knee MRI examinations was performed. Forty-eight scans were included in the study. The diagnosis of subchondral insufficiency fracture (SIF) was confirmed in a consensus review by one fellowship trained musculoskeletal (MSK) radiologist and one radiology fellow. The presence of metaphyseal burst sign was evaluated in the cohort.

RESULTS

Forty-one patients were included in the study (21 males, 20 females). The mean age was 61.5 years (range 41-80 years). The anatomical location was medial femoral condyle (n = 28), the lateral femoral condyle (n = 5) and medial tibial condyle (n = 8). The metaphyseal burst sign was present in 45 of the 48 scans reviewed. The average craniocaudal length of the soft tissue oedema defined as metaphyseal burst sign was 7 cm (range 10.5 to 4.5).

CONCLUSION

The metaphyseal burst sign is an early, indirect sign of SIF.

Characteristics, management, and outcomes of spontaneous osteonecrosis of the knee in Indian population

PURPOSE

Spontaneous osteonecrosis of the knee affects the medial femoral condyle in patients above 55 years of age. Many reports and studies are available from western countries. But there is a gross paucity of literature on spontaneous osteonecrosis of the knee (SPONK) in the Indian subcontinent, either it is under-reported or detected at a later stage. The aim of our study was to detect SPONK in Indian population and describe its characteristics, treatment, and outcome.

MATERIAL AND METHOD

A prospective study was conducted over a period of three years. All patients above 18 years with knee pain at rest and medial condyle tenderness without joint laxity were evaluated with plain radiographs and MRI. Further tests were done if radiological signs of osteonecrosis were present. Various parameters were recoded like Visual Analog Scale (VAS), Knee Society Score (KSS), and MRI Osteoarthritis Knee Score. Conservative treatment consisted of a combination of NSAIDs and bisphosphonates. Decompression with bone grafting was done if there was no improvement or deterioration at three month follow-up.

RESULTS

Ten patients were diagnosed with SPONK. The mean age was 50 years with male predominance (60%) with the involvement of medial femoral condyle (80%) or left knee (70%). Most cases were in Koshino stage 1. Mean VAS was 6.5 and mean KSS was 59. All clinical parameters showed improvement at one year.

DISCUSSION

A study with a bigger sample size and longer follow-up is needed to fill the lacunae of literature on this topic from the Indian subcontinent. In spite of the limitations, we did observe that in our population, males were more commonly affected than females, which is contrary to most studies on the subject. Also, the disease had an early age of onset (50 years) in Indian population as compared to Western and East Asian populations.

CONCLUSION

Combined therapy of NSAIDs and bisphosphonates shows excellent results over a period of one year. Joint-preserving surgeries are effective even in Koshino stage 3 SPONK.

Mosaic Osteochondral Autograft Transplantation Versus Bone Marrow Stimulation Technique as a Concomitant Procedure With Opening-Wedge High Tibial Osteotomy for Spontaneous Osteonecrosis of the Medial Femoral Condyle

PURPOSE

To evaluate the effects of osteochondral autograft transplantation (OAT) mosaicplasty as a concomitant procedure with opening-wedge valgus high tibial osteotomy (HTO) for spontaneous osteonecrosis of the medial femoral condyle (MFC) on clinical outcomes and cartilage status in comparison with bone marrow stimulation (BMS) by drilling, and to assess the relation between lesion size and postoperative cartilage status.

METHODS

Fifty-eight patients with spontaneous osteonecrosis of the MFC were treated with opening-wedge HTO and a concomitant procedure of BMS (28 patients) or OAT (30 patients). Clinical evaluation was carried out using the Knee Society Score at postoperative 2 years. Postoperative status of articular cartilage was assessed by arthroscopy according to the International Cartilage Repair Society (ICRS) grade at the time of plate removal.

RESULTS

The Knee Society Score objective score and function score were improved at postoperative 2 years compared with preoperative value in both groups, but no significant difference was found between the 2 groups. According to the ICRS overall repair grade, cartilage status was rated as normal or nearly normal (ICRS overall score ≥8) in 41% of the BMS group and 90% of the OAT group. The results suggested that cartilage repair in OAT was significantly better than that in BMS (P = .0015). Furthermore, the BMS group revealed that repair with normal or nearly normal was observed in all less than 4 cm² of lesion size, whereas the OAT group exhibited that repair with normal or nearly normal was independent of lesion size.

CONCLUSIONS

This study suggested that OAT is superior to BMS as a concomitant procedure with opening-wedge valgus HTO for spontaneous osteonecrosis of the MFC in the success of cartilage repair. However, clinical outcomes were not significantly different between these 2 procedures. When treating the lesion larger than 4 cm² by joint-preserving surgery, OAT mosaicplasty is recommended as a concomitant procedure with HTO.

LEVEL OF EVIDENCE

Level III, therapeutic case-control study.

Diseases of Subchondral Bone 2

Osteonecrosis of the knee can be divided into the following 3 categories: primary or Spontaneous osteonecrosis of the knee (SONK), secondary osteonecrosis (ON), and postarthroscopic osteonecrosis. Patient characteristics as well as underlying risk factors can help categorize the type of osteonecrosis and guide treatment. SONK was &filig;rst described by Ahlback et al in 1968. It is described as a disease of subchondral bone that leads to focal ischemia and bone marrow edema, necrosis, and possible subsequent structural collapse. SONK typically presents in the older women with frequent involvement of the medial femoral condyle. Secondary osteonecrosis is typically present in patients below 55 years of age. Unlike SONK, secondary ON presents multiple foci of bone marrow involvement with extension into the metaphysis and diaphysis. Postarthroscopic ON has been described after arthroscopic meniscectomy, shaver-assisted chondroplasty, anterior cruciate ligament reconstruction, and laser or radiofrequency-assisted debridement.

Predictive factors for the progression of spontaneous osteonecrosis of the knee

PURPOSE

To assess potentially predictive factors that were evaluated 1 year after the onset of symptoms in patients with spontaneous osteonecrosis of the knee (SONK) and to determine receiver operating characteristic (ROC) curve cut-off values.

METHODS

Within 1 year of symptom onset, patients with SONK-selected treatment options, mainly based on severity of pain, chose either conservative treatment (n = 27 knees) or operative treatment (n = 27 knees). Knee and whole-leg radiographs, knee MRIs and bone mineral density scans of the lumbar spine, femoral neck and femoral condyles were obtained. The parameters measured were: (1) anatomical angle on whole-leg radiograph and (2) lesion size and medial meniscus extrusion on MRI.

RESULTS

The anatomical angle and lesion size in the sagittal section (depth) on MRI were markedly larger in the operative treatment group than those in the conservative treatment group. The anatomical angle and depth on MRI of SONK at Stages 1-3 were significantly different between groups, with odds ratios (95 % confidence intervals) of 1.16 (1.18-2.34) and 1.11 (1.01-1.23). One year after symptom onset, ROC curve cut-off value for anatomical angle was 180° and depth on MRI was 20 mm.

CONCLUSION

An anatomical angle >180° and depth >20 mm on MRI were predictive factors for a poorer prognosis 1 year after symptom onset in patients with SONK. Our results on radiographs and MRI provided a predictive prognosis for patients with SONK at the initial visit to their orthopaedic surgeons.

LEVEL OF EVIDENCE

III.

MR appearance of the temporal evolution and resolution of spontaneous osteonecrosis of the knee: a case report

Spontaneous osteonecrosis of the knee (SONK) is a feared condition of unknown cause, in its classic form appearing in the medial femoral condyle in middle-aged or elderly subjects. Diagnosis with radiography is notoriously difficult with a long latency before typical changes appear. Magnetic resonance imaging (MRI) is regarded as a diagnostic tool with the possibility to give an earlier diagnosis with improved chances for treatment. However, also with MRI there may be an initial diagnostic blind spot before typical changes appear. Little is known about the temporal evolution of the MRI changes. In the current case report, a case of SONK is reported where serial imaging with MRI was performed, from initial symptoms to eventual resolution after almost three years.

Can a biomimetic osteochondral scaffold be a reliable alternative to prosthetic surgery in treating late-stage SPONK?

BACKGROUND

This study aimed to assess the reliability of the Maioregen® biomimetic osteochondral scaffold (Finceramica Faenza SpA, Faenza, Italy) as a salvage and joint-preserving procedure in the treatment of late-stage osteonecrosis of the knee.

METHODS

Eleven active patients aged under 65years and presenting with clinical and radiological signs of SPONK were treated with Maioregen®. All were clinically evaluated pre-operatively and yearly thereafter for a minimum of two years. Subjective IKDC and Lysholm Knee Scale scores were used to assess clinical outcome. A VAS scale served to quantify pre-operative pain and post-operative pain. Activity levels were evaluated pre-operatively and at follow-up using the Tegner Activity Scale.

RESULTS

Subjective IKDC (40±15.0 to 65.7±14.8 (mean±SD)) and Lysholm Knee Scale (49.7±17.9 to 86.6±12.7 (mean±SD)) scores improved significantly from pre-operative evaluation (p<.01). VAS scores decreased from a pre-operative mean (±SD) of 6.3±2.5 to 1.6±2.7 at two years. The Tegner Activity Scale showed no significant differences between pre-injury and two-year follow-up. Two out of the 11 patients were symptomatic at 18months post implant and progressed to condylar collapse. These patients required total knee arthroplasty.

CONCLUSIONS

Use of a biomimetic scaffold can be a valid option in the surgical treatment of SPONK in relatively young active patients. Indeed, this surgical technique, originally developed for osteochondritis dissecans, has been found to give good clinical results at medium-term follow-up of late-stage osteonecrosis treatment and could postpone or even avoid the need for joint replacement procedures.

The importance of early diagnosis in spontaneous osteonecrosis of the knee - A case series with six year follow-up

BACKGROUND

Spontaneous osteonecrosis of the knee has an unknown aetiology. Management options include conservative, surgical and pharmacological interventions. The aim of this study was to report the experience of the authors in conservative management of SONK using non-operative measures by analysing the functional outcome and need for surgical intervention.

MATERIALS AND METHODS

All patients treated for SONK between 1st August 2001 and 1st April 2014 were retrospectively reviewed. Treatment consisted of touch-down weight bearing for around six weeks. MR imaging was evaluated for size of lesion, the condyles involved and the time taken for resolution. Tegner Activity Scale, VAS pain, Lysholm, WOMAC and IKDC scores were recorded at presentation and final follow-up (mean six years, range six months to 13years).

RESULTS

Forty cases were included; the mean age of the group was 55.3years and 67.5% were male. The medial femoral condyle was the most commonly affected (52.5%). A statistically significant improvement was reported in all functional outcome measures (p<0.001). Only one patient required arthroscopic surgical intervention and no patients required arthroplasty during the follow-up period.

CONCLUSION

Early stage spontaneous osteonecrosis of the knee can be managed successfully without surgery if diagnosed early. Thus early investigation of acute knee pain with MRI scanning is recommended.

When Is Osteonecrosis Not Osteonecrosis?: Adjudication of Reported Serious Adverse Joint Events in the Tanezumab Clinical Development Program

OBJECTIVE

Tanezumab, a monoclonal antibody against nerve growth factor, has demonstrated efficacy in clinical trials of chronic pain in osteoarthritis (OA) and chronic low back pain. Unexpected adverse events (AEs) described as osteonecrosis (ON) occurred during tanezumab development, leading the US Food and Drug Administration to impose a partial clinical hold for all indications except cancer pain. A blinded Adjudication Committee (AC) including orthopedic surgeons, rheumatologists, and an orthopedic pathologist reviewed and adjudicated joint-related AEs in the tanezumab clinical program.

METHODS

The AC adjudicated all reported cases of ON as well as cases of total joint replacements (TJRs) not reported as ON for which radiographs obtained within 9 months of the surgery were available. The AC prespecified categories for joint safety events including primary ON, worsening OA (rapid progression of OA [RPOA], normal progression of OA, insufficient information to distinguish between rapid and normal progression of OA), other, or insufficient information to distinguish between primary ON and worsening OA or another diagnosis.

RESULTS

The AC reviewed events in 249 of 386 patients with an investigator-reported AE of ON and/or a TJR. Two events were adjudicated as primary ON, 200 events were adjudicated as worsening OA (68 of which were classified as RPOA), 29 events had another diagnosis, 11 had insufficient information to distinguish primary ON from worsening OA, and 7 did not have committee member consensus.

CONCLUSION

Despite initial reports, tanezumab treatment was not associated with an increase in ON but was associated with an increase in RPOA. Higher doses of tanezumab, tanezumab administered with nonsteroidal antiinflammatory drugs, and preexisting subchondral insufficiency fractures were risk factors for RPOA in this cohort.

A Case of Spontaneous Osteonecrosis of the Knee with Early and Simultaneous Involvement of the Medial Femoral Condyle and Medial Tibial Plateau

Spontaneous osteonecrosis of the knee (SPONK) usually involves a single condyle, most often the medial femoral condyle (MFC). Involvement of the medial tibial plateau (MTP) is less common, occurring in about 2% of knees with SPONK. Early onset SPONK on the ipsilateral side of the medial compartment is very rare, with, to our knowledge, only four cases reported to date. We describe a very rare case of SPONK with early simultaneous development in the MFC and MTP. Serial plain radiographs and magnetic resonance imaging showed that SPONK in both condyles followed a similar progressive course. The pathological findings in these lesions were similar to those observed in subchondral insufficiency fractures.

Serious joint-related adverse events in randomized controlled trials of anti-nerve growth factor monoclonal antibodies

BACKGROUND

Reports of serious joint adverse events (AEs) due to osteonecrosis were noted during randomized placebo-controlled clinical trials of monoclonal antibodies to nerve growth factor (NGF), including tanezumab and fulranumab.

METHODS

All available medical records from subjects with reported cases of osteonecrosis, as well as records of subjects who underwent joint replacement during these studies, were reviewed by an independent adjudication committee that was established by each company; the committees were different for each company and included distinct individual experts. Cases were categorized as having definite osteonecrosis, normal or rapid progression of osteoarthritis (OA), another diagnosis or unable to determine the underlying diagnosis.

RESULTS

The vast majority of investigator reported cases of osteonecrosis were adjudicated as either normal or rapid progression of OA. Indeed, the syndrome of rapid progression of OA associated with chondrolysis and bone destruction appears to be a safety signal that is associated with not only increasing doses of anti-NGF antibodies but also concomitant therapy with nonsteroidal anti-inflammatory drugs.

CONCLUSIONS

These results have implications for future clinical trials of anti-NGF agents in OA and other painful conditions.

Medical treatment of osteonecrosis of the knee associated with thrombophilia-hypofibrinolysis

In 6 patients with stage II knee osteonecrosis, all 6 with thrombophilia and 4 with concurrent hypofibrinolysis, the authors prospectively determined whether anticoagulation with enoxaparin could prevent collapse and progression to osteoarthritis, ameliorate pain, and restore function. The 6 patients were treated with enoxaparin (40 to 60 mg/d for 3 or more months) as mandated by a US Food and Drug Administration-approved protocol. In post-enoxaparin prospective follow-up, patients were reassessed clinically every 4 to 6 months, and radiographs were obtained every year. The 6 patients followed up at 15.1, 7.5, 3.9, 2.25, 2, and 1 year, respectively. None progressed to joint collapse or severe osteoarthritis. Four became and remained asymptomatic at 2-, 3.9-, 7.5-, and 15.1-year follow-up, respectively. A fifth patient did not progress to collapse or severe osteoarthritis but had residual pain at 2.25-year follow-up. The sixth patient had no symptomatic benefit on enoxaparin but improved on rivaroxaban at 1-year follow-up. Two patients had recurrences of knee pain 1 and 4 years after their initial treatment with enoxaparin. One resolved after a second course of enoxaparin, and the other, with a second recurrence 1 year after the second course, resolved after a third course. Pretreatment, all 6 patients required canes, crutches, or wheelchairs, but after enoxaparin, no patient required them, and walking was unrestricted. Thrombophilia-hypofibrinolysis contributes to the pathogenesis of knee osteonecrosis. Thrombophilic-hypofibrinolytic patients with stage II knee osteonecrosis treated with enoxaparin have had no collapse or progression to severe osteoarthritis, and most have had resolution of pain and restoration of full function. This represents a major improvement compared with the natural history of untreated spontaneous knee osteonecrosis.

The Long-Term Clinical Outcomes Following Autogenous Bone Grafting for Large-Volume Defects of the Knee: 12- to 21-Year Follow-Up

OBJECTIVE

We report the long-term clinical outcomes of patients who underwent autogenous bone grafting of large-volume osteochondral defects of the knee due to osteochondritis dessicans (OCD) and osteonecrosis (ON). This is the companion report to one previous published on the biological response. We hypothesized that these grafts would integrate with host bone and the articular surface would form fibrocartilage providing an enduring clinical benefit.

DESIGN

Three groups (patients/knees) were studied: OCD without a fragment (n = 12/13), OCD with a partial fragment (n = 14/16), and ON (n = 25/26). Twenty-five of 52 patients were available for clinical follow-up between 12 and 21 years. Electronic medical records provided comparison clinical information. In addition, there were plain film radiographs, MRIs, plus repeat arthroscopy and biopsy on 14 patients.

RESULTS

Autogenous bone grafts integrated with the host bone. MRI showed soft tissue covering all the grafts at long-term follow-up. Biopsy showed initial surface fibrocartilage that subsequently converted to fibrocartilage and hyaline cartilage at 20 years. OCD patients had better clinical outcomes than ON patients. No OCD patients were asymptomatic at anytime following surgery. Half of the ON patients came to total knee replacement within 10 years.

CONCLUSIONS

Autogenous bone grafting provides an alternative biological matrix to fill large-volume defects in the knee as a singular solution integrating with host bone and providing an enduring articular cartilage surface. The procedure is best suited for those with OCD. The treatment for large-volume articular defects by this method remains salvage in nature and palliative in outcome.

Effect of ibandronate on spontaneous osteonecrosis of the knee: a randomized, double-blind, placebo-controlled trial

Based on this double-blind, placebo-controlled study, ibandronate has no beneficial effect on clinical and radiological outcome in patients with spontaneous osteonecrosis of the knee over and above anti-inflammatory medication.

INTRODUCTION

Observational studies suggest beneficial effects of bisphosphonates in spontaneous osteonecrosis (ON) of the knee. We investigated whether ibandronate would improve clinical and radiological outcome in newly diagnosed ON.

METHODS

In this randomized, double-blind, placebo-controlled trial, 30 patients (mean age, 57.3 ± 10.7 years) with ON of the knee were assigned to receive either ibandronate (cumulative dose, 13.5 mg) or placebo intravenously (divided into five doses 12 weeks). All subjects received additional treatment with oral diclofenac (70 mg) and supplementation with calcium carbonate (500 mg) and vitamin D (400 IU) to be taken daily for 12 weeks. Patients were followed for 48 weeks. The primary outcome was the change in pain score after 12 weeks. Secondary endpoints included changes in pain score, mobility, and radiological outcome (MRI) after 48 weeks.

RESULTS

At baseline, both treatment groups (IBN, n = 14; placebo, n = 16) were comparable in relation to pain score and radiological grading (bone marrow edema, ON). After 12 weeks, mean pain score was reduced in both ibandronate- (mean change, -2.98; 95% CI, -4.34 to -1.62) and placebo- (-3.59; 95% CI, -5.07 to -2.12) treated subjects (between-group comparison adjusted for age, sex, and osteonecrosis type, p = ns). Except for significant decrease in bone resorption marker (CTX) in ibandronate-treated subjects (p < 0.01), adjusted mean changes in all functional and radiological outcome measures were comparable between treatment groups after 24 and 48 weeks.

CONCLUSIONS

In patients with spontaneous osteonecrosis of the knee, bisphosphonate treatment (i.e., IV ibandronate) has no beneficial effect over and above anti-inflammatory medication.

The natural course of spontaneous osteonecrosis of the knee (SPONK): a 1- to 27-year follow-up of 40 patients

BACKGROUND AND PURPOSE

Spontaneous osteonecrosis of the knee (SPONK) is a painful lesion in the elderly, frequently leading to osteoarthritis and subsequent knee surgery. We evaluated the natural course and long-term consequences of SPONK in terms of need for major knee surgery.

METHODS

Between 1982 and 1988, 40 consecutive patients were diagnosed with SPONK. The short-term outcome has been reported previously (1991). After 1-7 years, 10 patients had a good radiographic outcome and 30 were considered failures, developing osteoarthritis. In 2012, all 40 of the patients were matched with the Swedish Knee Arthroplasty Register (SKAR) and their medical records were reviewed to evaluate the long-term need for major knee surgery.

RESULTS

At the 2012 review, 33 of the 40 patients had died. The mean follow-up time from diagnosis to surgery, death, or end of study was 9 (1-27) years. 17 of 40 patients had had major knee surgery with either arthroplasty (15) or osteotomy (2). All operated patients but 1 were in the radiographic failure group and had developed osteoarthritis in the study from 1991. 6 of 7 patients with large lesions (> 40% of the AP radiographic view of the condyle) at the time of the diagnosis were operated. None of the 10 patients with a lesion of less than 20% were ever operated.

INTERPRETATION

It appears that the size of the osteonecrotic lesion can be used to predict the outcome. Patients showing early signs of osteoarthritis or with a large osteonecrosis have a high risk of later major knee surgery.

Management of osteonecrosis of proximal tibia using trabecular osteonecrotic rods

Osteonecrosis of the knee is a well-described cause of acute knee pain. It can lead to significant functional impairment, rapid arthritic joint changes and subsequent collapse. Several hypotheses exist different treatment options are used ranging from conservative management to joint arthroplasty. The majority of cases involve the distal femoral condyle and to a much lesser extent the medial tibial plateau. We are presenting a rare case of osteonecrosis of the proximal tibia affecting the lateral tibial condyle in 44 years old Caucasian male which was treated successfully using osteonecrotic tantalum rods with 26 month follow-up.

The Biological Response following Autogenous Bone Grafting for Large-Volume Defects of the Knee: Index Surgery through 12 to 21 Years' Follow-up

OBJECTIVE

This report focuses on the biological events occurring at various intervals following autogenous bone grafting of large-volume defects of the knee joint's femoral condyle secondary to osteochondritis dissecans (OCD) or osteonecrosis (ON). It was hypothesized that the autogenous bone graft would integrate and the portion exposed to the articular surface would form fibrocartilage, which would endure for years.

METHODS

Between September 29, 1987 and August 8, 1994, there were 51 patients treated with autogenous bone grafting for large-volume osteochondral defects. Twenty-five of the 51 patients were available for long-term follow-up up to 21 years. Patient follow-up was accomplished by clinical opportunity and intentional research. Videotapes were available on all index surgeries for review and comparison. All had preoperative and postoperative plain film radiographs. Long-term follow-up included MRI up to 21 years. Second-look arthroscopy and biopsy were obtained on 14 patients between 8 weeks and 20 years.

RESULTS

Radiological assessment showed the autogenous bone grafts integrated with the host bone. The grafts retained the physical geometry of the original placement. MRI showed soft tissue covering the grafts in all cases at long-term follow-up. Interval biopsy showed the surface covered with fibrous tissue at 8 weeks and subsequently converted to fibrocartilage with hyaline cartilage at 20 years.

CONCLUSION

Autogenous bone grafting provides a matrix for large osteochondral defects that integrates with the host bone and results in a surface repair of fibrocartilage and hyaline cartilage that can endure for up to 20 years.

Cartilage repair and joint preservation: medical and surgical treatment options

BACKGROUND

Articular cartilage defects are most often caused by trauma and osteoarthritis and less commonly by metabolic disorders of the subchondral bone, such as osteonecrosis and osteochondritis dissecans. Such defects do not heal spontaneously in adults and can lead to secondary osteoarthritis. Medications are indicated for symptomatic relief. Slow-acting drugs in osteoarthritis (SADOA), such as glucosamine and chondroitin, are thought to prevent cartilage degeneration. Reconstructive surgical treatment strategies aim to form a repair tissue or to unload compartments of the joint with articular cartilage damage.

METHODS

In this article, we selectively review the pertinent literature, focusing on original publications of the past 5 years and older standard texts. Particular attention is paid to guidelines and clinical studies with a high level of evidence, along with review articles, clinical trials, and book chapters.

RESULTS

There have been only a few randomized trials of medical versus surgical treatments. Pharmacological therapies are now available that are intended to treat the cartilage defect per se, rather than the associated symptoms, yet none of them has yet been shown to slow or reverse the progression of cartilage destruction. Surgical débridement of cartilage does not prevent the progression of osteoarthritis and is thus not recommended as the sole treatment. Marrow-stimulating procedures and osteochondral grafts are indicated for small focal articular cartilage defects, while autologous chondrocyte implantationis mainly indicated for larger cartilage defects. These surgical reconstructive techniques play a lesser role in the treatment of osteoarthritis. Osteotomy near the knee joint is indicated for axial realignment when unilateral osteoarthritis of the knee causes axis deviation.

CONCLUSION

Surgical reconstructive techniques can improve joint function and thereby postpone the need for replacement of the articular surface with an artificial joint.

Bicondylar spontaneous osteonecrosis of the knee: A case report

Spontaneous osteonecrosis of the knee was originally described as a distinct disorder in 1968. Characteristic imaging findings and distinctive demographic and clinical factors help distinguish this disease from other osteonecrotic conditions, with which it can be confused. This report presents a rare, atypical case of bicondylar spontaneous osteonecrosis of the knee in a young patient, and highlights the importance of a clear understanding of the clinical and radiographic characteristics of this condition to accurately diagnose and treat it when evaluating osteonecrotic lesions of the knee.