Postarthroscopy Osteonecrosis of the Knee: Current Concepts

Can Knee Arthroscopy Be Considered Entirely Safe for Patients Over 50 Years Old With no Risk of Osteonecrosis? Case Series and Literature Review on Post-Artrhoscopy Osteonecrosis of the Knee (PAONK)

OBJECTIVE

Although post-arthroscopy osteonecrosis of the knee is well-documented in the literature, its etiology and prognosis remain unclear. The purpose of this study is to present a group of individuals who experienced avascular necrosis following knee arthroscopy, to examine the factors leading to this condition and assess the outcomes of treatment, as well as to perform a literature review on the subject.

METHODS

We retrospectively studied patients between January 2015 and March 2024 who had developed knee osteonecrosis following a standard arthroscopic procedure for treating meniscal tears. All adult patients with isolated meniscus tears and grade 2 or less chondral lesions were included. Patients with evidence of bone edema on MRI performed 4-6 weeks after the onset of preoperative symptoms were not included in the study. The Knee injury and Osteoarthritis Outcome Score (KOOS) was used as an outcome measure. A correlation analysis was performed to explore the degree of association between variables, with significance set at p < 0.05.

RESULTS

Eight patients out of 974 arthroscopies met the inclusion criteria. There was one woman and seven men (mean age 57 [range: 51-71]). The lesions noted at arthroscopy included seven medial meniscus tears that were treated with excision and one lateral meniscal tear that was treated with suture repair and still developed osteonecrosis. None of them were traumatic while all patients had early degenerative changes in the compartment of interest.

CONCLUSIONS

Osteonecrosis should be suspected in older patients experiencing worsening symptoms following knee arthroscopy for degenerative meniscus tears and partial meniscectomy. Increased age, a higher BMI, and a delayed diagnosis appear to be associated with more severe disease progression and the need for operative treatment.

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.

Extrusion of the medial meniscus is a potential predisposing factor for post-arthroscopy osteonecrosis of the knee

Background

Post-arthroscopic osteonecrosis of the knee (PAONK) is a rare condition. No studies have analyzed the relationship between the meniscus extrusion and PAONK. The purpose of this retrospective study is to test a hypothesis that the degree of the medial meniscus (MM) extrusion might be significantly greater in the knees with PAONK than in the matched control knees both before and after the meniscectomy.

Methods

Ten knees with PAONK were detected out of a total of 876 knees which had undergone arthroscopic partial meniscectomy of the MM. Ten matched control knees were randomly selected out of the remaining 866 knees without PAONK. The clinical data of these 20 patients were retrospectively collected from the medical records. To evaluate the location of the menisci on the joint line, Extrusion width and Inner width were defined on a coronal section of magnetic resonance imaging (MRI). The intra- and inter-rater reliability was evaluated by calculating the intra- and inter-class coefficients. Statistical comparisons between the 2 groups were made using the 3 non-parametric tests.

Results

Before the meniscectomy, the Extrusion width of the MM (mean 4.7 ± 1.4 mm) was significantly greater than that (3.0 ± 1.3 mm) in the Control group (P = 0.0195). In the MRI taken in a range from 3 to 50 weeks after the meniscectomy, the Extrusion width of the MM (5.9 ± 1.1 mm) in the PAONK group was significantly greater than that (3.4 ± 1.4 mm) in the Control group (P = 0.0009), and the Inner width of the MM (0.6 ± 1.7 mm) in the PAONK group was significantly less than that (3.9 ± 1.0 mm) in the Control group (P = 0.0001).

Conclusion

A significant relationship was found between the degree of the MM extrusion and the onset of PAONK. This study suggested that the extrusion of the MM is a potential predisposing factor for PAONK.

Post-arthroscopic osteonecrosis of the knee: A case report and literature review

Post-arthroscopic osteonecrosis is a rare complication of arthroscopic surgery. The present study reported on a case of knee osteonecrosis after arthroscopic surgery. The patient, an 81-year-old male, presented with left knee pain and limited range of motion without any history of trauma. MRI revealed medial meniscus tear. Medial partial meniscectomy was performed using arthroscopy. The pain was found to be relieved due to the operation. However, there was an aggravation of pain after two months post-operatively. X-ray revealed that the subchondral bone in the medial femoral condyle (MFC) had collapsed. MRI revealed a large area of bone marrow edema in the MFC with cartilage delamination and subchondral flattening. Considering the age of the patient and the large area of bone necrosis, total knee arthroplasty was performed. At the 1-year follow-up, the Knee Society Knee Score improved from 44 points pre-operatively to 90 points and the Knee Society Functional Score was elevated from 35 to 90 points. Patient-reported outcome measures were assessed in the form of the Oxford Knee Score, which was 16. Furthermore, previous case reports of post-arthroscopic osteonecrosis were reviewed and the clinical and radiographic features, as well as the treatment, were summarized. If the patient complains of persistent and worsening pain after arthroscopy, particularly in elderly osteoporotic patients with meniscal tears or chondral lesions, the possibility of post-arthroscopic knee osteonecrosis should be considered. Diagnosis and treatment at the early stages are likely to be beneficial for the outcome.

Effect of Lower Limb Alignment in Medial Meniscus-Deficient Knees on Tibiofemoral Contact Pressure

Background:

Degenerative medial meniscal tears and subsequent partial meniscal resection compromise meniscal function and lead to an overload of the medial compartment. In addition, lower limb alignment plays a key role in load distribution between the medial and lateral knee compartments, and varus alignment is a potential risk factor for medial osteoarthritis.

Purpose/Hypothesis:

The purpose of this biomechanical study was to investigate the effect of valgus and varus alignment on peak pressure and contact area in knees with concomitant horizontal medial meniscal tears and subsequent leaflet resection. It was hypothesized that varus alignment in combination with meniscal loss leads to the highest peak pressure within the medial compartment.

Study Design:

Controlled laboratory study.

Methods:

Six fresh-frozen human cadaveric knees were axially loaded using a 1000-N compressive load in full extension with the mechanical axis rotated to intersect the tibial plateau at 40%, 45%, 50%, 55%, and 60% of its width (TPW) to simulate varus and valgus alignment. Tibiofemoral peak contact pressure and contact area of the medial and lateral compartments were determined using pressure-sensitive foils in each of 4 different meniscal conditions: intact, 15-mm horizontal tear of the posterior horn, inferior leaflet resection, and resection of both leaflets.

Results:

The effect of alignment on peak pressure (normalized to the neutral axis) within the medial compartment in cases of an intact meniscus was measured as follows: varus shift resulted in a mean increase in peak pressure of 18.5% at 45% of the TPW and 37.4% at 40% of the TPW, whereas valgus shift led to a mean decrease in peak pressure of 8.7% at 55% of the TPW and 23.1% at 60% of the TPW. Peak pressure changes between the intact meniscus and resection within the medial compartment was less in valgus-aligned knees (0.21 MPa at 60% TPW, 0.59 MPa at 50% TPW, and 0.76 MPa at 40% TPW). Contact area was significantly reduced after partial meniscal resection in the neutral axis (intact, 553.5 ± 87.6 mm²; resection of both leaflets, 323.3 ± 84.2 mm²; P < .001). This finding was consistent in any alignment.

Conclusion:

Both partial medial meniscal resection and varus alignment led to an increase in medial compartment peak pressure. Valgus alignment prevented medial overloading by decreasing contact pressure even after partial meniscal resection. A horizontal meniscal tear did not influence peak pressure and contact area even in varus alignment.

Clinical Relevance:

As a clinical consequence, partial meniscal resection should be avoided to maintain the original biomechanical behavior, and the mechanical axis should be taken into account if partial meniscectomy is necessary.

[Analysis of medial unicompartmental knee arthroplasty for patients with spontaneous osteonecrosis of the knee]

Objective

To analyse the effectiveness of unicompartmental knee arthroplasty (UKA) for the patients with spontaneous osteonecrosis of the knee (SONK).

Methods

Between January 2012 and December 2016, 31 patients with SONK was admitted and treated with medial UKA. All patients were examined by both plain radiography and magnetic resonance images. The patients were composed of 5 men and 26 women with an average age of 64.3 years (range, 48-79 years), and with 16 left joints and 15 right joints. The average disease duration was 14.7 months (range, 6-26 months). Preoperative visual analogue scale (VAS) was 6.00±1.15, Hospital for Special Surgery (HSS) score was 55.77±11.03, and knee range of motion (ROM) was (114.68±10.40)°. The imaging examinations showed that all the lesions were located in the medial compartment of the knee joint and there were 19 patients with Aglietti stage Ⅳ and 12 patients with Aglietti stage Ⅴ. Preoperative femorotibial angle (FTA) was (177.39±1.63)° and posterior tibial slope (PTS) was (84.05±1.39)°.

Results

All the incisions healed by first intention. All patients were followed up 14-46 months (mean, 25 months). At last follow-up, VAS score was 2.06±0.72 and HSS score was 86.45±3.67, which both improved significantly when compared with preoperative scores ( t=22.73, P=0.00; t=-14.72, P=0.00). ROM was (118.06±3.80)° with no significant difference when compared with preoperative ROM ( t=-1.78, P=0.08). The X-ray films showed there was no severe adverse events, such as periprosthetic infection, aseptic loosening, bearing dislocation, and so on. At last follow- up, PTS was (85.30±1.19)° with significant difference compared with preoperative one ( t=-4.07, P=0.00); while FTA was (177.51±1.98)° with no significant difference when compared with preoperative FTA ( t=-0.38, P=0.71).

Conclusion

UKA may be an optional management for SONK with minimally invasive, bone-preserving, and rapid recovery.