Orthopedics Today Grand Rounds

A 35-year-old man with pain after ACL reconstruction, meniscal repair, and partial meniscectomy

A healthy, active 35-year-old man presented 5 days following a non-contact right knee injury sustained while playing soccer. He described planting his foot, feeling his knee “shift” and hearing two loud pops, which caused him to fall. The man was initially evaluated at an outside institution where radiographs of the right knee were deemed negative for fracture. He was told to follow up with an orthopedic surgeon for further evaluation.

The patient is a local firefighter who has no previous medical or surgical history and does not take any medications other than daily multivitamins. He denies the use of alcohol, tobacco or recreational drugs. Of note, he endorses a history of a previous contralateral knee injury that was reportedly diagnosed as a partial ACL tear and was managed nonoperatively.

On physical examination, the patient’s right knee had a 2+ to 3+ knee effusion. Range of motion was 3° to 80°. He had positive Lachman and anterior drawer tests, but the posterior drawer test was negative. The patient demonstrated slight instability to valgus stress at 0° and 30° but with an excellent endpoint. Varus stress testing was negative. He endorsed tenderness to palpation over the lateral joint line and medial femoral epicondyle. His contralateral limb examination was unremarkable. He was fully neurovascularly intact in both lower extremities.

Figure 1. A preoperative MRI demonstrates the initial injury with disruption of the ACL (a) and a medial meniscal injury (b).
Figure 2. The postoperative MRI shows medial compartment meniscal deficiency (a) and medial compartment overload with increased signal in proximal medial tibia (b).
Figure 3. Long-leg alignment films demonstrate varus alignment.
Figure 4. An arthroscopic photo shows medial compartment meniscal deficiency and grade 2 articular cartilage changes.

Source: Sommer Hammoud, MD

A non-contrast MRI study was done (Figure 1). It showed a complete ACL tear with associated osteochondral signal consistent with a traumatic pivot shift. Both collateral ligaments were intact but with adjacent signal consistent with sprains. Tears were noted in both the medial and lateral meniscus. No additional significant pathology was visualized.

After appropriate counseling, the patient elected to proceed with ACL reconstruction with bone-patellar tendon-bone allograft and concomitant medial and lateral meniscus surgery. Intra operatively, there was a complete radial tear of the posterior horn of the lateral meniscus that was amenable to an all-inside repair. Unfortunately, the medial meniscal tear was complex involving the body and posterior horn. It required partial meniscectomy of about 50% of the body and posterior horn involving the white-white and the red-white zone. The root was also avulsed and a meniscal root repair of the remaining peripheral rim tissue was performed.

The patient’s initial postoperative course was unremarkable with appropriate achievement of range of motion goals and stable physical exam. However, at the 4.5-month follow-up visit, he reported discomfort over the medial aspect of his knee during exercises, particularly squats. He denied associated instability or giving way. On exam, he was noted to have medial joint line tenderness and a negative Lachman exam. At his 6-month follow-up visit, the patient continued to endorse medial knee discomfort with exercise, as well as occasional clicking and catching. A new MRI to reassess his graft and menisci demonstrated an intact ACL graft but it suggested medial meniscal deficiency with increased signal in the proximal tibia consistent with compartment overload (Figure 2). Tthis was initially managed with physical therapy and strengthening.

At the 9-month postoperative visit, the patient continued to endorse medial knee pain with jogging and increased activity, which had worsened since the symptoms initially developed. His exam continued to suggest a stable ACL graft, but there was tenderness to palpation along the medial joint line. Long-leg alignment radiographs were performed which demonstrated a plumb line that fell through the medial tibial spine indicating slight varus alignment (Figure 3). Given the patient’s continued medial joint line pain, the previous concern about possible re tear of the medial meniscus on MRI and an extensive discussion of treatment options, the patient elected to proceed with diagnostic arthroscopy.

Diagnostic arthroscopy confirmed an intact ACL graft with appropriate neovascularization. The lateral compartment contained a healed meniscal repair and demonstrated grade 1 tibiofemoral articular cartilage changes. The medial compartment contained a bird beak-type tear that required revision partial medial meniscectomy and demonstrated grade 2 tibiofemoral articular cartilage changes as seen in the final arthroscopic view of the medial compartment (Figure 4). Postoperatively, the patient more a medial unloader brace that produced excellent pain relief. He noted that after removing the brace, he immediately had return of medial knee pain with activity.

What is your diagnosis?
See answer on the next page.

Post-meniscectomy medial compartment overload in pre-existing varus alignment

After the patient’s ACL reconstruction, lateral meniscal repair and partial medial meniscectomy, he developed persistent pain localized to the medial compartment. Postoperative long-leg alignment films suggested a varus alignment, and postoperative MRI confirmed a competent ACL graft but suggested recurrent medial meniscal injury. Second-look arthroscopy confirmed these findings, which required additional medial meniscectomy, and early articular cartilage degenerative changes in the medial compartment. Furthermore, the patient’s symptoms responded dramatically to a medial unloader brace after second-look arthroscopy suggesting the patient’s pre-existing, but previously asymptomatic, varus alignment was responsible for the persistent medial knee symptoms. After a discussion about operative and nonoperative treatment options, the patient underwent medial, opening wedge, high tibial osteotomy (HTO) and plain radiographs were taken postoperatively (Figure 5).

Discussion

Meniscus-deficient knees are subject to higher contact stresses across the joint. Studies have shown a positive linear relationship between contact stresses across the knee and the amount of meniscus removed during meniscectomy resulting in post-meniscectomy tibial malalignment. Due to the risk of worsening degenerative changes associated with malalignment, procedures like HTO were developed to offload the affected portion of the joint by correcting joint alignment.

As a result, HTO has been indicated for correcting symptomatic unicompartmental knee arthritis associated with tibial malalignment as was seen in this patient. HTO aims to recreate a more mechanically favorable environment within the knee by restoring or overcorrecting proper tibial alignment and redistributing pathologic contact stresses. While this procedure is most commonly used to address varus deformity with medial-sided knee pain in young active individuals for whom arthroplasty would be otherwise contraindicated, good results have been reported with varus-inducing HTOs for valgus alignment in patients with lateral-sided symptoms.

Patients who are indicated for HTO following a meniscectomy typically present with knee pain that correlates with the side of the knee that is meniscus-deficient. Radiographs in these patients typically demonstrate unicompartmental degenerative changes and mechanical axis deviation, which can be assessed on full-length weight-bearing radiographs by drawing a plumb line from the center of the femoral head to the center of the talar dome. The plumb line should fall on or just lateral to the medial tibial spine, as described by Thomas W. Dugdale, MD, and colleagues. Otherwise, a diagnosis of malalignment can be made. Based on the resulting alignment, a varus or valgus HTO may be indicated.

Figure 5. Anteroposterior (a) and lateral (b) plain radiographs depict the patient’s right lower extremity after HTO.

Valgus-producing HTOs are done in patients with isolated varus malalignment that results in symptomatic medial compartment degenerative changes, such as this patient. Restoration of proper tibial alignment can be achieved by a medial opening-wedge, a lateral closing-wedge or a dome osteotomy. Although the lateral closing-wedge HTO has historically been the most common approach for addressing this pathology, the medial opening-wedge osteotomy, which was performed in our patient, preserves the posterior slope and avoids the proximal tibiofibular joint. The best results for this procedure are attained when the HTO overcorrects the anatomic axis of the knee to 10° valgus from less than 10° varus. In contrast, patients with valgus alignment and associated symptomatic lateral compartment degenerative changes may be indicated for varus-producing HTO.

This case highlights the potential sequela associated with partial or total meniscectomy and the importance of considering lower limb alignment as a potential etiology for post-meniscectomy symptoms. As in the patient presented herein, even minimal or moderate pre-existing malalignment may become symptomatic after subtotal meniscectomy. Although HTO can effectively extend the life of the native knee in patients with symptomatic post-meniscectomy malalignment, all attempts should be made at repairing the meniscus whenever possible.

Disclosures: Hammoud, Paziuk and Rogalski report no relevant financial disclosures.

A healthy, active 35-year-old man presented 5 days following a non-contact right knee injury sustained while playing soccer. He described planting his foot, feeling his knee “shift” and hearing two loud pops, which caused him to fall. The man was initially evaluated at an outside institution where radiographs of the right knee were deemed negative for fracture. He was told to follow up with an orthopedic surgeon for further evaluation.

The patient is a local firefighter who has no previous medical or surgical history and does not take any medications other than daily multivitamins. He denies the use of alcohol, tobacco or recreational drugs. Of note, he endorses a history of a previous contralateral knee injury that was reportedly diagnosed as a partial ACL tear and was managed nonoperatively.

On physical examination, the patient’s right knee had a 2+ to 3+ knee effusion. Range of motion was 3° to 80°. He had positive Lachman and anterior drawer tests, but the posterior drawer test was negative. The patient demonstrated slight instability to valgus stress at 0° and 30° but with an excellent endpoint. Varus stress testing was negative. He endorsed tenderness to palpation over the lateral joint line and medial femoral epicondyle. His contralateral limb examination was unremarkable. He was fully neurovascularly intact in both lower extremities.

Figure 1. A preoperative MRI demonstrates the initial injury with disruption of the ACL (a) and a medial meniscal injury (b).
Figure 2. The postoperative MRI shows medial compartment meniscal deficiency (a) and medial compartment overload with increased signal in proximal medial tibia (b).
Figure 3. Long-leg alignment films demonstrate varus alignment.
Figure 4. An arthroscopic photo shows medial compartment meniscal deficiency and grade 2 articular cartilage changes.

Source: Sommer Hammoud, MD

PAGE BREAK

A non-contrast MRI study was done (Figure 1). It showed a complete ACL tear with associated osteochondral signal consistent with a traumatic pivot shift. Both collateral ligaments were intact but with adjacent signal consistent with sprains. Tears were noted in both the medial and lateral meniscus. No additional significant pathology was visualized.

After appropriate counseling, the patient elected to proceed with ACL reconstruction with bone-patellar tendon-bone allograft and concomitant medial and lateral meniscus surgery. Intra operatively, there was a complete radial tear of the posterior horn of the lateral meniscus that was amenable to an all-inside repair. Unfortunately, the medial meniscal tear was complex involving the body and posterior horn. It required partial meniscectomy of about 50% of the body and posterior horn involving the white-white and the red-white zone. The root was also avulsed and a meniscal root repair of the remaining peripheral rim tissue was performed.

The patient’s initial postoperative course was unremarkable with appropriate achievement of range of motion goals and stable physical exam. However, at the 4.5-month follow-up visit, he reported discomfort over the medial aspect of his knee during exercises, particularly squats. He denied associated instability or giving way. On exam, he was noted to have medial joint line tenderness and a negative Lachman exam. At his 6-month follow-up visit, the patient continued to endorse medial knee discomfort with exercise, as well as occasional clicking and catching. A new MRI to reassess his graft and menisci demonstrated an intact ACL graft but it suggested medial meniscal deficiency with increased signal in the proximal tibia consistent with compartment overload (Figure 2). Tthis was initially managed with physical therapy and strengthening.

At the 9-month postoperative visit, the patient continued to endorse medial knee pain with jogging and increased activity, which had worsened since the symptoms initially developed. His exam continued to suggest a stable ACL graft, but there was tenderness to palpation along the medial joint line. Long-leg alignment radiographs were performed which demonstrated a plumb line that fell through the medial tibial spine indicating slight varus alignment (Figure 3). Given the patient’s continued medial joint line pain, the previous concern about possible re tear of the medial meniscus on MRI and an extensive discussion of treatment options, the patient elected to proceed with diagnostic arthroscopy.

Diagnostic arthroscopy confirmed an intact ACL graft with appropriate neovascularization. The lateral compartment contained a healed meniscal repair and demonstrated grade 1 tibiofemoral articular cartilage changes. The medial compartment contained a bird beak-type tear that required revision partial medial meniscectomy and demonstrated grade 2 tibiofemoral articular cartilage changes as seen in the final arthroscopic view of the medial compartment (Figure 4). Postoperatively, the patient more a medial unloader brace that produced excellent pain relief. He noted that after removing the brace, he immediately had return of medial knee pain with activity.

What is your diagnosis?
See answer on the next page.

PAGE BREAK

Post-meniscectomy medial compartment overload in pre-existing varus alignment

After the patient’s ACL reconstruction, lateral meniscal repair and partial medial meniscectomy, he developed persistent pain localized to the medial compartment. Postoperative long-leg alignment films suggested a varus alignment, and postoperative MRI confirmed a competent ACL graft but suggested recurrent medial meniscal injury. Second-look arthroscopy confirmed these findings, which required additional medial meniscectomy, and early articular cartilage degenerative changes in the medial compartment. Furthermore, the patient’s symptoms responded dramatically to a medial unloader brace after second-look arthroscopy suggesting the patient’s pre-existing, but previously asymptomatic, varus alignment was responsible for the persistent medial knee symptoms. After a discussion about operative and nonoperative treatment options, the patient underwent medial, opening wedge, high tibial osteotomy (HTO) and plain radiographs were taken postoperatively (Figure 5).

Discussion

Meniscus-deficient knees are subject to higher contact stresses across the joint. Studies have shown a positive linear relationship between contact stresses across the knee and the amount of meniscus removed during meniscectomy resulting in post-meniscectomy tibial malalignment. Due to the risk of worsening degenerative changes associated with malalignment, procedures like HTO were developed to offload the affected portion of the joint by correcting joint alignment.

As a result, HTO has been indicated for correcting symptomatic unicompartmental knee arthritis associated with tibial malalignment as was seen in this patient. HTO aims to recreate a more mechanically favorable environment within the knee by restoring or overcorrecting proper tibial alignment and redistributing pathologic contact stresses. While this procedure is most commonly used to address varus deformity with medial-sided knee pain in young active individuals for whom arthroplasty would be otherwise contraindicated, good results have been reported with varus-inducing HTOs for valgus alignment in patients with lateral-sided symptoms.

Patients who are indicated for HTO following a meniscectomy typically present with knee pain that correlates with the side of the knee that is meniscus-deficient. Radiographs in these patients typically demonstrate unicompartmental degenerative changes and mechanical axis deviation, which can be assessed on full-length weight-bearing radiographs by drawing a plumb line from the center of the femoral head to the center of the talar dome. The plumb line should fall on or just lateral to the medial tibial spine, as described by Thomas W. Dugdale, MD, and colleagues. Otherwise, a diagnosis of malalignment can be made. Based on the resulting alignment, a varus or valgus HTO may be indicated.

Figure 5. Anteroposterior (a) and lateral (b) plain radiographs depict the patient’s right lower extremity after HTO.
PAGE BREAK

Valgus-producing HTOs are done in patients with isolated varus malalignment that results in symptomatic medial compartment degenerative changes, such as this patient. Restoration of proper tibial alignment can be achieved by a medial opening-wedge, a lateral closing-wedge or a dome osteotomy. Although the lateral closing-wedge HTO has historically been the most common approach for addressing this pathology, the medial opening-wedge osteotomy, which was performed in our patient, preserves the posterior slope and avoids the proximal tibiofibular joint. The best results for this procedure are attained when the HTO overcorrects the anatomic axis of the knee to 10° valgus from less than 10° varus. In contrast, patients with valgus alignment and associated symptomatic lateral compartment degenerative changes may be indicated for varus-producing HTO.

This case highlights the potential sequela associated with partial or total meniscectomy and the importance of considering lower limb alignment as a potential etiology for post-meniscectomy symptoms. As in the patient presented herein, even minimal or moderate pre-existing malalignment may become symptomatic after subtotal meniscectomy. Although HTO can effectively extend the life of the native knee in patients with symptomatic post-meniscectomy malalignment, all attempts should be made at repairing the meniscus whenever possible.

Disclosures: Hammoud, Paziuk and Rogalski report no relevant financial disclosures.

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