There is no consensus on the best treatment for anterior cruciate ligament hypoplasia or aplasia. To our knowledge, no comparative study between operative and conservative treatment of this condition has ever been performed. Conservative treatment is a viable alternative to surgery for ACL aplasia. Two siblings were examined at our outpatient clinic. The male patient underwent bilateral ACL reconstruction, while his sister was treated conservatively. Our results show a worse long-term outcome for the operative patient. At her last follow-up, the female patient treated conservatively showed subjective improvement in stability and gait. A review of the literature shows inconsistent outcomes after reconstruction in contrast to reports with cruciate ligament agenesis that did not undergo reconstruction with acceptable to good outcomes. Cruciate reconstruction should be reserved for cases of impaired articular instability, objectively manifest in the frequency of giving-way episodes. Treatment depends on the patient’s condition and expectations. Surgery should therefore only be suggested after proper patient counseling.
Hypoplasia or aplasia of the cruciate ligaments is a rare congenital condition, with a prevalence of 0.017 per 1000 live births [
The pathophysiology of cruciate ligament aplasia and its impact on daily life are not well understood, and clinical management remains controversial. To our knowledge, no comparative study between operative and conservative treatment of cruciate ligament aplasia in siblings has been performed. The purpose of this case report is to review our experience of the treatment of two siblings with a bilateral symptomatic congenital absence of the anterior cruciate ligament (ACL). We will also present a review of the literature.
A 6-year-old male patient was evaluated at our center for a history of left knee pain after a sprain. Physical examination revealed a limping gait intra-articular swelling and a bilateral anterior instability of both knee joints. The modified Lysholm score was 55 on the left knee and 66 on the right knee. Standard radiographs showed hypoplasia of the tibial intercondylar eminence and the femoral intercondylar notch (Figures
Plain, anteroposterior (a) and lateral (b) radiographs of a 6-year-old male patient’s left knee showing hypoplasia of the tibial intercondylar eminence and of the femoral intercondylar notch.
Preoperative MRI of the left knee of the patient from Figure
Preoperative MRI (sagittal (a), coronal (b), and transverse (c) views) of the right knee of the patient from Figures
The patient underwent arthroscopic evaluation that confirmed an aplasia of the ACL (Manner II [
The autologous patellar tendon graft was harvested without a bony segment. The range of motion was tested up to a flexion and extension of 90°/0°/0°. At this point the stalked graft was passed from Gerdy’s tubercle behind the lateral collateral ligament and the popliteal tendon and sutured to the lateral femoral condyle. A splint with a flexion of 20° was adapted and the leg was passively mobilized for four weeks. Full weight-bearing was started at eight postoperative weeks. Physical therapy was prolonged for 5 months because of a moderate limitation in knee extension which caused a limping gait. Nine months after the operation of the left knee the patient was free of symptoms. The operation on the right knee consisted of a diagnostic arthroscopy with reconstruction of the ACL with autologous semitendinosus and gracilis tendon grafting along with epiphyseal femoral and transepiphyseal tibial fixation. A MacIntosh lateral ligamentoplasty was performed at the same time.
Forty months after the first operation, the patient was not impaired in his daily activities but displayed bilateral laxity on physical examination. The patient suffered from frequent episodes of his left knee giving way, with associated swelling and tenderness. Bilateral MRIs (Figures
Bilateral clinical outcomes of both patients at their last follow-up.
Last follow-up | Case |
Case |
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Right | Left | Right | Left | |
Modified Lysholm score | 53 | 49 | 91 | 91 |
Femoral axis | 5° valgus | 5° valgus | 0° | 0° |
ROM F/E | 150/0/5° | 150/0/5° | 150/0/5° | 150/0/5° |
Anterior drawer test (rolimeter mm) | 12 | 18 | 10 | 8 |
Lachmann test | III | III | I | I |
Pivot shift | pos | pos | neg | neg |
Posterior drawer test | pos | neg | neg | neg |
Varus instability 0° (mm) | 10 | 5 | <5 | <5 |
Valgus instability 0° (mm) | 5 | 5 | <5 | <5 |
Varus instability 30° (mm) | 15 | 5 | <5 | <5 |
Valgus instability 30° (mm) | 15 | 15 | 10 | 5 |
Postoperative MRI (sagittal (a), coronal (b), and transverse (c) views) of the left knee of the patient from Figures
Postoperative MRI (sagittal (a), coronal (b), and transverse (c) views) of the right knee of the patient from Figures
The 15-year-old girl sister of the first patient was also examined at our outpatient clinic for occasional knee pain, swelling, and functional instability of both knees under pivot stress. Her symptoms started 1 year earlier and were present inconsistently during school physical exercise. Her modified Lysholm score was estimated to be 52 on both knees. Both knees had a positive anterior drawer test. Bilateral MRIs showed complete agenesis of the ACL but a normal PCL (Figures
MRI (sagittal (a), coronal (b), and transverse (c) views) of the right knee of a 15-year-old female patient shows complete agenesis of the ACL and a normal PCL.
MRI (sagittal (a), coronal (b), and transverse (c) views) of the left knee of the patient from Figure
Modified MacIntosh procedure for ACL reconstruction.
At the 2-year follow-up, the patient showed improved subjective stability and gait. The findings are summarized in Table
The first report of congenital cruciate ligament agenesis was published by Giorgi [
Manner et al. [
The clinical symptoms of cruciate ligament aplasia can range from completely asymptomatic [
The first report of ACL agenesis treated with autologous reconstruction was presented by Katz et al. in 1967 [
Kaelin et al. [
Dejour et al. [
The study by Gabos et al. [
Steckel et al. [
Knorr et al. [
Knorr et al. [
Bedoya et al. [
A study by Sonn and Caltoum [
One of the largest series on congenital cruciate ligament agenesis was reported by Thomas et al. [
Past reports in the literature of ACL aplasia are listed and described in Table
Summary of published studies regarding the treatment of ACL aplasia.
Author | Publication year | Number of knees | Description |
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Katz et al. | 1967 | 5 | ACL agenesis treated with autologous reconstruction with good operative outcomes in all cases. |
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Thomas et al. | 1985 | 12 | Congenital cruciate ligament agenesis: half of the patients were asymptomatic, while the other half admitted to their knee giving way more than once a week. All patients underwent arthroscopy, but no ACL reconstruction was performed. |
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Kaelin et al. | 1986 | 6 | Documentation of arthroscopy in six knees with ligamentous aplasia. |
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Dejour et al. | 1990 | 1 | Bilateral ligamentous aplasia treated bilaterally with surgery. There was no subjective instability. However, there was persistent pain in the second operated knee. |
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de Ponti et al. | 2001 | 1 | Bilateral ACL agenesis is associated with tibial or fibular dysplasia, subluxation, or dislocation of the patella, ligament hyperlaxity. |
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Gabos et al. | 2005 | 4 | Four patients who underwent tendon allograft ACL reconstructions. After a follow-up of 31 months, only one case of a 10-degree extension occurred. Laxity was clinically and subjectively improved in all patients, with a mean Lysholm score of 81. |
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Frikha et al. | 2005 | 8 knees in the same family | Congenital cruciate ligament agenesis is autosomal, dominant. |
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Steckel et al. | 2005 | 1 | Lateral discoid meniscus is associated with ACL aplasia. |
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Manner et al. | 2006 | 34 | Bilateral ACL agenesis is associated with proximal focal femoral deficiency, congenital talipes equinovarus, fibular hemimelia. |
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Knorr et al. | 2006 | 1 | Case of ACL agenesis and a hypoplastic medial meniscus treated with Clochville ACL reconstruction. At the 5-year follow-up, the patient was asymptomatic, with clinically improved stability. |
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Lee et al. | 2006 | 1 | Case of ACL agenesis and a hypoplastic PCL treated with notchplasty and transtibial single-bundle ACL reconstruction. At the 6-month follow-up, improved clinical stability without range of motion restriction was observed. |
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Roth et al. | 2010 | 3 | Bilateral ACL agenesis is associated with agenesis or hypoplasia of the patella, hip dysplasia, or dislocation. |
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Bedoya et al. | 2014 | 1 | Case of ACL agenesis treated with surgery. |
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Sonn and Caltoum | 2014 | 1 | Male monozygotic twins with symptomatic ACL agenesis. Both underwent ligament reconstruction with a patellar graft. At 32 postoperative months, both patients had good clinical knee stability. |
Many other reports show acceptable to good outcomes of patients with cruciate ligament agenesis who do not undergo reconstruction [
In the first months after surgery, the stability of the boy’s knees objectively improved. However, after a few years his instability recurred, with symptoms of giving way and poor functional outcome. His sister had a better result with muscle reinforcement through physical therapy, which yielded long-lasting benefits. The number of cases in our study was limited by the rarity of the disease.
Here, we show an attempt to stabilize both knees in a 6-year-old boy with ACL aplasia. The risk of surgical failure was high from the onset, due to the fact that the graft could not follow the patient’s skeletal growth. Moreover valgus deformities of the knee, leg length discrepancies, and hip or ankle dysplasia are frequently associated with cruciate ligament aplasia. A surgical approach is also reasonable if epiphyseal closure is not yet obtained but should be attentively considered. A study of Holwein et al. [
Based on our literature review, most symptomatic cases of ligamentous aplasia start with a low-grade trauma or sprain and end in muscular imbalance. A long-lasting symptom history is not necessarily the rule in this pathology. Sufficient time should be allocated to assess the benefits of physical rebalancing before surgical reconstruction is considered. We agree with the statements of de Ponti et al. [
Our analysis of the literature illustrates the current disagreement on the appropriate treatment for congenital ligamentous aplasia. Further studies using internationally recognized assessments are needed to create a widely accepted treatment algorithm.
Anterior cruciate ligament
Posterior cruciate ligament.
Review and approval from the authors’ institution’s ethics committee were obtained.
The authors declare that there are no conflicts of interest regarding the publication of this paper.